[svn-upgrade] Integrating new upstream version, shadow (19990709)

libmisc/shell.c

@@ -0,0 +1,126 @@
+/*
+ * Copyright 1989 - 1991, Julianne Frances Haugh
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Julianne F. Haugh nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include "rcsid.h"
+RCSID("$Id: shell.c,v 1.7 1998/12/28 20:34:53 marekm Exp $")
+
+#include <stdio.h>
+#include <errno.h>
+#include "prototypes.h"
+#include "defines.h"
+
+
+extern char **newenvp;
+extern size_t newenvc;
+
+/*
+ * shell - execute the named program
+ *
+ *	shell begins by trying to figure out what argv[0] is going to
+ *	be for the named process.  The user may pass in that argument,
+ *	or it will be the last pathname component of the file with a
+ *	'-' prepended.  The first attempt is to just execute the named
+ *	file.  If the errno comes back "ENOEXEC", the file is assumed
+ *	at first glance to be a shell script.  The first two characters
+ *	must be "#!", in which case "/bin/sh" is executed to process
+ *	the file.  If all that fails, give up in disgust ...
+ */
+
+void
+shell(const char *file, const char *arg)
+{
+	char arg0[1024];
+	int err;
+
+	if (file == (char *) 0)
+		exit (1);
+
+	/*
+	 * The argv[0]'th entry is usually the path name, but
+	 * for various reasons the invoker may want to override
+	 * that.  So, we determine the 0'th entry only if they
+	 * don't want to tell us what it is themselves.
+	 */
+
+	if (arg == (char *) 0) {
+		snprintf(arg0, sizeof arg0, "-%s", Basename((char *) file));
+		arg = arg0;
+	}
+#ifdef DEBUG
+	printf (_("Executing shell %s\n"), file);
+#endif
+
+	/*
+	 * First we try the direct approach.  The system should be
+	 * able to figure out what we are up to without too much
+	 * grief.
+	 */
+
+	execle (file, arg, (char *) 0, newenvp);
+	err = errno;
+
+	/* Linux handles #! in the kernel, and bash doesn't make
+	   sense of "#!" so it wouldn't work anyway...  --marekm */
+#ifndef __linux__
+	/*
+	 * It is perfectly OK to have a shell script for a login
+	 * shell, and this code attempts to support that.  It
+	 * relies on the standard shell being able to make sense
+	 * of the "#!" magic number.
+	 */
+
+	if (err == ENOEXEC) {
+		FILE	*fp;
+
+		if ((fp = fopen (file, "r"))) {
+			if (getc (fp) == '#' && getc (fp) == '!') {
+				fclose (fp);
+				execle ("/bin/sh", "sh",
+					file, (char *) 0, newenvp);
+				err = errno;
+			} else {
+				fclose (fp);
+			}
+		}
+	}
+#endif
+
+	/*
+	 * Obviously something is really wrong - I can't figure out
+	 * how to execute this stupid shell, so I might as well give
+	 * up in disgust ...
+	 */
+
+	snprintf(arg0, sizeof arg0, _("Cannot execute %s"), file);
+	errno = err;
+	perror(arg0);
+	exit(1);
+}