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authorGravatar Rob Landley <rob@landley.net>2006-05-21 18:28:13 +0000
committerGravatar Rob Landley <rob@landley.net>2006-05-21 18:28:13 +0000
commitc020f5f518714af603488c7d9e6cc72543fabc49 (patch)
tree1030744a4f3b96c0d3d7498e65635f8ecc898f45 /coreutils/nohup.c
parent4148afe04975c6003bde330db2b074d49f25f5d3 (diff)
downloadbusybox-c020f5f518714af603488c7d9e6cc72543fabc49.tar.gz
busybox-c020f5f518714af603488c7d9e6cc72543fabc49.tar.bz2
New version of nohup that's much smaller, less paranoid, consistent,
vaguely portable, and licensed GPLv2 "or later".
Diffstat (limited to 'coreutils/nohup.c')
-rw-r--r--coreutils/nohup.c202
1 files changed, 36 insertions, 166 deletions
diff --git a/coreutils/nohup.c b/coreutils/nohup.c
index febaf547f..ea1c4c55a 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]);
}