add libc building to agbcc.

libc/stdlib/system.c

@@ -0,0 +1,179 @@
+/*
+FUNCTION
+<<system>>---execute command string
+
+INDEX
+	system
+INDEX
+	_system_r
+
+ANSI_SYNOPSIS
+	#include <stdlib.h>
+	int system(char *<[s]>);
+
+	int _system_r(void *<[reent]>, char *<[s]>);
+
+TRAD_SYNOPSIS
+	#include <stdlib.h>
+	int system(<[s]>)
+	char *<[s]>;
+
+	int _system_r(<[reent]>, <[s]>)
+	char *<[reent]>;
+	char *<[s]>;
+
+DESCRIPTION
+
+Use <<system>> to pass a command string <<*<[s]>>> to <</bin/sh>> on
+your system, and wait for it to finish executing.
+
+Use `<<system(NULL)>>' to test whether your system has <</bin/sh>>
+available.
+
+The alternate function <<_system_r>> is a reentrant version.  The
+extra argument <[reent]> is a pointer to a reentrancy structure.
+
+RETURNS
+<<system(NULL)>> returns a non-zero value if <</bin/sh>> is available, and
+<<0>> if it is not.
+
+With a command argument, the result of <<system>> is the exit status
+returned by <</bin/sh>>.
+
+PORTABILITY
+ANSI C requires <<system>>, but leaves the nature and effects of a
+command processor undefined.  ANSI C does, however, specify that
+<<system(NULL)>> return zero or nonzero to report on the existence of
+a command processor.
+
+POSIX.2 requires <<system>>, and requires that it invoke a <<sh>>.
+Where <<sh>> is found is left unspecified.
+
+Supporting OS subroutines required: <<_exit>>, <<_execve>>, <<_fork_r>>,
+<<_wait_r>>.
+*/
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <_syslist.h>
+
+#if defined (unix) || defined (__CYGWIN32__)
+static int do_system ();
+#endif
+
+int
+_system_r (ptr, s)
+     struct _reent *ptr;
+     _CONST char *s;
+{
+#ifdef NO_EXEC
+  if (s == NULL)
+    return 0;
+  errno = ENOSYS;
+  return -1;
+#else
+
+  /* ??? How to handle (s == NULL) here is not exactly clear.
+     If _fork_r fails, that's not really a justification for returning 0.
+     For now we always return 0 and leave it to each target to explicitly
+     handle otherwise (this can always be relaxed in the future).  */
+
+#if defined (unix) || defined (__CYGWIN32__)
+  if (s == NULL)
+    return 1;
+  return do_system (ptr, s);
+#else
+  if (s == NULL)
+    return 0;
+  errno = ENOSYS;
+  return -1;
+#endif
+
+#endif
+}
+
+#ifndef _REENT_ONLY
+
+int
+system (s)
+     _CONST char *s;
+{
+  return _system_r (_REENT, s);
+}
+
+#endif
+
+#if defined (unix) && !defined (__CYGWIN32__)
+static int
+do_system (ptr, s)
+     struct _reent *ptr;
+     _CONST char *s;
+{
+  char *argv[4];
+  int pid, status;
+  extern char *environ[];
+
+  argv[0] = "sh";
+  argv[1] = "-c";
+  argv[2] = (char *) s;
+  argv[3] = NULL;
+
+  if ((pid = _fork_r (ptr)) == 0)
+    {
+      _execve ("/bin/sh", argv, environ);
+      exit (100);
+    }
+  else if (pid == -1)
+    return -1;
+  else
+    {
+      int rc = _wait_r (ptr, &status);
+      if (rc == -1)
+	return -1;
+      status = (status >> 8) & 0xff;
+      return status;
+    }
+}
+#endif
+
+#if defined (__CYGWIN32__)
+static int
+do_system (ptr, s)
+     struct _reent *ptr;
+     _CONST char *s;
+{
+  char *argv[4];
+  int pid, status;
+  extern char *environ[];
+
+  argv[0] = "sh";
+  argv[1] = "-c";
+  argv[2] = (char *) s;
+  argv[3] = NULL;
+
+  if ((pid = vfork ()) == 0)
+    {
+      /* ??? It's not clear what's the right path to take (pun intended :-).
+	 There won't be an "sh" in any fixed location so we need each user
+	 to be able to say where to find "sh".  That suggests using an
+	 environment variable, but after a few more such situations we may
+	 have too many of them.  */
+      char *sh = getenv ("SH_PATH");
+      if (sh == NULL)
+	sh = "/bin/sh";
+      _execve (sh, argv, environ);
+      exit (100);
+    }
+  else if (pid == -1)
+    return -1;
+  else
+    {
+      int rc = _wait (&status);
+      if (rc == -1)
+	return -1;
+      status = (status >> 8) & 0xff;
+      return status;
+    }
+}
+#endif