New version of nohup that's much smaller, less paranoid, consistent,

vaguely portable, and licensed GPLv2 "or later".

1 files changed, 36 insertions, 166 deletions

diff --git a/coreutils/nohup.c b/coreutils/nohup.c
index febaf54..ea1c4c5 100644
--- a/coreutils/nohup.c
+++ b/coreutils/nohup.c
@@ -1,185 +1,55 @@
-/* vi: set sw=4 ts=4: */
-/* nohup -- run a command immune to hangups, with output to a non-tty
-   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
-
-   Licensed under the GPL v2, see the file LICENSE in this tarball.
-
+/* vi:set ts=4: */
+/* nohup - invoke a utility immune to hangups.
+ * 
+ * Busybox version based on nohup specification at
+ * http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
+ * 
+ * Copyright 2006 Rob Landley <rob@landley.net>
+ * 
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-/* Written by Jim Meyering  */
-/* initial busybox port by Bernhard Fischer */
-
-#include <stdio_ext.h> /* __fpending */
-#include <stdio.h>
-#include <unistd.h>
 #include <fcntl.h>
-#include <sys/types.h>
-#include <signal.h>
-#include <errno.h>
-
+#include <unistd.h>
 #include "busybox.h"
-#define EXIT_CANNOT_INVOKE (126)
-#define NOHUP_FAILURE (127)
-#define EXIT_ENOENT NOHUP_FAILURE
-
 
-
-#if defined F_GETFD && defined F_SETFD
-static inline int set_cloexec_flag (int desc)
+int nohup_main(int argc, char *argv[])
 {
-	int flags = fcntl (desc, F_GETFD, 0);
-	if (0 <= flags) {
-		if (flags == (flags |= FD_CLOEXEC) ||
-			fcntl (desc, F_SETFD, flags) != -1) {
-			return 0;
-		}
-	}
-	return -1;
-}
-#else
-#define set_cloexec_flag(desc) (0)
-#endif
-
-static int fd_reopen (int desired_fd, char const *file, int flags)
-{
-	int fd;
-
-	close (desired_fd);
-	fd = open (file, flags | O_WRONLY, S_IRUSR | S_IWUSR);
-	if (fd == desired_fd || fd < 0)
-		return fd;
-	else {
-		int fd2 = fcntl (fd, F_DUPFD, desired_fd);
-		int saved_errno = errno;
-		close (fd);
-		errno = saved_errno;
-		return fd2;
-	}
-}
-
+	int temp, nullfd;
+	char *nohupout = "nohup.out", *home = NULL;
 
-/* Close standard output, exiting with status 'exit_failure' on failure.
-   If a program writes *anything* to stdout, that program should close
-   stdout and make sure that it succeeds before exiting.  Otherwise,
-   suppose that you go to the extreme of checking the return status
-   of every function that does an explicit write to stdout.  The last
-   printf can succeed in writing to the internal stream buffer, and yet
-   the fclose(stdout) could still fail (due e.g., to a disk full error)
-   when it tries to write out that buffered data.  Thus, you would be
-   left with an incomplete output file and the offending program would
-   exit successfully.  Even calling fflush is not always sufficient,
-   since some file systems (NFS and CODA) buffer written/flushed data
-   until an actual close call.
+	if (argc<2) bb_show_usage();
 
-   Besides, it's wasteful to check the return value from every call
-   that writes to stdout -- just let the internal stream state record
-   the failure.  That's what the ferror test is checking below.
+	nullfd = bb_xopen(bb_dev_null, O_WRONLY|O_APPEND);
+	// If stdin is a tty, detach from it.
 
-   It's important to detect such failures and exit nonzero because many
-   tools (most notably `make' and other build-management systems) depend
-   on being able to detect failure in other tools via their exit status.  */
-
-static void close_stdout (void)
-{
-	int prev_fail = ferror (stdout);
-	int none_pending = (0 == __fpending (stdout));
-	int fclose_fail = fclose (stdout);
+	if (isatty(0)) dup2(nullfd, 0);
 
-	if (prev_fail || fclose_fail) {
-		/* If ferror returned zero, no data remains to be flushed, and we'd
-		otherwise fail with EBADF due to a failed fclose, then assume that
-		it's ok to ignore the fclose failure.  That can happen when a
-		program like cp is invoked like this `cp a b >&-' (i.e., with
-		stdout closed) and doesn't generate any output (hence no previous
-		error and nothing to be flushed).  */
-		if ((fclose_fail ? errno : 0) == EBADF && !prev_fail && none_pending)
-			return;
+	// Redirect stdout to nohup.out, either in "." or in "$HOME".
 
-		bb_perror_msg_and_die(bb_msg_write_error);
-	}
-}
-
-
-int nohup_main (int argc, char **argv)
-{
-	int saved_stderr_fd;
-
-	if (argc < 2)
-		bb_show_usage();
-
-	bb_default_error_retval = NOHUP_FAILURE;
-
-	atexit (close_stdout);
-
-	/* If standard input is a tty, replace it with /dev/null.
-	 Note that it is deliberately opened for *writing*,
-	 to ensure any read evokes an error.  */
-	if (isatty (STDIN_FILENO))
-		fd_reopen (STDIN_FILENO, bb_dev_null, 0);
-
-	/* If standard output is a tty, redirect it (appending) to a file.
-	 First try nohup.out, then $HOME/nohup.out.  */
-	if (isatty (STDOUT_FILENO)) {
-		char *in_home = NULL;
-		char const *file = "nohup.out";
-		int fd = fd_reopen (STDOUT_FILENO, file, O_CREAT | O_APPEND);
-
-		if (fd < 0) {
-			if ((in_home = getenv ("HOME")) != NULL) {
-				in_home = concat_path_file(in_home, file);
-				fd = fd_reopen (STDOUT_FILENO, in_home, O_CREAT | O_APPEND);
+	if (isatty(1)) {
+		close(1);
+		if (open(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR) < 0) {
+			home = getenv("HOME");
+			if (home) {
+				home = concat_path_file(home, nohupout);
+				bb_xopen3(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR);
 			}
-			if (fd < 0) {
-				bb_perror_msg("failed to open '%s'", file);
-				if (in_home)
-					bb_perror_msg("failed to open '%s'",in_home);
-				return (NOHUP_FAILURE);
-			}
-			file = in_home;
-		}
-
-		umask (~(S_IRUSR | S_IWUSR));
-		bb_error_msg("appending output to '%s'", file);
-		if (ENABLE_FEATURE_CLEAN_UP)
-			free (in_home);
-	}
-
-	/* If standard error is a tty, redirect it to stdout.  */
-	if (isatty (STDERR_FILENO)) {
-	/* Save a copy of stderr before redirecting, so we can use the original
-	 if execve fails.  It's no big deal if this dup fails.  It might
-	 not change anything, and at worst, it'll lead to suppression of
-	 the post-failed-execve diagnostic.  */
-		saved_stderr_fd = dup (STDERR_FILENO);
-
-		if (0 <= saved_stderr_fd && set_cloexec_flag (saved_stderr_fd) == -1)
-			bb_perror_msg_and_die("failed to set the copy"
-					"of stderr to close on exec");
-
-		if (dup2 (STDOUT_FILENO, STDERR_FILENO) < 0) {
-			if (errno != EBADF)
-				bb_perror_msg_and_die("failed to redirect standard error");
-			close (STDERR_FILENO);
 		}
-	} else
-		saved_stderr_fd = STDERR_FILENO;
+	} else dup2(nullfd, 1);
 
-	signal (SIGHUP, SIG_IGN);
+	// If we have a tty on strderr, announce filename and redirect to stdout.
+	// Else redirect to /dev/null.
 
-	{
-	char **cmd = argv + 1;
+	temp = isatty(2);
+	if (temp) fdprintf(2,"Writing to %s\n", home ? home : nohupout);
+	dup2(temp ? 1 : nullfd, 2);
 
-	execvp (*cmd, cmd);
+	close(nullfd);
 
-	/* The execve failed.  Output a diagnostic to stderr only if:
-	   - stderr was initially redirected to a non-tty, or
-	   - stderr was initially directed to a tty, and we
-	   can dup2 it to point back to that same tty.
-	   In other words, output the diagnostic if possible, but only if
-	   it will go to the original stderr.  */
-	if (dup2 (saved_stderr_fd, STDERR_FILENO) == STDERR_FILENO)
-		bb_perror_msg("cannot run command '%s'",*cmd);
+	// Exec our new program.
 
-	return (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
-	}
+	execvp(argv[1],argv+1);
+	if (ENABLE_FEATURE_CLEAN_UP) free(home);
+	bb_error_msg_and_die("exec %s",argv[1]);
 }