wip forking, added sash source

src/kernel/heap.c

@@ -22,11 +22,6 @@
 
 #define HEAP_ALIGN 4
 
-typedef struct {
-	uint32_t size;
-	void *next;
-} __attribute__ ((packed)) alloc_t;
-
 static alloc_t *free_blocks;
 static void *heap_end;
 

src/kernel/heap.h

@@ -23,6 +23,11 @@
 
 #include <stdint.h>
 
+typedef struct {
+	uint32_t size;
+	void *next;
+} __attribute__ ((packed)) alloc_t;
+
 /**
  * Initializes memory management of the given heap.
  * No overflow stuff is done, so... be careful.

src/kernel/init.c

@@ -56,5 +56,5 @@ void init_idle(void)
 	task_start(user_main, 4096);
 
 	while (1)
-		delay(100);
+		delay(10);
 }

src/kernel/svc.c

@@ -26,6 +26,7 @@
 
 extern void gpio_svc(uint32_t *);
 extern void clock_svc(uint32_t *);
+extern void task_svc(uint32_t *);
 
 void svc_handler(uint32_t *args)
 {
@@ -41,6 +42,11 @@ void svc_handler(uint32_t *args)
 		break;
 	case 2:
 		clock_svc(args);
+		break;
+	case 3:
+		task_svc(args);
+		asm("mov r0, %0" :: "r" (args[0]));
+		break;
 	default:
 		break;
 	}

src/kernel/task.c

@@ -26,6 +26,13 @@
 task_t *current, *prev;
 static uint8_t task_disable = 0;
 
+int task_fork(uint32_t sp);
+void task_svc(uint32_t *args)
+{
+	int result = task_fork(args[0]);
+	args[0] = result;
+}
+
 void task_hold(uint8_t hold)
 {
 	if (hold != 0)
@@ -119,11 +126,12 @@ void task_init(void (*init)(void), uint16_t stackSize)
 
 	// bit 0 - priv, bit 1 - psp/msp
 	asm("\
+		isb; \
+		cpsie i; \
 		mov r0, sp; \
 		msr psp, r0; \
 		mrs r0, control; \
 		orr r0, r0, #3; \
-		cpsie i; \
 		msr control, r0; \
 	");
 
@@ -140,31 +148,41 @@ void task_start(void (*task)(void), uint16_t stackSize)
 	task_hold(0);
 }
 
-/*int fork_ret(void)
+int task_fork_ret(void)
 {
-	return 1;
+	return 0;
 }
 
-int fork(void)
+// Return 0 for child, non-zero for parent
+int task_fork(uint32_t sp)
 {
-	void (*pc)(void) = (void (*)(void))((uint32_t)fork_ret & ~(3));
 	task_hold(1);
 
-	// duplicate task info
-	alloc_t *heapInfo = (alloc_t *)(current->stack - 2);
-	task_t *t = task_create(pc, heapInfo->size);
-	memcpy(t->stack, current->stack, heapInfo->size);
-	uint32_t *sp;
-	asm("mov %0, sp" : "=r" (sp));
-	t->sp = t->stack + (sp - current->stack);
+	// 1. Get a PC for the child
+	void (*pc)(void) = (void (*)(void))((uint32_t)task_fork_ret);
 
-	t->next = current->next;
-	current->next = t;
-	current = t;
+	// 2. Prepare child task
+	alloc_t *stackInfo = (alloc_t *)(((uint8_t *)current->stack)
+		- sizeof(alloc_t));
+	task_t *childTask = task_create(pc, stackInfo->size - 8);
+	for (uint32_t i = 0; i < (stackInfo->size - 8); i++)
+		childTask->stack[i] = current->stack[i];
+
+	//uint32_t *sp;
+	//asm("mov %0, sp" : "=r" (sp));
+	childTask->sp = (uint32_t *)((uint32_t)childTask->stack + (sp
+		- (uint32_t)current->stack));
+
+	// 3. Insert child into task chain
+	childTask->next = current->next;
+	current->next = childTask;
+
+	// 4. Re-enable scheduler, make change happen
 	task_hold(0);
+
 	SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
-	return 0;
-}*/
+	return 1;
+}
 
 __attribute__ ((naked))
 void PendSV_Handler(void) 

src/sash/CHANGES

@@ -0,0 +1,31 @@
+These are the major changes from version 3.7 to version 3.8:
+
+The Makefile has been updated for several distribution's standards.
+The ext2_fs include file location has been changed.
+Some compiler warnings were fixed.
+
+The -ls command has the -n option to print numeric user and group ids.
+
+The -n option might be needed in case the unsuppressable dynamic
+linking used to lookup the names fails.
+
+The -chroot, -pivot_root, and -losetup commands have been added.
+
+The exit status for commands has been implemented (such as -exit).
+Thanks to Tollef Fog Heen for the patches.
+
+
+These are the major changes from version 3.6 to version 3.7:
+
+A few bugs in the dd command have been fixed.
+
+
+These are the major changes from version 3.5 to version 3.6:
+
+The -mount and -umount commands have been modified to work for both
+Linux and BSD systems.  Thanks to Wilbern Cobb for the patches.
+
+The -e and -s options for the -mount command have been added.
+
+The -f option was added to the command line so that script files
+using sash can be executed.

src/sash/Makefile

@@ -0,0 +1,69 @@
+#
+# Makefile for sash
+#
+# The HAVE_GZIP definition adds the -gzip and -gunzip commands.
+# The HAVE_LINUX_ATTR definition adds the -chattr and -lsattr commands.
+# The HAVE_LINUX_CHROOT definition adds the -chroot command.
+# The HAVE_LINUX_PIVOT definition adds the -pivot_root command.
+# The HAVE_LINUX_LOSETUP definition adds the -losetup command.
+# The HAVE_LINUX_MOUNT definition makes -mount and -umount work on Linux.
+# The HAVE_BSD_MOUNT definition makes -mount and -umount work on BSD.
+# The MOUNT_TYPE definition sets the default file system type for -mount.
+#
+# Note that the linker may show warnings about 'statically linked
+# programs' requiring getpwnam, getpwuid, getgrnam and getgrgid.
+# This is unavoidable since those routines use dynamic libraries anyway.
+# Sash will still run, but if there are shared library problems then
+# the user might have to be be careful when using the -chown, -chgrp,
+# and -ls commands.
+#
+
+CC=arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb
+
+#HAVE_GZIP		= 1
+#HAVE_LINUX_ATTR	= 1
+#HAVE_LINUX_CHROOT	= 1
+#HAVE_LINUX_LOSETUP	= 1
+#HAVE_LINUX_PIVOT	= 1
+#HAVE_LINUX_MOUNT	= 1
+#HAVE_BSD_MOUNT		= 0
+MOUNT_TYPE		= '""'
+
+OPT = -O3 -ffreestanding
+
+CFLAGS = $(OPT) -Wall -Wmissing-prototypes \
+	-DMOUNT_TYPE=$(MOUNT_TYPE) #\
+	-DHAVE_GZIP=$(HAVE_GZIP) \
+	-DHAVE_LINUX_ATTR=$(HAVE_LINUX_ATTR) \
+ 	-DHAVE_LINUX_CHROOT=$(HAVE_LINUX_CHROOT) \
+ 	-DHAVE_LINUX_LOSETUP=$(HAVE_LINUX_LOSETUP) \
+ 	-DHAVE_LINUX_PIVOT=$(HAVE_LINUX_PIVOT) \
+	-DHAVE_LINUX_MOUNT=$(HAVE_LINUX_MOUNT) \
+	-DHAVE_BSD_MOUNT=$(HAVE_BSD_MOUNT) \
+
+#LDFLAGS = -static
+#LIBS = -lz
+
+
+DESTDIR =
+BINDIR = /bin
+MANDIR = /usr/man
+
+
+#OBJS = sash.o cmds.o cmd_dd.o cmd_ed.o cmd_grep.o cmd_ls.o cmd_tar.o \
+	cmd_gzip.o cmd_find.o cmd_file.o cmd_chattr.o cmd_ar.o utils.o
+OBJS = sash.o cmds.o cmd_ls.o utils.o
+
+
+sash:	$(OBJS)
+	$(CC) $(LDFLAGS) -o sash $(OBJS) $(LIBS)
+	arm-none-eabi-strip sash
+
+clean:
+	rm -f $(OBJS) sash
+
+install: sash
+	cp sash $(DESTDIR)/$(BINDIR)/sash
+	cp sash.1 $(DESTDIR)/$(MANDIR)/man1/sash.1
+
+$(OBJS):	sash.h

src/sash/README

@@ -0,0 +1,17 @@
+This is release 3.8 of sash, my stand-alone shell for Linux or other systems.
+
+The purpose of this program is to make system recovery possible in
+many cases where there are missing shared libraries or executables.
+It does this by firstly being linked statically, and secondly by
+including versions of many of the standard utilities within itself.
+Read the sash.1 documentation for more details.
+
+Type "make install" to build and install the program and man page.
+
+Several options in the Makefile can be changed to build sash for
+other UNIX-like systems.  In particular, dependencies on Linux file
+systems can be removed and the mount command can be configured.
+
+David I. Bell
+dbell@tip.net.au
+8 March 2014

src/sash/cmd_chattr.c

@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "chattr" and "lsattr" built-in commands.
+ * These commands are optionally built into sash.
+ * They manipulate the important ext2 file system file attribute flags.
+ */
+
+#if	HAVE_LINUX_ATTR
+
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+/*
+ * These were used for old linux versions.
+ * #include <linux/fs.h>
+ * #include <linux/ext2_fs.h>
+ */
+
+#include <ext2fs/ext2_fs.h>
+
+
+#include "sash.h"
+
+
+/*
+ * The chattr command.
+ * This can turn on or off the immutable and append-only ext2 flags.
+ */
+int
+do_chattr(int argc, const char ** argv)
+{
+	const char *	fileName;
+	const char *	options;
+	int *		flagPointer;
+	int		offFlags;
+	int		onFlags;
+	int		oldFlags;
+	int		newFlags;
+	int		fd;
+	int		r;
+
+	r = 0;
+	argc--;
+	argv++;
+
+	/*
+	 * Parse the options.
+	 */
+	onFlags = 0;
+	offFlags = 0;
+
+	while ((**argv == '-') || (**argv == '+'))
+	{
+		options = *argv++;
+		argc--;
+
+		/*
+		 * Point at the proper flags to be modified.
+		 */
+		if (*options++ == '+')
+			flagPointer = &onFlags;
+		else
+			flagPointer = &offFlags;
+
+		/*
+		 * Parse the flag characters.
+		 */
+		while (*options)
+		{
+			switch (*options++)
+			{
+				case 'i':
+					*flagPointer |= EXT2_IMMUTABLE_FL;
+					break;
+
+				case 'a':
+					*flagPointer |= EXT2_APPEND_FL;
+					break;
+
+				default:
+					fprintf(stderr, "Unknown flag '%c'\n",
+						options[-1]);
+
+					return 1;
+			}
+		}
+	}
+
+	/*
+	 * Make sure that the attributes are reasonable.
+	 */
+	if ((onFlags == 0) && (offFlags == 0))
+	{
+		fprintf(stderr, "No attributes specified\n");
+
+		return 1;
+	}
+
+	if ((onFlags & offFlags) != 0)
+	{
+		fprintf(stderr, "Inconsistent attributes specified\n");
+
+		return 1;
+	}
+
+	/*
+	 * Make sure there are some files to affect.
+	 */
+	if (argc <= 0)
+	{
+		fprintf(stderr, "No files specified for setting attributes\n");
+
+		return 1;
+	}
+
+	/*
+	 * Iterate over all of the file names.
+	 */
+	while (argc-- > 0)
+	{
+		fileName = *argv++;
+
+		/*
+		 * Open the file name.
+		 */
+		fd = open(fileName, O_RDONLY | O_NONBLOCK);
+
+		if (fd < 0)
+		{
+			perror(fileName);
+			r = 1;
+			continue;
+		}
+
+		/*
+		 * Read the current ext2 flag bits.
+		 */
+		if (ioctl(fd, EXT2_IOC_GETFLAGS, &oldFlags) < 0)
+		{
+			perror(fileName);
+			r = 1;
+			(void) close(fd);
+
+			continue;
+		}
+
+		/*
+		 * Modify the flag bits as specified.
+		 */
+		newFlags = oldFlags;
+		newFlags |= onFlags;
+		newFlags &= ~offFlags;
+
+		/*
+		 * If the flags aren't being changed, then close this
+		 * file and continue.
+		 */
+		if (newFlags == oldFlags)
+		{
+			(void) close(fd);
+
+			continue;
+		}
+
+		/*
+		 * Set the new ext2 flag bits.
+		 */
+		if (ioctl(fd, EXT2_IOC_SETFLAGS, &newFlags) < 0)
+		{
+			perror(fileName);
+			r = 1;
+			(void) close(fd);
+
+			continue;
+		}
+
+		/*
+		 * Close the file.
+		 */
+		(void) close(fd);
+	}
+
+	return r;
+}
+
+
+/*
+ * The lsattr command.
+ * This lists the immutable and append-only ext2 flags.
+ */
+int
+do_lsattr(int argc, const char ** argv)
+{
+	const char *	fileName;
+	int		r;
+	int		fd;
+	int		status;
+	int		flags;
+	char		string[4];
+
+	r = 0;
+	argc--;
+	argv++;
+
+	/*
+	 * Iterate over all of the file names.
+	 */
+	while (argc-- > 0)
+	{
+		fileName = *argv++;
+
+		/*
+		 * Open the file name.
+		 */
+		fd = open(fileName, O_RDONLY | O_NONBLOCK);
+
+		if (fd < 0)
+		{
+			perror(fileName);
+			r = 1;
+			continue;
+		}
+
+		/*
+		 * Read the ext2 flag bits.
+		 */
+		status = ioctl(fd, EXT2_IOC_GETFLAGS, &flags);
+
+		/*
+		 * Close the file and check the status.
+		 */
+		(void) close(fd);
+
+		if (status < 0)
+		{
+			perror(fileName);
+			r = 1;
+
+			continue;
+		}
+
+		/*
+		 * Build up the string according to the flags.
+		 * This is 'i' for immutable, and 'a' for append only.
+		 */
+		string[0] = ((flags & EXT2_IMMUTABLE_FL) ? 'i' : '-');
+		string[1] = ((flags & EXT2_APPEND_FL) ? 'a' : '-');
+		string[2] = '\0';
+
+		/*
+		 * Print the flags and the file name.
+		 */
+		printf("%s  %s\n", string, fileName);
+	}
+
+	return r;
+}
+
+#endif
+
+
+/* END CODE */

src/sash/cmd_dd.c

@@ -0,0 +1,372 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "dd" built-in command.
+ */
+
+#include "sash.h"
+
+
+#define	PAR_NONE	0
+#define	PAR_IF		1
+#define	PAR_OF		2
+#define	PAR_BS		3
+#define	PAR_COUNT	4
+#define	PAR_SEEK	5
+#define	PAR_SKIP	6
+
+
+typedef	struct
+{
+	const char *	name;
+	int		value;
+} PARAM;
+
+
+static const PARAM	params[] =
+{
+	{"if",		PAR_IF},
+	{"of",		PAR_OF},
+	{"bs",		PAR_BS},
+	{"count",	PAR_COUNT},
+	{"seek",	PAR_SEEK},
+	{"skip",	PAR_SKIP},
+	{NULL,		PAR_NONE}
+};
+
+
+static	long	getNum(const char * cp);
+
+
+int
+do_dd(int argc, const char ** argv)
+{
+	const char *	str;
+	const PARAM *	par;
+	const char *	inFile;
+	const char *	outFile;
+	char *		cp;
+	int		inFd;
+	int		outFd;
+	int		inCc;
+	int		outCc;
+	int		blockSize;
+	long		count;
+	long		seekVal;
+	long		skipVal;
+	long		inFull;
+	long		inPartial;
+	long		outFull;
+	long		outPartial;
+	char *		buf;
+	char		localBuf[BUF_SIZE];
+	int		r;
+
+	inFile = NULL;
+	outFile = NULL;
+	seekVal = 0;
+	skipVal = 0;
+	blockSize = 512;
+	count = -1;
+	r = 0;
+
+	while (--argc > 0)
+	{
+		str = *++argv;
+		cp = strchr(str, '=');
+
+		if (cp == NULL)
+		{
+			fprintf(stderr, "Bad dd argument\n");
+
+			return 1;
+		}
+
+		*cp++ = '\0';
+
+		for (par = params; par->name; par++)
+		{
+			if (strcmp(str, par->name) == 0)
+				break;
+		}
+
+		switch (par->value)
+		{
+			case PAR_IF:
+				if (inFile)
+				{
+					fprintf(stderr, "Multiple input files illegal\n");
+
+					return 1;
+				}
+	
+				inFile = cp;
+				break;
+
+			case PAR_OF:
+				if (outFile)
+				{
+					fprintf(stderr, "Multiple output files illegal\n");
+
+					return 1;
+				}
+
+				outFile = cp;
+				break;
+
+			case PAR_BS:
+				blockSize = getNum(cp);
+
+				if (blockSize <= 0)
+				{
+					fprintf(stderr, "Bad block size value\n");
+
+					return 1;
+				}
+
+				break;
+
+			case PAR_COUNT:
+				count = getNum(cp);
+
+				if (count < 0)
+				{
+					fprintf(stderr, "Bad count value\n");
+
+					return 1;
+				}
+
+				break;
+
+			case PAR_SEEK:
+				seekVal = getNum(cp);
+
+				if (seekVal < 0)
+				{
+					fprintf(stderr, "Bad seek value\n");
+
+					return 1;
+				}
+
+				break;
+
+			case PAR_SKIP:
+				skipVal = getNum(cp);
+
+				if (skipVal < 0)
+				{
+					fprintf(stderr, "Bad skip value\n");
+
+					return 1;
+				}
+
+				break;
+
+			default:
+				fprintf(stderr, "Unknown dd parameter\n");
+
+				return 1;
+		}
+	}
+
+	if (inFile == NULL)
+	{
+		fprintf(stderr, "No input file specified\n");
+
+		return 1;
+	}
+
+	if (outFile == NULL)
+	{
+		fprintf(stderr, "No output file specified\n");
+
+		return 1;
+	}
+
+	buf = localBuf;
+
+	if (blockSize > sizeof(localBuf))
+	{
+		buf = malloc(blockSize);
+
+		if (buf == NULL)
+		{
+			fprintf(stderr, "Cannot allocate buffer\n");
+
+			return 1;
+		}
+	}
+
+	inFull = 0;
+	inPartial = 0;
+	outFull = 0;
+	outPartial = 0;
+
+	inFd = open(inFile, 0);
+
+	if (inFd < 0)
+	{
+		perror(inFile);
+
+		if (buf != localBuf)
+			free(buf);
+
+		return 1;
+	}
+
+	outFd = creat(outFile, 0666);
+
+	if (outFd < 0)
+	{
+		perror(outFile);
+		close(inFd);
+
+		if (buf != localBuf)
+			free(buf);
+
+		return 1;
+	}
+
+	if (skipVal)
+	{
+		if (lseek(inFd, skipVal * blockSize, 0) < 0)
+		{
+			while (skipVal-- > 0)
+			{
+				inCc = read(inFd, buf, blockSize);
+
+				if (inCc < 0)
+				{
+					perror(inFile);
+					r = 1;
+					goto cleanup;
+				}
+
+				if (inCc == 0)
+				{
+					fprintf(stderr, "End of file while skipping\n");
+					r = 1;
+					goto cleanup;
+				}
+			}
+		}
+	}
+
+	if (seekVal)
+	{
+		if (lseek(outFd, seekVal * blockSize, 0) < 0)
+		{
+			perror(outFile);
+			r = 1;
+			goto cleanup;
+		}
+	}
+
+	inCc = 0;
+
+	while (((count < 0) || (inFull + inPartial < count)) &&
+	       (inCc = read(inFd, buf, blockSize)) > 0)
+	{
+		if (inCc < blockSize)
+			inPartial++;
+		else
+			inFull++;
+		cp = buf;
+
+		if (intFlag)
+		{
+			fprintf(stderr, "Interrupted\n");
+			r = 1;
+			goto cleanup;
+		}
+
+		while (inCc > 0)
+		{
+			outCc = write(outFd, cp, inCc);
+
+			if (outCc < 0)
+			{
+				perror(outFile);
+				r = 1;
+				goto cleanup;
+			}
+
+			if (outCc < blockSize)
+				outPartial++;
+			else
+				outFull++;
+			cp += outCc;
+			inCc -= outCc;
+		}
+	}
+
+	if (inCc < 0)
+		perror(inFile);
+
+cleanup:
+	close(inFd);
+
+	if (close(outFd) < 0)
+	{
+		perror(outFile);
+		r = 1;
+	}
+
+	if (buf != localBuf)
+		free(buf);
+
+	printf("%ld+%ld records in\n", inFull, inPartial);
+
+	printf("%ld+%ld records out\n", outFull, outPartial);
+
+	return r;
+}
+
+
+/*
+ * Read a number with a possible multiplier.
+ * Returns -1 if the number format is illegal.
+ */
+static long
+getNum(const char * cp)
+{
+	long	value;
+
+	if (!isDecimal(*cp))
+		return -1;
+
+	value = 0;
+
+	while (isDecimal(*cp))
+		value = value * 10 + *cp++ - '0';
+
+	switch (*cp++)
+	{
+		case 'k':
+			value *= 1024;
+			break;
+
+		case 'b':
+			value *= 512;
+			break;
+
+		case 'w':
+			value *= 2;
+			break;
+
+		case '\0':
+			return value;
+
+		default:
+			return -1;
+	}
+
+	if (*cp)
+		return -1;
+
+	return value;
+}
+
+/* END CODE */

src/sash/cmd_file.c

@@ -0,0 +1,235 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "file" built-in command.
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "sash.h"
+
+
+static const char *	checkFile(const char * name);
+
+
+int
+do_file(int argc, const char ** argv)
+{
+	const char *	name;
+	const char *	info;
+
+	argc--;
+	argv++;
+
+	while (argc-- > 0)
+	{
+		name = *argv++;
+
+		info = checkFile(name);
+
+		if (info == NULL)
+			info = "No information available";
+
+		printf("%s: %s\n", name, info);
+	}
+
+	return 0;
+}
+
+
+/*
+ * Examine the specified file and return a static string which
+ * describes the file type.  Returns NULL on a failure.
+ */
+static const char *
+checkFile(const char * name)
+{
+	int		mode;
+	int		fd;
+	int		cc;
+	int		i;
+	int		ch;
+	int		badCount;
+	char *		cp;
+	struct	stat	statBuf;
+	char		data[8192];
+	static	char	info[1024];
+
+	cp = info;
+	*cp = '\0';
+
+	if (lstat(name, &statBuf) < 0)
+	{
+		if (errno == ENOENT)
+			return "non-existent";
+
+		sprintf(cp, "stat failed: %s", strerror(errno));
+
+		return info;
+	}
+
+	/*
+	 * Check the file type.
+	 */
+	mode = statBuf.st_mode;
+
+	if (S_ISDIR(mode))
+		return "directory";
+
+	if (S_ISCHR(mode))
+		return "character device";
+
+	if (S_ISBLK(mode))
+		return "block device";
+
+	if (S_ISFIFO(mode))
+		return "named pipe";
+
+#ifdef	S_ISLNK
+	if (S_ISLNK(mode))
+		return "symbolic link";
+#endif
+
+#ifdef	S_ISSOCK
+	if (S_ISSOCK(mode))
+		return "socket";
+#endif
+
+	/*
+	 * If the file is not a regular file mention that.
+	 */
+	if (!S_ISREG(mode))
+	{
+		sprintf(cp, "unknown mode 0x%x, \n", mode);
+
+		cp += strlen(cp);
+	}
+
+	/*
+	 * Check for an executable file.
+	 */
+	if ((mode & (S_IEXEC | S_IXGRP | S_IXOTH)) != 0)
+	{
+		strcpy(cp, "executable, ");
+
+		cp += strlen(cp);
+	}
+
+	/*
+	 * The file is a normal file.
+	 * Open it if we can and read in the first block.
+	 */
+	fd = open(name, O_RDONLY);
+
+	if (fd < 0)
+	{
+		sprintf(cp, "unreadable: %s", strerror(errno));
+
+		return info;
+	}
+
+	cc = read(fd, data, sizeof(data));
+
+	if (cc < 0)
+	{
+		sprintf(cp, "read error: %s", strerror(errno));
+
+		(void) close(fd);
+
+		return info;
+	}
+
+	(void) close(fd);
+
+	/*
+	 * Check for an empty file.
+	 */
+	if (cc == 0)
+	{
+		strcpy(cp, "empty file");
+
+		return info;
+	}
+
+	/*
+	 * Check for a script file.
+	 */
+	if ((cc > 2) && (data[0] == '#') && (data[1] == '!'))
+	{
+		char *	begin;
+		char *	end;
+
+		data[sizeof(data) - 1] = '\0';
+
+		begin = &data[2];
+
+		while (*begin == ' ')
+			begin++;
+
+		end = begin;
+
+		while (*end && (*end != ' ') && (*end != '\n'))
+			end++;
+
+		*end = '\0';
+
+		sprintf(cp, "script for \"%s\"", begin);
+
+		return info;
+	}
+
+	/*
+	 * Check for special binary data types.
+	 */
+	if ((data[0] == '\037') && (data[1] == '\235'))
+		return "compressed file";
+
+	if ((data[0] == '\037') && (data[1] == '\213'))
+		return "GZIP file";
+
+	if ((data[0] == '\177') && (memcmp(&data[1], "ELF", 3) == 0))
+	{
+		strcpy(cp, "ELF program");
+
+		return info;
+	}
+
+	/*
+	 * Check for binary data.
+	 */
+	badCount = 0;
+
+	for (i = 0; i < cc; i++)
+	{
+		ch = data[i];
+
+		if ((ch == '\n') || (ch == '\t'))
+			continue;
+
+		if (isspace(ch) || isprint(ch))
+			continue;
+
+		badCount++;
+	}
+
+	if (badCount != 0)
+	{
+		strcpy(cp, "binary");
+
+		return info;
+	}
+
+	/*
+	 * It is just a text file.
+	 */
+	strcpy(cp, "text file");
+
+	return info;
+}
+
+/* END CODE */

src/sash/cmd_find.c

@@ -0,0 +1,376 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "find" built-in command.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <errno.h>
+
+#include "sash.h"
+
+
+#ifdef	S_ISLNK
+#define	LSTAT	lstat
+#else
+#define	LSTAT	stat
+#endif
+
+
+#define	MAX_NAME_SIZE	(1024 * 10)
+
+
+/*
+ * Items that can be specified to restrict the output.
+ */
+static	BOOL		xdevFlag;
+static	dev_t		xdevDevice;
+static	long		fileSize;
+static	const char *	filePattern;
+static	const char *	fileType;
+
+
+/*
+ * Recursive routine to examine the files in a directory.
+ */
+static	void	examineDirectory(const char * path);
+static	BOOL	testFile(const char * fullName, const struct stat * statBuf);
+
+
+
+/*
+ * Find files from the specified directory path.
+ * This is limited to just printing their file names.
+ */
+int
+do_find(int argc, const char ** argv)
+{
+	const char *	cp;
+	const char *	path;
+	struct stat	statBuf;
+
+	argc--;
+	argv++;
+
+	xdevFlag = FALSE;
+	fileType = NULL;
+	filePattern = NULL;
+	fileSize = 0;
+
+	if ((argc <= 0) || (**argv == '-'))
+	{
+		fprintf(stderr, "No path specified\n");
+
+		return 1;
+	}
+
+	path = *argv++;
+	argc--;
+
+	while (argc > 0)
+	{
+		argc--;
+		cp = *argv++;
+
+		if (strcmp(cp, "-xdev") == 0)
+			xdevFlag = TRUE;
+		else if (strcmp(cp, "-type") == 0)
+		{
+			if ((argc <= 0) || (**argv == '-'))
+			{
+				fprintf(stderr, "Missing type string\n");
+
+				return 1;
+			}
+
+			argc--;
+			fileType = *argv++;
+		}
+		else if (strcmp(cp, "-name") == 0)
+		{
+			if ((argc <= 0) || (**argv == '-'))
+			{
+				fprintf(stderr, "Missing file name\n");
+
+				return 1;
+			}
+
+			argc--;
+			filePattern = *argv++;
+		}
+		else if (strcmp(cp, "-size") == 0)
+		{
+			if ((argc <= 0) || (**argv == '-'))
+			{
+				fprintf(stderr, "Missing file size\n");
+
+				return 1;
+			}
+
+			argc--;
+			cp = *argv++;
+
+			fileSize = 0;
+
+			while (isDecimal(*cp))
+				fileSize = fileSize * 10 + (*cp++ - '0');
+
+			if (*cp || (fileSize < 0))
+			{
+				fprintf(stderr, "Bad file size specified\n");
+
+				return 1;
+			}
+		}
+		else
+		{
+			if (*cp != '-')
+				fprintf(stderr, "Missing dash in option\n");
+			else
+				fprintf(stderr, "Unknown option\n");
+
+			return 1;
+		}
+	}
+
+	/*
+	 * Get information about the path and make sure that it
+	 * is a directory.
+	 */
+	if (stat(path, &statBuf) < 0)
+	{
+		fprintf(stderr, "Cannot stat \"%s\": %s\n", path,
+			strerror(errno));
+
+		return 1;
+	}
+
+	if (!S_ISDIR(statBuf.st_mode))
+	{
+		fprintf(stderr, "Path \"%s\" is not a directory\n", path);
+
+		return 1;
+	}
+
+	/*
+	 * Remember the device that this directory is on in case we need it.
+	 */
+	xdevDevice = statBuf.st_dev;
+
+	/*
+	 * If the directory meets the specified criteria, then print it out.
+	 */
+	if (testFile(path, &statBuf))
+		printf("%s\n", path);
+
+	/*
+	 * Now examine the files in the directory.
+	 */
+	examineDirectory(path);
+
+	return 0;
+}
+
+
+/*
+ * Recursive routine to examine the files in a directory.
+ */
+static void
+examineDirectory(const char * path)
+{
+	DIR *		dir;
+	BOOL		needSlash;
+	struct dirent *	entry;
+	struct stat	statBuf;
+	char		fullName[MAX_NAME_SIZE];
+
+	/*
+	 * Open the directory.
+	 */
+	dir = opendir(path);
+
+	if (dir == NULL)
+	{
+		fprintf(stderr, "Cannot read directory \"%s\": %s\n",
+			path, strerror(errno));
+
+		return;
+	}
+
+	/*
+	 * See if a slash is needed.
+	 */
+	needSlash = (*path && (path[strlen(path) - 1] != '/'));
+
+	/*
+	 * Read all of the directory entries and check them,
+	 * except for the current and parent directory entries.
+	 */
+	while (!intFlag && ((entry = readdir(dir)) != NULL))
+	{
+		if ((strcmp(entry->d_name, ".") == 0) ||
+			(strcmp(entry->d_name, "..") == 0))
+		{
+			continue;
+		}
+
+		/*
+		 * Build the full path name.
+		 */
+		strcpy(fullName, path);
+
+		if (needSlash)
+			strcat(fullName, "/");
+
+		strcat(fullName, entry->d_name);
+
+		/*
+		 * Find out about this file.
+		 */
+		if (LSTAT(fullName, &statBuf) < 0)
+		{
+			fprintf(stderr, "Cannot stat \"%s\": %s\n",
+				fullName, strerror(errno));
+
+			continue;
+		}
+
+		/*
+		 * If this file matches the criteria that was
+		 * specified then print its name out.
+		 */
+		if (testFile(fullName, &statBuf))
+			printf("%s\n", fullName);
+
+		/*
+		 * If this is a directory and we are allowed to cross
+		 * mount points or the directory is still on the same
+		 * device, then examine it's files too.
+		 */
+		if (S_ISDIR(statBuf.st_mode) &&
+			(!xdevFlag || (statBuf.st_dev == xdevDevice)))
+		{
+			examineDirectory(fullName);
+		}
+	}
+
+	closedir(dir);
+}
+
+
+/*
+ * Test a file name having the specified status to see if it should
+ * be acted on.  Returns TRUE if the file name has been selected.
+ */
+static BOOL
+testFile(const char * fullName, const struct stat * statBuf)
+{
+	const char *	cp;
+	const char *	entryName;
+	BOOL		wantType;
+	int		mode;
+
+	mode = statBuf->st_mode;
+
+	/*
+	 * Check the file type if it was specified.
+	 */
+	if (fileType != NULL)
+	{
+		wantType = FALSE;
+
+		for (cp = fileType; *cp; cp++)
+		{
+			switch (*cp)
+			{
+				case 'f':
+					if (S_ISREG(mode))
+						wantType = TRUE;
+					break;
+
+				case 'd':
+					if (S_ISDIR(mode))
+						wantType = TRUE;
+
+					break;
+
+				case 'p':
+					if (S_ISFIFO(mode))
+						wantType = TRUE;
+
+					break;
+
+				case 'c':
+					if (S_ISCHR(mode))
+						wantType = TRUE;
+
+					break;
+
+				case 'b':
+					if (S_ISBLK(mode))
+						wantType = TRUE;
+
+					break;
+
+				case 's':
+					if (S_ISSOCK(mode))
+						wantType = TRUE;
+
+					break;
+
+#ifdef	S_ISLNK
+				case 'l':
+					if (S_ISLNK(mode))
+						wantType = TRUE;
+
+					break;
+#endif
+				default:
+					break;
+			}
+		}
+
+		if (!wantType)
+			return FALSE;
+	}
+
+	/*
+	 * Check the file size if it was specified.
+	 * This check only lets regular files and directories through.
+	 */
+	if (fileSize > 0)
+	{
+		if (!S_ISREG(mode) && !S_ISDIR(mode))
+			return FALSE;
+
+		if (statBuf->st_size < fileSize)
+			return FALSE;
+	}
+
+	/*
+	 * Check the file name pattern if it was specified.
+	 */
+	if (filePattern != NULL)
+	{
+		entryName = strrchr(fullName, '/');
+
+		if (entryName)
+			entryName++;
+		else
+			entryName = fullName;
+
+		if (!match(entryName, filePattern))
+			return FALSE;
+	}
+
+	/*
+	 * This file name is wanted.
+	 */
+	return TRUE;
+}
+
+/* END CODE */

src/sash/cmd_grep.c

@@ -0,0 +1,197 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "grep" built-in command.
+ */
+
+#include <ctype.h>
+
+#include "sash.h"
+
+
+static	BOOL	search
+	(const char * string, const char * word, BOOL ignoreCase);
+
+
+int
+do_grep(int argc, const char ** argv)
+{
+	FILE *		fp;
+	const char *	word;
+	const char *	name;
+	const char *	cp;
+	BOOL		tellName;
+	BOOL		ignoreCase;
+	BOOL		tellLine;
+	long		line;
+	char		buf[BUF_SIZE];
+	int		r;
+
+	r = 1;
+	ignoreCase = FALSE;
+	tellLine = FALSE;
+
+	argc--;
+	argv++;
+
+	if (**argv == '-')
+	{
+		argc--;
+		cp = *argv++;
+
+		while (*++cp) switch (*cp)
+		{
+			case 'i':
+				ignoreCase = TRUE;
+				break;
+
+			case 'n':
+				tellLine = TRUE;
+				break;
+
+			default:
+				fprintf(stderr, "Unknown option\n");
+
+				return 1;
+		}
+	}
+
+	word = *argv++;
+	argc--;
+
+	tellName = (argc > 1);
+
+	while (argc-- > 0)
+	{
+		name = *argv++;
+
+		fp = fopen(name, "r");
+
+		if (fp == NULL)
+		{
+			perror(name);
+			r = 1;
+
+			continue;
+		}
+
+		line = 0;
+
+		while (fgets(buf, sizeof(buf), fp))
+		{
+			if (intFlag)
+			{
+				fclose(fp);
+
+				return 1;
+			}
+
+			line++;
+
+			cp = &buf[strlen(buf) - 1];
+
+			if (*cp != '\n')
+				fprintf(stderr, "%s: Line too long\n", name);
+
+			if (search(buf, word, ignoreCase))
+			{
+				r = 0;
+				if (tellName)
+					printf("%s: ", name);
+
+				if (tellLine)
+					printf("%ld: ", line);
+
+				fputs(buf, stdout);
+			}
+		}
+
+		if (ferror(fp))
+			perror(name);
+
+		fclose(fp);
+	}
+
+	return r;
+}
+
+
+/*
+ * See if the specified word is found in the specified string.
+ */
+static BOOL
+search(const char * string, const char * word, BOOL ignoreCase)
+{
+	const char *	cp1;
+	const char *	cp2;
+	int		len;
+	int		lowFirst;
+	int		ch1;
+	int		ch2;
+
+	len = strlen(word);
+
+	if (!ignoreCase)
+	{
+		while (TRUE)
+		{
+			string = strchr(string, word[0]);
+
+			if (string == NULL)
+				return FALSE;
+
+			if (memcmp(string, word, len) == 0)
+				return TRUE;
+
+			string++;
+		}
+	}
+
+	/*
+	 * Here if we need to check case independence.
+	 * Do the search by lower casing both strings.
+	 */
+	lowFirst = *word;
+
+	if (isupper(lowFirst))
+		lowFirst = tolower(lowFirst);
+
+	while (TRUE)
+	{
+		while (*string && (*string != lowFirst) &&
+			(!isupper(*string) || (tolower(*string) != lowFirst)))
+		{
+			string++;
+		}
+
+		if (*string == '\0')
+			return FALSE;
+
+		cp1 = string;
+		cp2 = word;
+
+		do
+		{
+			if (*cp2 == '\0')
+				return TRUE;
+
+			ch1 = *cp1++;
+
+			if (isupper(ch1))
+				ch1 = tolower(ch1);
+
+			ch2 = *cp2++;
+
+			if (isupper(ch2))
+				ch2 = tolower(ch2);
+
+		}
+		while (ch1 == ch2);
+
+		string++;
+	}
+}
+
+/* END CODE */

src/sash/cmd_gzip.c

@@ -0,0 +1,698 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "gzip" and "gunzip" built-in commands.
+ * These commands are optionally built into sash.
+ * This uses the zlib library by Jean-loup Gailly to compress and
+ * uncompress the files.
+ */
+
+#if	HAVE_GZIP
+
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <zlib.h>
+
+#include "sash.h"
+
+
+#define	GZ_EXT		".gz"
+#define	TGZ_EXT		".tgz"
+#define	Z_EXT		".Z"
+#define	TAR_EXT		".tar"
+#define	NO_EXT		""
+
+
+/*
+ * Tables of conversions to make to file extensions.
+ */
+typedef	struct
+{
+	const char *	input;
+	const char *	output;
+} CONVERT;
+
+
+static const CONVERT	gzipConvertTable[] =
+{
+	{TAR_EXT,	TGZ_EXT},
+	{NO_EXT,	GZ_EXT}
+};
+
+
+static const CONVERT	gunzipConvertTable[] =
+{
+	{TGZ_EXT,	TAR_EXT},
+	{GZ_EXT,	NO_EXT},
+	{Z_EXT,		NO_EXT},
+	{NO_EXT,	NO_EXT}
+};
+
+
+/*
+ * Local routines to compress and uncompress files.
+ */
+static BOOL	gzip(const char * inputFile, const char * outputFile);
+static BOOL	gunzip(const char * inputFile, const char * outputFile);
+
+static const char * convertName
+	(const CONVERT * table, const char * inFile);
+
+
+int
+do_gzip(int argc, const char ** argv)
+{
+	const char *	outPath;
+	const char *	inFile;
+	const char *	outFile;
+	int		i;
+	int		r;
+
+	r = 0;
+	argc--;
+	argv++;
+
+	/*
+	 * Look for the -o option if it is present.
+	 * If present, it must be at the end of the command.
+	 * Remember the output path and remove it if found.
+	 */
+	outPath = NULL;
+
+	if ((argc >= 2) && (strcmp(argv[argc - 2], "-o") == 0) &&
+		(argv[argc - 1][0] != '-'))
+	{
+		argc -= 2;
+		outPath = argv[argc + 1];
+	}
+
+	/*
+	 * Now make sure that there are no more options.
+	 */
+	for (i = 0; i < argc; i++)
+	{
+		if (argv[i][0] == '-')
+		{
+			if (strcmp(argv[i], "-o") == 0)
+				fprintf(stderr, "Illegal use of -o\n");
+			else
+				fprintf(stderr, "Illegal option\n");
+
+			return 1;
+		}
+	}
+	
+	/*
+	 * If there is no output path specified, then compress each of
+	 * the input files in place using their full paths.  The input
+	 * file names are then deleted.
+	 */
+	if (outPath == NULL)
+	{
+		while (!intFlag && (argc-- > 0))
+		{
+			inFile = *argv++;
+
+			outFile = convertName(gzipConvertTable, inFile);
+
+			/*
+			 * Try to compress the file.
+			 */
+			if (!gzip(inFile, outFile))
+			{
+				r = 1;
+
+				continue;
+			}
+
+			/*
+			 * This was successful.
+			 * Try to delete the original file now.
+			 */
+			if (unlink(inFile) < 0)
+			{
+				fprintf(stderr, "%s: %s\n", inFile,
+					"Compressed ok but unlink failed");
+
+				r = 1;
+			}
+		}
+
+		return r;
+	}
+
+	/*
+	 * There is an output path specified.
+	 * If it is not a directory, then either compress the single
+	 * specified input file to the exactly specified output path,
+	 * or else complain.
+	 */
+	if (!isDirectory(outPath))
+	{
+		if (argc == 1)
+			r = !gzip(*argv, outPath);
+		else
+		{
+			fprintf(stderr, "Exactly one input file is required\n");
+			r = 1;
+		}
+
+		return r;
+	}
+
+	/*
+	 * There was an output directory specified.
+	 * Compress each of the input files into the specified
+	 * output directory, converting their extensions if possible.
+	 */
+	while (!intFlag && (argc-- > 0))
+	{
+		inFile = *argv++;
+
+		/*
+		 * Strip the path off of the input file name to make
+		 * the beginnings of the output file name.
+		 */
+		outFile = strrchr(inFile, '/');
+
+		if (outFile)
+			outFile++;
+		else
+			outFile = inFile;
+
+		/*
+		 * Convert the extension of the output file name if possible.
+		 * If we can't, then that is ok.
+		 */
+		outFile = convertName(gzipConvertTable, outFile);
+
+		/*
+		 * Now build the output path name by prefixing it with
+		 * the output directory.
+		 */
+		outFile = buildName(outPath, outFile);
+
+		/*
+		 * Compress the input file without deleting the input file.
+		 */
+		if (!gzip(inFile, outFile))
+			r = 1;
+	}
+
+	return r;
+}
+
+
+int
+do_gunzip(int argc, const char ** argv)
+{
+	const char *	outPath;
+	const char *	inFile;
+	const char *	outFile;
+	int		i;
+	int		r;
+
+	r = 0;
+	argc--;
+	argv++;
+
+	/*
+	 * Look for the -o option if it is present.
+	 * If present, it must be at the end of the command.
+	 * Remember the output path and remove it if found.
+	 */
+	outPath = NULL;
+
+	if ((argc >= 2) && (strcmp(argv[argc - 2], "-o") == 0) &&
+		(argv[argc - 1][0] != '-'))
+	{
+		argc -= 2;
+		outPath = argv[argc + 1];
+	}
+
+	/*
+	 * Now make sure that there are no more options.
+	 */
+	for (i = 0; i < argc; i++)
+	{
+		if (argv[i][0] == '-')
+		{
+			if (strcmp(argv[i], "-o") == 0)
+				fprintf(stderr, "Illegal use of -o\n");
+			else
+				fprintf(stderr, "Illegal option\n");
+
+			return 1;
+		}
+	}
+	
+	/*
+	 * If there is no output path specified, then uncompress each of
+	 * the input files in place using their full paths.  They must
+	 * have one of the proper compression extensions which is converted.
+	 * The input file names are then deleted.
+	 */
+	if (outPath == NULL)
+	{
+		while (!intFlag && (argc-- > 0))
+		{
+			inFile = *argv++;
+
+			outFile = convertName(gunzipConvertTable, inFile);
+
+			if (inFile == outFile)
+			{
+				fprintf(stderr, "%s: %s\n", inFile,
+					"missing compression extension");
+				r = 1;
+
+				continue;
+			}
+
+			/*
+			 * Try to uncompress the file.
+			 */
+			if (!gunzip(inFile, outFile))
+			{
+				r = 1;
+				continue;
+			}
+
+			/*
+			 * This was successful.
+			 * Try to delete the original file now.
+			 */
+			if (unlink(inFile) < 0)
+			{
+				fprintf(stderr, "%s: %s\n", inFile,
+					"Uncompressed ok but unlink failed");
+				r = 1;
+			}
+		}
+
+		return r;
+	}
+
+	/*
+	 * There is an output path specified.
+	 * If the output path is a device file then uncompress each of
+	 * the input files to the device file.
+	 */
+	if (isDevice(outPath))
+	{
+		while (!intFlag && (argc-- > 0))
+		{
+			if (!gunzip(*argv++, outPath))
+				r = 1;
+		}
+
+		return r;
+	}
+
+	/*
+	 * If the output path is not a directory then either uncompress the
+	 * single specified input file to the exactly specified output path,
+	 * or else complain.
+	 */
+	if (!isDirectory(outPath))
+	{
+		if (argc == 1)
+			return !gunzip(*argv, outPath);
+		else
+			fprintf(stderr, "Exactly one input file is required\n");
+
+		return 1;
+	}
+
+	/*
+	 * There was an output directory specified.
+	 * Uncompress each of the input files into the specified
+	 * output directory, converting their extensions if possible.
+	 */
+	while (!intFlag && (argc-- > 0))
+	{
+		inFile = *argv++;
+
+		/*
+		 * Strip the path off of the input file name to make
+		 * the beginnings of the output file name.
+		 */
+		outFile = strrchr(inFile, '/');
+
+		if (outFile)
+			outFile++;
+		else
+			outFile = inFile;
+
+		/*
+		 * Convert the extension of the output file name if possible.
+		 * If we can't, then that is ok.
+		 */
+		outFile = convertName(gunzipConvertTable, outFile);
+
+		/*
+		 * Now build the output path name by prefixing it with
+		 * the output directory.
+		 */
+		outFile = buildName(outPath, outFile);
+
+		/*
+		 * Uncompress the input file without deleting the input file.
+		 */
+		if (!gunzip(inFile, outFile))
+			r = 1;
+	}
+
+	return r;
+}
+
+
+/*
+ * Compress the specified input file to produce the output file.
+ * Returns TRUE if successful.
+ */
+static BOOL
+gzip(const char * inputFileName, const char * outputFileName)
+{
+	gzFile		outGZ;
+	int		inFD;
+	int		len;
+	int		err;
+	struct	stat	statBuf1;
+	struct	stat	statBuf2;
+	char		buf[BUF_SIZE];
+
+	outGZ = NULL;
+	inFD = -1;
+
+	/*
+	 * See if the output file is the same as the input file.
+	 * If so, complain about it.
+	 */
+	if (stat(inputFileName, &statBuf1) < 0)
+	{
+		perror(inputFileName);
+
+		return FALSE;
+	}
+
+	if (stat(outputFileName, &statBuf2) < 0)
+	{
+		statBuf2.st_ino = -1;
+		statBuf2.st_dev = -1;
+	}
+
+	if ((statBuf1.st_dev == statBuf2.st_dev) &&
+		(statBuf1.st_ino == statBuf2.st_ino))
+	{
+		fprintf(stderr,
+			"Cannot compress file \"%s\" on top of itself\n",
+			inputFileName);
+
+		return FALSE;
+	}
+
+	/*
+	 * Open the input file.
+	 */
+	inFD = open(inputFileName, O_RDONLY);
+
+	if (inFD < 0)
+	{
+		perror(inputFileName);
+
+		goto failed;
+	}
+
+	/*
+	 * Ask the zlib library to open the output file.
+	 */
+	outGZ = gzopen(outputFileName, "wb9");
+
+	if (outGZ == NULL)
+	{
+		fprintf(stderr, "%s: gzopen failed\n", outputFileName);
+
+		goto failed;
+	}
+
+	/*
+	 * Read the uncompressed data from the input file and write
+	 * the compressed data to the output file.
+	 */
+	while ((len = read(inFD, buf, sizeof(buf))) > 0)
+	{
+		if (gzwrite(outGZ, buf, len) != len)
+		{
+			fprintf(stderr, "%s: %s\n", inputFileName,
+				gzerror(outGZ, &err));
+
+			goto failed;
+		}
+
+		if (intFlag)
+			goto failed;
+	}
+
+	if (len < 0)
+	{
+		perror(inputFileName);
+
+		goto failed;
+	}
+
+	/*
+	 * All done, close the files.
+	 */
+	if (close(inFD))
+	{
+		perror(inputFileName);
+
+		goto failed;
+	}
+
+	inFD = -1;
+
+	if (gzclose(outGZ) != Z_OK)
+	{
+		fprintf(stderr, "%s: gzclose failed\n", outputFileName);
+
+		goto failed;
+	}
+
+	outGZ = NULL;
+
+	/*
+	 * Success.
+	 */
+	return TRUE;
+
+
+/*
+ * Here on an error, to clean up.
+ */
+failed:
+	if (inFD >= 0)
+		(void) close(inFD);
+
+	if (outGZ != NULL)
+		(void) gzclose(outGZ);
+
+	return FALSE;
+}
+
+
+/*
+ * Uncompress the input file to produce the output file.
+ * Returns TRUE if successful.
+ */
+static BOOL
+gunzip(const char * inputFileName, const char * outputFileName)
+{
+	gzFile		inGZ;
+	int		outFD;
+	int		len;
+	int		err;
+	struct	stat	statBuf1;
+	struct	stat	statBuf2;
+	char		buf[BUF_SIZE];
+
+	inGZ = NULL;
+	outFD = -1;
+
+	/*
+	 * See if the output file is the same as the input file.
+	 * If so, complain about it.
+	 */
+	if (stat(inputFileName, &statBuf1) < 0)
+	{
+		perror(inputFileName);
+
+		return FALSE;
+	}
+
+	if (stat(outputFileName, &statBuf2) < 0)
+	{
+		statBuf2.st_ino = -1;
+		statBuf2.st_dev = -1;
+	}
+
+	if ((statBuf1.st_dev == statBuf2.st_dev) &&
+		(statBuf1.st_ino == statBuf2.st_ino))
+	{
+		fprintf(stderr,
+			"Cannot uncompress file \"%s\" on top of itself\n",
+			inputFileName);
+
+		return FALSE;
+	}
+
+	/*
+	 * Ask the zlib library to open the input file.
+	 */
+	inGZ = gzopen(inputFileName, "rb");
+
+	if (inGZ == NULL)
+	{
+		fprintf(stderr, "%s: gzopen failed\n", inputFileName);
+
+		return FALSE;
+	}
+
+	/*
+	 * Create the output file.
+	 */
+	if (isDevice(outputFileName))
+		outFD = open(outputFileName, O_WRONLY);
+	else
+		outFD = open(outputFileName, O_WRONLY|O_CREAT|O_TRUNC, 0666);
+
+	if (outFD < 0)
+	{
+		perror(outputFileName);
+
+		goto failed;
+	}
+
+	/*
+	 * Read the compressed data from the input file and write
+	 * the uncompressed data extracted from it to the output file.
+	 */
+	while ((len = gzread(inGZ, buf, sizeof(buf))) > 0)
+	{
+		if (fullWrite(outFD, buf, len) < 0)
+		{
+			perror(outputFileName);
+
+			goto failed;
+		}
+
+		if (intFlag)
+			goto failed;
+	}
+
+	if (len < 0)
+	{
+		fprintf(stderr, "%s: %s\n", inputFileName,
+			gzerror(inGZ, &err));
+
+		goto failed;
+	}
+
+	/*
+	 * All done, close the files.
+	 */
+	if (close(outFD))
+	{
+		perror(outputFileName);
+
+		goto failed;
+	}
+
+	outFD = -1;
+
+	if (gzclose(inGZ) != Z_OK)
+	{
+		fprintf(stderr, "%s: gzclose failed\n", inputFileName);
+
+		goto failed;
+	}
+
+	inGZ = NULL;
+
+	/*
+	 * Success.
+	 */
+	return TRUE;
+
+
+/*
+ * Here on an error, to clean up.
+ */
+failed:
+	if (outFD >= 0)
+		(void) close(outFD);
+
+	if (inGZ != NULL)
+		(void) gzclose(inGZ);
+
+	return FALSE;
+}
+
+
+/*
+ * Convert an input file name to an output file name according to
+ * the specified convertion table.  The returned name points into a
+ * static buffer which is overwritten on each call.  The table must
+ * end in an entry which always specifies a successful conversion.
+ * If no conversion is done the original input file name pointer is
+ * returned.
+ */
+const char *
+convertName(const CONVERT * table, const char * inputFile)
+{
+	int		inputLength;
+	int		testLength;
+	static char	buf[PATH_LEN];
+
+	inputLength = strlen(inputFile);
+
+	for (;;)
+	{
+		testLength = strlen(table->input);
+
+		if ((inputLength >= testLength) &&
+			(memcmp(table->input,
+				inputFile + inputLength - testLength,
+				testLength) == 0))
+		{
+			break;
+		}
+
+		table++;
+	}
+
+	/*
+	 * If no conversion was done, return the original pointer.
+	 */
+	if ((testLength == 0) && (table->output[0] == '\0'))
+		return inputFile;
+
+	/*
+	 * Build the new name and return it.
+	 */
+	memcpy(buf, inputFile, inputLength - testLength);
+
+	memcpy(buf + inputLength - testLength, table->output,
+		strlen(table->output) + 1);
+
+	return buf;
+}
+
+
+#endif
+
+/* END CODE */

src/sash/cmd_ls.c

@@ -0,0 +1,597 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * The "ls" built-in command.
+ */
+
+#include "sash.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "dirent.h"
+#include <pwd.h>
+#include <grp.h>
+
+
+#define	LISTSIZE	8192
+
+
+#ifdef	S_ISLNK
+#define	LSTAT	lstat
+#else
+#define	LSTAT	stat
+#endif
+
+
+/*
+ * Flags for the LS command.
+ */
+#define	LSF_LONG	0x01
+#define	LSF_DIR		0x02
+#define	LSF_INODE	0x04
+#define	LSF_MULT	0x08
+#define	LSF_FLAG	0x10
+#define	LSF_COLUMN	0x20
+#define	LSF_NUMERIC	0x40
+
+
+/*
+ * Data holding list of files.
+ */
+static	char **	list;
+static	int	listSize;
+static	int	listUsed;
+
+/*
+ * Cached user and group name data.
+ */
+static	char	userName[12];
+static	int	userId;
+static	BOOL	userIdKnown;
+static	char	groupName[12];
+static	int	groupId;
+static	BOOL	groupIdKnown;
+
+
+/*
+ * Local procedures.
+ */
+static	void	listFile(
+	const char *		name,
+	const struct stat *	statBuf,
+	int			flags,
+	int			width
+);
+
+static	BOOL	addListName(const char * fileName);
+static	void	listAllFiles(int flags, int displayWidth);
+static	void	clearListNames(void);
+
+
+int
+do_ls(int argc, const char ** argv)
+{
+	const char *	cp;
+	const char *	name;
+	int		flags;
+	int		i;
+	int		displayWidth;
+	BOOL		endSlash;
+	DIR *		dirp;
+	struct dirent *	dp;
+	char		fullName[PATH_LEN];
+	struct	stat	statBuf;
+	int		r;
+
+	static const char *	def[] = {"."};
+
+	/*
+	 * Reset for a new listing run.
+	 */
+	clearListNames();
+
+	userIdKnown = FALSE;
+	groupIdKnown = FALSE;
+
+	displayWidth = 0;
+	flags = 0;
+
+	/*
+	 * Handle options.
+	 */
+	argc--;
+	argv++;
+
+	while ((argc > 0) && (**argv == '-'))
+	{
+		cp = *argv++ + 1;
+		argc--;
+
+		while (*cp) switch (*cp++)
+		{
+			case 'l':	flags |= LSF_LONG; break;
+			case 'n':	flags |= LSF_NUMERIC; break;
+			case 'd':	flags |= LSF_DIR; break;
+			case 'i':	flags |= LSF_INODE; break;
+			case 'F':	flags |= LSF_FLAG; break;
+			case 'C':	flags |= LSF_COLUMN; break;
+
+			default:
+				fprintf(stderr, "Unknown option -%c\n", cp[-1]);
+
+				return 1;
+		}
+	}
+
+	/*
+	 * If long or numeric listing is specified then turn off column listing.
+	 */
+	if (flags & (LSF_LONG | LSF_NUMERIC))
+		flags &= ~LSF_COLUMN;
+
+	/*
+	 * If column listing is specified then calculate the maximum
+	 * width available for the columns of file names.
+	 * This is settable using the COLS environment variable.
+	 */
+	if (flags & LSF_COLUMN)
+	{
+		name = getenv("COLS");
+
+		if (name)
+			displayWidth = atoi(name);
+
+		if (displayWidth <= 0)
+			displayWidth = 80;
+	}
+
+	/*
+	 * If no arguments are given set up to show the current directory.
+	 */
+	if (argc <= 0)
+	{
+		argc = 1;
+		argv = def;
+	}
+
+	if (argc > 1)
+		flags |= LSF_MULT;
+
+	/*
+	 * Make one pass over the file names to collect together
+	 * all of the files which are not directories.
+	 * We will process them all as one list.
+	 */
+	for (i = 0; i < argc; i++)
+	{
+		if ((flags & LSF_DIR) || !isDirectory(argv[i]))
+		{
+			if (!addListName(argv[i]))
+				return 1;
+		}
+	}
+
+	/*
+	 * List those file names, and then clear the list.
+	 */
+	listAllFiles(flags, displayWidth);
+	clearListNames();
+
+	/*
+	 * If directories were being listed as themselves, then we are done.
+	 */
+	if (flags & LSF_DIR)
+		return r;
+
+	/*
+	 * Now iterate over the file names processing the directories.
+	 */
+	while (!intFlag && (argc-- > 0))
+	{
+		name = *argv++;
+		endSlash = (*name && (name[strlen(name) - 1] == '/'));
+
+		if (LSTAT(name, &statBuf) < 0)
+		{
+			perror(name);
+			r = 1;
+
+			continue;
+		}
+
+		/*
+		 * If this file name is not a directory, then ignore it.
+		 */
+		if (!S_ISDIR(statBuf.st_mode))
+			continue;
+
+		/*
+		 * Collect all the files in the directory.
+		 */
+		dirp = opendir(name);
+
+		if (dirp == NULL)
+		{
+			perror(name);
+
+			continue;
+		}
+
+		if (flags & LSF_MULT)
+			printf("\n%s:\n", name);
+
+		while (!intFlag && ((dp = readdir(dirp)) != NULL))
+		{
+			fullName[0] = '\0';
+
+			if ((*name != '.') || (name[1] != '\0'))
+			{
+				strcpy(fullName, name);
+
+				if (!endSlash)
+					strcat(fullName, "/");
+			}
+
+			strcat(fullName, dp->d_name);
+
+			/*
+			 * Save the file name in the list.
+			 */
+			if (!addListName(fullName))
+			{
+				closedir(dirp);
+
+				return 1;
+			}
+		}
+
+		closedir(dirp);
+
+		/*
+		 * List the files we collected in this directory,
+		 * and then clear the list.
+		 */
+		listAllFiles(flags, displayWidth);
+		clearListNames();
+	}
+
+	return r;
+}
+
+
+/*
+ * List all of the files in the current list of files.
+ * The files are displayed according to the specified flags,
+ * in the specified display width.
+ */
+static void
+listAllFiles(int flags, int displayWidth)
+{
+	const char *	name;
+	const char *	cp;
+	int		fileWidth;
+	int		column;
+	int		len;
+	int		i;
+	struct stat	statBuf;
+
+	/*
+	 * Initialise width data until we need it.
+	 */
+	fileWidth = 0;
+	column = 0;
+
+	/*
+	 * Sort the files in the list.
+	 */
+	qsort((void *) list, listUsed, sizeof(char *), nameSort);
+
+	/*
+	 * If we are showing the files in columns then calculate the
+	 * maximum width of all of the file names, taking into account
+	 * various factors.
+	 */
+	if (flags & LSF_COLUMN)
+	{
+		for (i = 0; i < listUsed; i++)
+		{
+			len = strlen(list[i]);
+
+			if (fileWidth < len)
+				fileWidth = len;
+		}
+
+		if (flags & LSF_FLAG)
+			fileWidth++;
+
+		if (flags & LSF_INODE)
+			fileWidth += 8;
+
+		fileWidth += 2;
+	}
+
+	/*
+	 * Now list the fileNames.
+	 */
+	for (i = 0; i < listUsed; i++)
+	{
+		name = list[i];
+
+		if (LSTAT(name, &statBuf) < 0)
+		{
+			perror(name);
+
+			continue;
+		}
+
+		cp = strrchr(name, '/');
+
+		if (cp)
+			cp++;
+		else
+			cp = name;
+
+		/*
+		 * List the file in the next column or at the end
+		 * of a line depending on the width left.
+		 */
+		if (column + fileWidth * 2 >= displayWidth)
+		{
+			listFile(cp, &statBuf, flags, 0);
+			column = 0;
+		}
+		else
+		{
+			listFile(cp, &statBuf, flags, fileWidth);
+			column += fileWidth;
+		}
+	}
+
+	/*
+	 * Terminate the last file name if necessary.
+	 */
+	if (column > 0)
+		fputc('\n', stdout);
+}
+
+
+/*
+ * Do a listing of a particular file name according to the flags.
+ * The output is shown within the specified width if it is nonzero,
+ * or on its own line if the width is zero.
+ */
+static void
+listFile(
+	const char *		name,
+	const struct stat *	statBuf,
+	int			flags,
+	int			width
+)
+{
+	char *		cp;
+	struct passwd *	pwd;
+	struct group *	grp;
+	int		len;
+	int		mode;
+	int		flagChar;
+	int		usedWidth;
+	char		buf[PATH_LEN];
+
+	mode = statBuf->st_mode;
+
+	/*
+	 * Initialise buffers for use.
+	 */
+	cp = buf;
+	buf[0] = '\0';
+	flagChar = '\0';
+
+	/*
+	 * Show the inode number if requested.
+	 */
+	if (flags & LSF_INODE)
+	{
+		sprintf(cp, "%7ld ", statBuf->st_ino);
+		cp += strlen(cp);
+	}
+
+	/*
+	 * Create the long or numeric status line if requested.
+	 */
+	if (flags & (LSF_LONG | LSF_NUMERIC))
+	{
+		strcpy(cp, modeString(mode));
+		cp += strlen(cp);
+
+		sprintf(cp, "%3ld ", (long) statBuf->st_nlink);
+		cp += strlen(cp);
+
+		if (!userIdKnown || (statBuf->st_uid != userId))
+		{
+			if (flags & LSF_NUMERIC)
+				pwd = 0;
+			else
+				pwd = getpwuid(statBuf->st_uid);
+
+			if (pwd)
+				strcpy(userName, pwd->pw_name);
+			else
+				sprintf(userName, "%d", statBuf->st_uid);
+
+			userId = statBuf->st_uid;
+			userIdKnown = TRUE;
+		}
+
+		sprintf(cp, "%-8s ", userName);
+		cp += strlen(cp);
+
+		if (!groupIdKnown || (statBuf->st_gid != groupId))
+		{
+			if (flags & LSF_NUMERIC)
+				grp = 0;
+			else
+				grp = getgrgid(statBuf->st_gid);
+
+			if (grp)
+				strcpy(groupName, grp->gr_name);
+			else
+				sprintf(groupName, "%d", statBuf->st_gid);
+
+			groupId = statBuf->st_gid;
+			groupIdKnown = TRUE;
+		}
+
+		sprintf(cp, "%-8s ", groupName);
+		cp += strlen(cp);
+
+		if (S_ISBLK(mode) || S_ISCHR(mode))
+		{
+			sprintf(cp, "%3lu, %3lu ",
+				((unsigned long) statBuf->st_rdev) >> 8,
+				((unsigned long) statBuf->st_rdev) & 0xff);
+		}
+		else
+			sprintf(cp, "%8ld ", statBuf->st_size);
+
+		cp += strlen(cp);
+
+		sprintf(cp, " %-12s ", timeString(statBuf->st_mtime));
+	}
+
+	/*
+	 * Set the special character if the file is a directory or
+	 * symbolic link or executable and the display was requested.
+	 */
+	if (flags & LSF_FLAG)
+	{
+		if (S_ISDIR(mode))
+			flagChar = '/';
+#ifdef S_ISLNK
+		else if (S_ISLNK(mode))
+			flagChar = '@';
+#endif
+		else if ((mode & 0111) != 0)
+			flagChar = '*';
+	}
+
+	/*
+	 * Print the status info followed by the file name.
+	 */
+	fputs(buf, stdout);
+	fputs(name, stdout);
+
+	if (flagChar)
+		fputc(flagChar, stdout);
+
+	/*
+	 * Calculate the width used so far.
+	 */
+	usedWidth = strlen(buf) + strlen(name);
+
+	if (flagChar)
+		usedWidth++;
+
+	/*
+	 * Show where a symbolic link points.
+	 */
+#ifdef	S_ISLNK
+	if ((flags & LSF_LONG) && S_ISLNK(mode))
+	{
+		len = readlink(name, buf, PATH_LEN - 1);
+
+		if (len >= 0)
+		{
+			buf[len] = '\0';
+			printf(" -> %s", buf);
+		}
+
+		usedWidth += strlen(buf) + 4;
+	}
+#endif
+
+	/*
+	 * If no width was given then just end the line with a newline.
+	 */
+	if (width == 0)
+	{
+		fputc('\n', stdout);
+
+		return;
+	}
+
+	/*
+	 * There is a width given.
+	 * Print as many spaces as it takes to reach that width.
+	 */
+	while (usedWidth++ < width)
+		fputc(' ', stdout);
+}
+
+
+/*
+ * Save a file name to the end of the static list, reallocating if necessary.
+ * The file name is copied into allocated memory owned by the list.
+ * Returns TRUE on success.
+ */
+static BOOL
+addListName(const char * fileName)
+{
+	char **	newList;
+
+	/*
+	 * Reallocate the list if necessary.
+	 */
+	if (listUsed >= listSize)
+	{
+		newList = realloc(list,
+			((sizeof(char **)) * (listSize + LISTSIZE)));
+
+		if (newList == NULL)
+		{
+			fprintf(stderr, "No memory for file name buffer\n");
+
+			return FALSE;
+		}
+
+		list = newList;
+		listSize += LISTSIZE;
+	}
+
+	/*
+	 * Copy the file name into the next entry.
+	 */
+	list[listUsed] = strdup(fileName);
+
+	if (list[listUsed] == NULL)
+	{
+		fprintf(stderr, "No memory for file name\n");
+
+		return FALSE;
+	}
+
+	/*
+	 * Increment the amount of space used.
+	 */
+	listUsed++;
+
+	return TRUE;
+}
+
+
+/*
+ * Free all of the names from the list of file names.
+ */
+static void
+clearListNames(void)
+{
+	while (listUsed > 0)
+	{
+		listUsed--;
+
+		free(list[listUsed]);
+	}
+}
+
+/* END CODE */

src/sash/dirent.h

@@ -0,0 +1,10 @@
+#ifndef DIRENT_H_
+#define DIRENT_H_
+
+typedef struct {} DIR;
+
+struct dirent {
+	char *d_name;
+};
+
+#endif // DIRENT_H_

src/sash/sash.1

@@ -0,0 +1,591 @@
+.TH SASH 1
+.SH NAME
+sash \- stand-alone shell with built-in commands
+.SH SYNOPSYS
+.B sash [-c command] [-f fileName ] [-p prompt] [-q] [-a]
+.SH DESCRIPTION
+The
+.B sash
+program is a stand-alone shell which is useful for recovering from certain
+types of system failures.
+In particular, it was created in order to cope with the problem of
+missing shared libraries or important executables.
+.PP
+.B Sash
+can execute external programs, as in any shell.  There are no restrictions
+on these commands, as the standard shell is used to execute them if there
+are any non-wildcard meta-characters in the command.
+.PP
+More importantly, however,
+is that many of the standard system commands are built-in to
+.BR sash .
+These built-in commands are:
+.PP
+.nf
+     -ar, -chattr, -chgrp, -chmod, -chown, -chroot, -cmp,
+     -cp, -dd, -echo, -ed, -grep, -file, -find, -gunzip,
+     -gzip, -kill, -losetup, -ln, -ls, -lsattr, -mkdir,
+     -mknod, -more, -mount, -mv, -pivot_root, -printenv, -pwd,
+     -rm, -rmdir, -sum, -sync, -tar, -touch, -umount, -where
+.fi
+.PP
+These commands are generally similar to the standard programs with similar
+names.  However, they are simpler and cruder than the external programs,
+and so many of the options are not implemented.  The restrictions for each
+built-in command are described later.
+.PP
+The built-in commands which correspond to external programs begin with a
+dash character in order to distinguish them from the external programs.
+So typing "ls", for example, will attempt to run the real
+.B ls
+program.
+If "-ls" is typed, then the built-in command which mimics
+.B ls
+is called.
+.PP
+For the built-in commands, file names are expanded so that asterisks,
+question marks, and characters inside of square brackets are recognised
+and are expanded.
+Arguments can be quoted using single quotes, double quotes, or backslashes.
+However, no other command line processing is performed.
+This includes specifying of file redirection, and the specifying of a pipeline.
+.PP
+If an external program is non-existant or fails to run correctly, then
+the "alias" built-in command may be used to redefine the standard command
+so that it automatically runs the built-in command instead.  For example,
+the command "alias ls -ls" redefines "ls" to run the built-in command.
+This saves you the pain of having to remember to type the leading dash
+all of the time.
+If many external programs will not run, then the "aliasall" command may
+be useful to create multiple aliases.
+.PP
+The "help" command will list all of the built-in commands in
+.B sash .
+If an argument is given, it will list only those built-in commands
+which contain the given argument as a sub-string.
+Each built-in command is described below in more detail.
+.PP
+.TP
+.B alias [name [command]]
+If
+.I name
+and
+.I command
+are provided, this defines an alias for a command with the specified name
+which executes the specified command with possible arguments.
+Arguments containing wildcards can be quoted in order to defer their
+expansion until the alias is invoked.
+If just
+.I name
+is provided, then the definition
+of the specified command alias is displayed.  If nothing is provided,
+then the definitions of all aliases are displayed.
+.TP
+.B aliasall
+This defines aliases for all of the built-in commands that start with
+dashes to the corresponding names without the dashes.
+This may be useful when the system is so corrupted that no external
+programs may be executed at all.
+.TP
+.B -ar [txp][v] arfile [filename]...
+List or extract files from an ar archive.
+The arfile argument specifies a file name which contains the archive.
+If no additional filenames are specified, then all files in the archive are
+operated on.
+Otherwise, only those archive members which have the same name 
+as one of the additional filenames are operated on.
+Filenames which do not appear in the archive are ignored.
+Archives cannot be created or modified.
+The archiver correctly handles 4.0BSD archives,
+and understands both the SysV and 4.4BSD extensions for long file names.
+The extended pseudo-BSD formats are not supported;
+nor are the two antediluvian binary formats derived from V7 and earlier.
+(The GNU archiver normally creates archives in the 4.0BSD format with
+SysV extensions.)
+.TP
+.B cd [dirName]
+If
+.I dirName
+is provided, then the current directory is changed to the
+dirName.  If
+.I dirName
+is absent, then the current directory is changed
+to the user's home directory (value of the $HOME environment variable).
+.TP
+.B -chattr [+i] [-i] [+a] [-a] fileName ...
+Change the attributes of the specified files on an ext2 or ext3 file system.
+Using a plus sign adds the specified attribute for the files.
+Using a minus sign removes the specified attributes for the files.
+The 'i' attribute makes a file immutable so that it cannot be changed.
+The 'a' attribute makes a file append-only.
+This command is only available on Linux.
+.TP
+.B -chgrp gid fileName ...
+Change the group id for the specified list of files.  The
+.I gid
+can
+either be a group name, or a decimal value.
+.TP
+.B -chmod mode fileName ...
+Change the mode of the specified list of files.  The
+.I mode
+argument
+can only be an octal value.
+.TP
+.B -chown uid fileName ...
+Change the owner id for the specified list of files.  The
+.I uid
+can
+either be a user name, or a decimal value.
+.TP
+.B -chroot path
+Changes  the  root  directory to that specified in
+.I path.
+This directory
+will be used for path  names  beginning with /. The root directory is
+inherited by all children of the current process.
+.TP
+.B -cmp fileName1 fileName2
+Determines whether or not the specified file names have identical data.
+This says that the files are links to each other, are different sizes,
+differ at a particular byte number, or are identical.
+.TP
+.B -cp srcName ... destName
+Copies one or more files from the
+.I srcName
+to the
+.IR destName .
+If more
+than one srcName is given, or if destName is a directory, then all
+the srcNames are copied into the destName directory with the same
+names as the srcNames.
+.TP
+.B -dd if=name of=name [bs=n] [count=n] [skip=n] [seek=n]
+Copy data from one file to another with the specified parameters.
+The
+.I if
+and
+.I of
+arguments must be provided, so stdin and stdout cannot
+be specified.  The
+.I bs
+argument is the block size, and is a numeric
+value (which defaults to 512 bytes).
+.I Count
+is the number of blocks
+to be copied (which defaults to end of file for the input file).
+.I Skip
+is the number of blocks to ignore before copying (seek is used
+if possible, and the default is 0).
+.I Seek
+is the number of blocks to
+seek in the output file before writing (and defaults to 0).  Any of
+the numeric decimal values can have one or more trailing letters
+from the set 'kbw', which multiplies the value by 1024, 512, and 2
+respectively.  The command reports the number of full blocks read
+and written, and whether or not any partial block was read or written.
+.TP
+.B -echo [args] ...
+Echo the arguments to the -echo command.  Wildcards are expanded,
+so this is a convenient way to get a quick list of file names in a directory.
+The output is always terminated with a newline.
+.TP
+.B -ed [fileName]
+Edit the specified file using line-mode commands.  The following
+.B ed
+commands are provided: = c r w i a d p l s f k z and q.
+Line numbers can be constants, ".", "$", "'x", 
+.RI / string /
+and simple
+arithmetic combinations of these.  The substitute command and the
+search expression can only use literal strings.  There are some
+small differences in the way that some commands behave.
+.TP
+.B exec fileName [args]
+Execute the specified program with the specified arguments.
+This replaces
+.B sash
+completely by the executed program.
+.TP
+.B exit
+Quit from
+.BR sash .
+.TP
+.B -file fileName ...
+Examine the specified files and print out their file type.
+This indicates whether the files are regular files or not,
+whether they contain printable text or shell scripts,
+are executables, or contain binary data.
+.TP
+.B -find dirName [-xdev] [-type chars] [-name pattern] [-size minSize]
+Find all files contained within the specified directory
+tree which meet all of the specified conditions.
+The -xdev option prevents crossing of mount points.
+The -name option specifies a wildcard pattern to match the last
+component of the file names.
+The -type option specifies that the files must have a type
+matching the specified list from the set: f d c b p s l.
+These represent regular files, directories, character devices,
+block devices, named pipes, sockets, and symbolic links.
+The -size option specifies that the files must be regular files or
+directories which contain at least the specified number of bytes.
+.TP
+.B -grep [-in] word fileName ...
+Display lines of the specified files which contain the given word.
+If only one file name is given, then only the matching lines are
+printed.  If multiple file names are given, then the file names are
+printed along with the matching lines.
+.I Word
+must be a single word,
+(ie, not a regular expression).  If -i is given, then case is
+ignored when doing the search.  If -n is given, then the line
+numbers of the matching lines are also printed.
+.TP
+.B -gunzip inputFileName ... [-o outputPath]
+Uncompress one or more files that had been compressed using the
+.I gzip
+or
+.I compress
+algorithms.
+If the -o option is not given,
+then each of the input file names must have one of the
+extensions ".gz", ".tgz", or ".Z",
+and those files will be replaced by the uncompressed versions of those files.
+The original files will be deleted after the output files have been
+successfully created.
+The uncompressed versions of the files have the same names as the original
+file names, except for a simple modification of their extensions.
+If an extension is ".tgz", then the extension is replaced by ".tar".
+Otherwise, the ".gz" or ".Z" extension is removed.
+.sp
+If the -o option is given, then the input files will not be deleted,
+and the uncompressed versions of the files will be created as specified
+by
+.IR outputPath .
+If the output path is a directory, then the uncompressed versions of the
+input files will be placed in that directory with their file names
+modified as described above, or with the same name if the input file name
+does not have one of the special extensions.
+If the output path is a regular file, then only one input file is allowed,
+and the uncompressed version of that input file is created as the output
+path exactly as specified.
+If the output path is a block or character device, then the uncompressed
+versions of the input files are concatenated to the device.
+.sp
+This command is only available if
+.B sash
+was compiled to use the gzip library.
+.TP
+.B -gzip inputFileName ... [-o outputPath]
+Compresses one or more files using the
+.I gzip
+algorithm.
+If the -o option is not given,
+then each of the input file names will be replaced by the compressed
+versions of those files,
+The original files will be deleted after the output files have been
+successfully created.
+The compressed versions of the files have the same names as the original
+file names, except for a simple modification of the extensions.
+If an extension is ".tar", then the extension is replaced by ".tgz".
+Otherwise, the ".gz" extension is added.
+.sp
+If the -o option is given, then the input files will not be deleted,
+and the compressed versions of the files will be created as specified
+by
+.IR outputPath .
+If the output path is a directory, then the compressed versions of the
+input files will be placed in that directory with their file names
+modified as described above.
+If the output path is not a directory, then only one input file is allowed,
+and the compressed version of that input file is created as the output
+path exactly as specified.
+.sp
+This command is only available if
+.B sash
+was compiled to use the gzip library.
+.TP
+.B help [word]
+Displays a list of built-in commands along with their usage strings.
+If a word is given,
+then just those commands whose name or usage contains the word is displayed.
+If a word is specified which exactly matches a built-in command name,
+then a short description of the command and its usage is given.
+.TP
+.B -kill [-signal] pid ...
+Sends the specified signal to the specified list of processes.
+.I Signal
+is a numeric value, or one of the special values HUP, INT,
+QUIT, KILL, TERM, STOP, CONT, USR1 or USR2.
+If no signal is specified then SIGTERM is used.
+.TP
+.B -losetup [-d] loopDev [file]
+Associates loopback devices with files on the system. If
+.I -d
+is not given,
+the loopback device
+.I loopDev
+is associated with
+.I file.
+If
+.I -d
+is given,
+.I loopDev
+is unassociated with the file it's currently configured for.
+.TP
+.B -ln [-s] srcName ... destName
+Links one or more files from the
+.I srcName
+to the specified
+.IR destName .
+If there are
+multiple srcNames, or destName is a directory, then the link is
+put in the destName directory with the same name as the source name.
+The default links are hard links.  Using -s makes symbolic links.
+For symbolic links, only one srcName can be specified.
+.TP
+.B -ls [-lidFC] fileName ...
+Display information about the specified list of file names.
+The normal listing is simply a list of file names, one per line.
+The options available are -l, -n, -i, -d, and -F.
+The -l option produces a long listing giving the normal 'ls' information.
+The -n option is like -l except that numeric user and group ids are shown.
+The -i option displays the inode numbers of the files.
+The -d option displays information about a directory, instead of the
+files within it.
+The -F option appends a slash or asterisk to the file name if the file
+is a directory or is executable.
+The -C option displays the file names in a multi-column format.
+The width of the output is calculated using the COLS environment variable.
+.TP
+.B -lsattr fileName ...
+Display attributes for the specified files on an ext2 or ext3 file system.
+The letter 'i' indicates that the file is immutable and cannot change.
+The letter 'a' indicates that the file is append-only.
+Dashes are shown where the attributes are not set.
+This command is only available on Linux.
+.TP
+.B -mkdir dirName ...
+Creates the specified directories.  They are created with the
+default permissions.
+.TP
+.B -mknod fileName type major minor
+Creates a special device node, either a character file or a block
+file.
+.I Filename
+is the name of the node.
+.I Type
+is either 'c' or 'd'.
+.I Major
+is the major device number.
+.I Minor
+is the minor device number.
+Both of these numbers are decimal.
+.TP
+.B -more fileName ...
+Type out the contents of the specified file names, one page at a
+time.  For each page displayed, you can type 'n' and a return to go
+to the next file, 'q' and a return to quit the command completely,
+or just a return to go to the next page.  The environment variables
+LINES and COLS can be used to set the page size.
+.TP
+.B -mount [-t type] [-r] [-s] [-e] [-m] devName dirName
+Mount a filesystem on a directory name.
+The -t option specifies the type of filesystem being mounted,
+and defaults to "ext3" for Linux and "ffs" for BSD.
+The -r option indicates to mount the filesystem read-only.
+The -s option indicates to mount the filesystem no-suid.
+The -e option indicates to mount the filesystem no-exec.
+The -m option indicates to remount an already mounted filesystem.
+The -m option is only available on Linux.
+.TP
+.B -mv srcName ... destName
+Moves one or more files from the
+.I srcName
+to the
+.IR destName .
+If multiple srcNames are given, or if destName is a directory, then
+the srcNames are copied into the destination directory with the
+same names as the srcNames.  Renames are attempted first, but if
+this fails because of the files being on different filesystems,
+then copies and deletes are done instead.
+.TP
+.B -pivot_root newRoot putOld
+Moves the root file system of the current process to the directory
+.I putOld
+and makes
+.I newRoot
+the  new root file system of the current process.
+.TP
+.B -printenv [name]
+If
+.I name
+is not given, this prints out the values of all the current
+environment variables.  If
+.I name
+is given, then only that environment variable value is printed.
+.TP
+.B prompt [word] ...
+Sets the prompt string that is displayed before reading of a
+command.  A space is always added to the specified prompt.
+.TP
+.B -pwd
+Prints the current working directory.
+.TP
+.B quit
+Exits from
+.BR sash .
+.TP
+.B -rm fileName ...
+Removes one or more files.
+.TP
+.B -rmdir dirName ...
+Removes one or more directories.  The directories must be empty
+for this to be successful.
+.TP
+.B setenv name value
+Set the value of an environment variable.
+.TP
+.B source fileName
+Execute commands which are contained in the specified file name.
+.TP
+.B -sum fileName ...
+Calculates checksums for one or more files.
+This is the 16 bit checksum compatible with the BSD sum program.
+.TP
+.B -sync
+Do a "sync" system call to force dirty blocks out to the disk.
+.TP
+.B -tar [ctxv]f tarFileName [fileName] ...
+Create, list or extract files from a tar archive.
+The f option must be specified, and accepts a device or file name
+argument which contains the tar archive.
+When creating, at least one file name must be specified to be stored.
+If a file name is a directory, then all the files and directories
+within the directory are stored.
+Linked files and other special file types are not handled properly.
+When listing or extracting files, only those files starting with
+the specified file names are processed.
+If no file names are specified, then all files in the archive are processed.
+Leading slashes in the tar archive file names are always removed so that you
+might need to cd to "/" to restore files which had absolute paths.
+.TP
+.B -touch fileName ...
+Updates the modify times of the specifed files.  If a file does not
+exist, then it will be created with the default protection.
+.TP
+.B umask [mask]
+If
+.I mask
+is given, sets the "umask" value used for initializing the
+permissions of newly created files.  If
+.I mask
+is not given, then the
+current umask value is printed.  The mask is an octal value.
+.TP
+.B -umount [-f] fileName
+Unmounts a file system.  The file name can either be the device name
+which is mounted, or else the directory name which the file system
+is mounted onto.
+The -f option unmounts the filesystem even if it is being used.
+The -f option is only available on BSD.
+.TP
+.B unalias name
+Remove the definition for the specified alias.
+.TP
+.B -where program
+Prints out all of paths defined by the PATH environment variable where the
+specified program exists.  If the program exists but cannot be executed,
+then the reason is also printed.
+.SH OPTIONS
+There are several command line options to
+.BR sash .
+.PP
+The -c option executes the next argument as a command (including embedded
+spaces to separate the arguments of the command), and then exits.
+.PP
+The -f option executes the commands contained in the file name specified
+by the next argument, and then exits.
+This feature can be used to create executable scripts for
+.B sash
+by starting the script file with a line similar to:
+.nf
+	#! /bin/sash -f
+.fi
+.PP
+The -p option takes the next argument as the prompt string to be used
+when prompting for commands.
+.PP
+The -q option makes
+.B sash
+quiet, which simply means that it doesn't print its introduction line
+when it starts.
+This option is also implied if the -c or -f options are used.
+.PP
+The -a option creates aliases for the built-in commands so
+that they replace the corresponding standard commands.
+This is the same result as if the 'aliasall' command was used.
+.SH SYSTEM RECOVERY
+This section contains some useful information about using
+.B sash
+with
+.B lilo
+to perform system recovery in some situations.
+Similar concepts should exist for other boot loaders and operating systems.
+.PP
+When important shared libraries are being upgraded,
+it might be a good idea to have
+.B sash
+already running on a console by itself.
+Then if there is a problem with the shared libraries
+.B sash
+will be unaffected and you may be able to use it to fix the problem.
+.PP
+If a problem with the system shows up at boot time so that you cannot
+enter multi-user mode and log in,
+then you can first try booting into single-user mode by adding the
+.I single
+keyword after your kernel image name at the
+.B lilo
+prompt.
+If you manage to reach a shell prompt, then you can run
+.B sash
+from that shell (if necessary).
+One reason for doing this is that you might need to use the
+.B -mount
+command with the -m option to remount the root file system
+so that it can be modified.
+.PP
+If you cannot reach the shell in single-user mode,
+then you can try running sash directly as a replacement for the init process.
+This is done by adding the
+.I init=/bin/sash
+keyword after your kernel image name at the
+.B lilo
+prompt.
+When this is done, then the use of the
+.B aliasall
+command might be useful to reduce attempts to access the root file system
+when running commands.
+.PP
+If your root file system is so corrupted that you cannot get
+.B sash
+to run at all, then you will have to resort to a system recovery floppy.
+.SH WARNINGS
+.B Sash
+should obviously be linked statically, otherwise its purpose is lost.
+Note that even if the rest of the program is linked statically, the
+password and group lookup routines in the C library can still be dynamic.
+For that reason, if there are problems then it might be necessary to
+only use numeric ids for the -chown and -chgrp commands and to use
+the -n option instead of -l for the -ls command.
+.PP
+Several other system commands might be necessary for system recovery,
+but aren't built-in to
+.BR sash .
+.SH AUTHOR
+.nf
+David I. Bell
+dbell@tip.net.au
+5 March 2014
+.fi

src/sash/sash.h

@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2014 by David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * Definitions for stand-alone shell for system maintainance for Linux.
+ */
+
+#ifndef	SASH_H
+#define	SASH_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <memory.h>
+#include <time.h>
+#include <ctype.h>
+
+#if __OpenBSD__
+#include <sys/param.h>
+#endif
+
+#if __Linux__
+#include <malloc.h>
+#endif
+
+
+#define	PATH_LEN	1024
+#define	CMD_LEN		10240
+#define	ALIAS_ALLOC	20
+#define	EXPAND_ALLOC	1024
+#define	STDIN		0
+#define	STDOUT		1
+#define	MAX_SOURCE	10
+#define	BUF_SIZE	8192
+
+
+#define	isBlank(ch)	(((ch) == ' ') || ((ch) == '\t'))
+#define	isDecimal(ch)	(((ch) >= '0') && ((ch) <= '9'))
+#define	isOctal(ch)	(((ch) >= '0') && ((ch) <= '7'))
+#define	isWildCard(ch)	(((ch) == '*') || ((ch) == '?') || ((ch) == '['))
+
+#ifndef MAX
+#define MAX(x, y)	((x) > (y) ? (x) : (y))
+#endif
+#ifndef MIN
+#define MIN(x, y)	((x) < (y) ? (x) : (y))
+#endif
+
+typedef	int	BOOL;
+
+#define	FALSE	((BOOL) 0)
+#define	TRUE	((BOOL) 1)
+
+
+/*
+ * Built-in command functions.
+ */
+extern	int	do_alias(int argc, const char ** argv);
+extern	int	do_aliasall(int argc, const char ** argv);
+extern	int	do_cd(int argc, const char ** argv);
+extern	int	do_exec(int argc, const char ** argv);
+extern	int	do_exit(int argc, const char ** argv);
+extern	int	do_prompt(int argc, const char ** argv);
+extern	int	do_source(int argc, const char ** argv);
+extern	int	do_umask(int argc, const char ** argv);
+extern	int	do_unalias(int argc, const char ** argv);
+extern	int	do_help(int argc, const char ** argv);
+extern	int	do_ln(int argc, const char ** argv);
+extern	int	do_cp(int argc, const char ** argv);
+extern	int	do_mv(int argc, const char ** argv);
+extern	int	do_rm(int argc, const char ** argv);
+extern	int	do_chmod(int argc, const char ** argv);
+extern	int	do_mkdir(int argc, const char ** argv);
+extern	int	do_rmdir(int argc, const char ** argv);
+extern	int	do_mknod(int argc, const char ** argv);
+extern	int	do_chown(int argc, const char ** argv);
+extern	int	do_chgrp(int argc, const char ** argv);
+extern	int	do_sum(int argc, const char ** argv);
+extern	int	do_sync(int argc, const char ** argv);
+extern	int	do_printenv(int argc, const char ** argv);
+extern	int	do_more(int argc, const char ** argv);
+extern	int	do_cmp(int argc, const char ** argv);
+extern	int	do_touch(int argc, const char ** argv);
+extern	int	do_ls(int argc, const char ** argv);
+extern	int	do_dd(int argc, const char ** argv);
+extern	int	do_tar(int argc, const char ** argv);
+extern	int	do_ar(int argc, const char ** argv);
+extern	int	do_mount(int argc, const char ** argv);
+extern	int	do_umount(int argc, const char ** argv);
+extern	int	do_setenv(int argc, const char ** argv);
+extern	int	do_pwd(int argc, const char ** argv);
+extern	int	do_echo(int argc, const char ** argv);
+extern	int	do_kill(int argc, const char ** argv);
+extern	int	do_grep(int argc, const char ** argv);
+extern	int	do_file(int argc, const char ** argv);
+extern	int	do_find(int argc, const char ** argv);
+extern	int	do_ed(int argc, const char ** argv);
+extern	int	do_where(int argc, const char ** argv);
+
+#if	HAVE_GZIP
+extern	int	do_gzip(int argc, const char ** argv);
+extern	int	do_gunzip(int argc, const char ** argv);
+#endif
+
+#if	HAVE_LINUX_ATTR
+extern	int	do_lsattr(int argc, const char ** argv);
+extern	int	do_chattr(int argc, const char ** argv);
+#endif
+
+#if	HAVE_LINUX_CHROOT
+extern	int	do_chroot(int argc, const char ** argv);
+#endif
+
+#if	HAVE_LINUX_LOSETUP
+extern	int	do_losetup(int argc, const char ** argv);
+#endif
+
+#if	HAVE_LINUX_PIVOT
+extern	int	do_pivot_root(int argc, const char ** argv);
+extern  int	pivot_root(const char *new_root, const char *put_old);
+#endif
+
+
+/*
+ * Global utility routines.
+ */
+extern	const char *	modeString(int mode);
+extern	const char *	timeString(time_t timeVal);
+extern	BOOL		isDirectory(const char * name);
+extern	BOOL		isDevice(const char * name);
+extern	int		nameSort(const void * p1, const void * p2);
+extern	char *		getChunk(int size);
+extern	char *		chunkstrdup(const char *);
+extern	void		freeChunks(void);
+extern	int		trySystem(const char * cmd);
+extern	void		tryWrite(int fd, const char * buf, int len);
+extern	int		fullWrite(int fd, const char * buf, int len);
+extern	int		fullRead(int fd, char * buf, int len);
+extern	void		checkStatus(const char * name, int status);
+extern	BOOL		match(const char * text, const char * pattern);
+
+extern	const char *	buildName
+	(const char * dirName, const char * fileName);
+
+extern	BOOL	makeArgs
+	(const char * cmd, int * argcPtr, const char *** argvPtr);
+
+extern	BOOL	copyFile
+	(const char * srcName, const char * destName, BOOL setModes);
+
+extern	BOOL	makeString
+	(int argc, const char ** argv, char * buf, int bufLen);
+
+extern	int	expandWildCards
+	(const char * fileNamePattern, const char *** retFileTable);
+
+
+/*
+ * Global variable to indicate that an SIGINT occurred.
+ * This is used to stop processing.
+ */
+extern	BOOL	intFlag;
+
+#endif
+
+/* END CODE */

src/user/user.c

@@ -2,9 +2,6 @@
 #include "priv_gpio.h"
 #include <kernel/task.h>
 
-void task1(void);
-void task2(void);
-
 void user_delay(uint32_t ms)
 {
 	register uint32_t r1 asm("r1") = ms;
@@ -16,29 +13,32 @@ void user_delay(uint32_t ms)
 	" :: "r" (r1));
 }
 
+int fork(void)
+{
+	int result;
+	asm("\
+		mov r0, sp; \
+		svc 3; \
+		mov %0, r0; \
+	" : "=r" (result));
+	return result;
+}
+
 void user_main(void)
 {
 	gpio(GPIO_MODE, 5, OUTPUT);
-	task_start(task1, 512);
 
-	for (int i = 0; i < 8; i++) {
-		gpio(GPIO_OUT, 5, !(i & 1));
-		user_delay(200);
-	}
-}
-
-void task1(void)
-{
-	user_delay(400);
-	task_start(task2, 1024);
-}
-
-void task2(void)
-{
-	int state = 0;
-	user_delay(2500);
+	if (fork() == 0) {
 		while (1) {
-		gpio(GPIO_OUT, 5, state ^= 1);
+			gpio(GPIO_OUT, 5, 1);
+			user_delay(1000);
+		}
+	} else {
+		while (1) {
+			gpio(GPIO_OUT, 5, 0);
 			user_delay(500);
 		}
+	
 	}
+}
+