1 files changed, 84 insertions, 0 deletions
diff --git a/src/pdclib/platform/example/include/signal.h b/src/pdclib/platform/example/include/signal.h
new file mode 100644
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--- /dev/null
+++ b/src/pdclib/platform/example/include/signal.h
@@ -0,0 +1,84 @@
+/* Signal handling <string.h>
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#ifndef _PDCLIB_SIGNAL_H
+#define _PDCLIB_SIGNAL_H _PDCLIB_SIGNAL_H
+
+#include "pdclib/_PDCLIB_config.h"
+
+/* Signals ------------------------------------------------------------------ */
+
+/* A word on signals, to the people using PDCLib in their OS projects.
+
+   The definitions of the C standard leave about everything that *could* be
+   useful to be "implementation defined". Without additional, non-standard
+   arrangements, it is not possible to turn them into a useful tool.
+
+   This example implementation chose to "not generate any of these signals,
+   except as a result of explicit calls to the raise function", which is
+   allowed by the standard but of course does nothing for the usefulness of
+   <signal.h>.
+
+   A useful signal handling would:
+   1) make signal() a system call that registers the signal handler with the OS
+   2) make raise() a system call triggering an OS signal to the running process
+   3) make provisions that further signals of the same type are blocked until
+      the signal handler returns (optional for SIGILL)
+*/
+
+/* These are the values used by Linux. */
+
+/* Abnormal termination / abort() */
+#define SIGABRT 6
+/* Arithmetic exception / division by zero / overflow */
+#define SIGFPE  8
+/* Illegal instruction */
+#define SIGILL  4
+/* Interactive attention signal */
+#define SIGINT  2
+/* Invalid memory access */
+#define SIGSEGV 11
+/* Termination request */
+#define SIGTERM 15
+
+/* The following should be defined to pointer values that could NEVER point to
+   a valid signal handler function. (They are used as special arguments to
+   signal().) Again, these are the values used by Linux.
+*/
+#define SIG_DFL (void (*)( int ))0
+#define SIG_ERR (void (*)( int ))-1
+#define SIG_IGN (void (*)( int ))1
+
+typedef _PDCLIB_sig_atomic sig_atomic_t;
+
+/* Installs a signal handler "func" for the given signal.
+   A signal handler is a function that takes an integer as argument (the signal
+   number) and returns void.
+
+   Note that a signal handler can do very little else than:
+   1) assign a value to a static object of type "volatile sig_atomic_t",
+   2) call signal() with the value of sig equal to the signal received,
+   3) call _Exit(),
+   4) call abort().
+   Virtually everything else is undefind.
+
+   The signal() function returns the previous installed signal handler, which
+   at program start may be SIG_DFL or SIG_ILL. (This implementation uses
+   SIG_DFL for all handlers.) If the request cannot be honored, SIG_ERR is
+   returned and errno is set to an unspecified positive value.
+*/
+void (*signal( int sig, void (*func)( int ) ) )( int );
+
+/* Raises the given signal (executing the registered signal handler with the
+   given signal number as parameter).
+   This implementation does not prevent further signals of the same time from
+   occuring, but executes signal( sig, SIG_DFL ) before entering the signal
+   handler (i.e., a second signal before the signal handler re-registers itself
+   or SIG_IGN will end the program).
+   Returns zero if successful, nonzero otherwise. */
+int raise( int sig );
+
+#endif