--- /dev/null
+/* 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.
+
+ */
+
+/* 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 "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 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, mode_t mode)
+{
+ int fd;
+
+ close (desired_fd);
+ fd = open (file, flags, mode);
+ 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;
+ }
+}
+
+
+/* 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.
+
+ 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.
+
+ 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 (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;
+
+ 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, "/dev/null", O_WRONLY, 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_WRONLY | O_APPEND, S_IRUSR | S_IWUSR);
+
+ 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_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);
+ exit (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;
+
+ signal (SIGHUP, SIG_IGN);
+
+ {
+ char **cmd = argv + 1;
+
+ execvp (*cmd, cmd);
+
+ /* 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);
+
+ return (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
+ }
+}
+
projects / oweals / busybox.git / commitdiff