1 files changed, 85 insertions, 0 deletions
diff --git a/src/pdclib/functions/stdio/fseek.c b/src/pdclib/functions/stdio/fseek.c
new file mode 100644
index 0000000..54f4c4b
--- /dev/null
+++ b/src/pdclib/functions/stdio/fseek.c
@@ -0,0 +1,85 @@
+/* fseek( FILE *, long, int )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <stdio.h>
+
+#ifndef REGTEST
+
+#include "pdclib/_PDCLIB_glue.h"
+
+int fseek( struct _PDCLIB_file_t * stream, long offset, int whence )
+{
+    if ( stream->status & _PDCLIB_FWRITE )
+    {
+        if ( _PDCLIB_flushbuffer( stream ) == EOF )
+        {
+            return EOF;
+        }
+    }
+    stream->status &= ~ _PDCLIB_EOFFLAG;
+    if ( stream->status & _PDCLIB_FRW )
+    {
+        stream->status &= ~ ( _PDCLIB_FREAD | _PDCLIB_FWRITE );
+    }
+    return ( _PDCLIB_seek( stream, offset, whence ) != EOF ) ? 0 : EOF;
+}
+
+#endif
+
+#ifdef TEST
+
+#include "_PDCLIB_test.h"
+
+#include <string.h>
+
+int main( void )
+{
+    FILE * fh;
+    TESTCASE( ( fh = tmpfile() ) != NULL );
+    TESTCASE( fwrite( teststring, 1, strlen( teststring ), fh ) == strlen( teststring ) );
+    /* General functionality */
+    TESTCASE( fseek( fh, -1, SEEK_END ) == 0  );
+    TESTCASE( (size_t)ftell( fh ) == strlen( teststring ) - 1 );
+    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
+    TESTCASE( (size_t)ftell( fh ) == strlen( teststring ) );
+    TESTCASE( fseek( fh, 0, SEEK_SET ) == 0 );
+    TESTCASE( ftell( fh ) == 0 );
+    TESTCASE( fseek( fh, 5, SEEK_CUR ) == 0 );
+    TESTCASE( ftell( fh ) == 5 );
+    TESTCASE( fseek( fh, -3, SEEK_CUR ) == 0 );
+    TESTCASE( ftell( fh ) == 2 );
+    /* Checking behaviour around EOF */
+    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
+    TESTCASE( ! feof( fh ) );
+    TESTCASE( fgetc( fh ) == EOF );
+    TESTCASE( feof( fh ) );
+    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
+    TESTCASE( ! feof( fh ) );
+    /* Checking undo of ungetc() */
+    TESTCASE( fseek( fh, 0, SEEK_SET ) == 0 );
+    TESTCASE( fgetc( fh ) == teststring[0] );
+    TESTCASE( fgetc( fh ) == teststring[1] );
+    TESTCASE( fgetc( fh ) == teststring[2] );
+    TESTCASE( ftell( fh ) == 3 );
+    TESTCASE( ungetc( teststring[2], fh ) == teststring[2] );
+    TESTCASE( ftell( fh ) == 2 );
+    TESTCASE( fgetc( fh ) == teststring[2] );
+    TESTCASE( ftell( fh ) == 3 );
+    TESTCASE( ungetc( 'x', fh ) == 'x' );
+    TESTCASE( ftell( fh ) == 2 );
+    TESTCASE( fgetc( fh ) == 'x' );
+    TESTCASE( ungetc( 'x', fh ) == 'x' );
+    TESTCASE( ftell( fh ) == 2 );
+    TESTCASE( fseek( fh, 2, SEEK_SET ) == 0 );
+    TESTCASE( fgetc( fh ) == teststring[2] );
+    /* Checking error handling */
+    TESTCASE( fseek( fh, -5, SEEK_SET ) == -1 );
+    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
+    TESTCASE( fclose( fh ) == 0 );
+    return TEST_RESULTS;
+}
+
+#endif