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

vaguely portable, and licensed GPLv2 "or later".


git-svn-id: svn://busybox.net/trunk/busybox@15155 69ca8d6d-28ef-0310-b511-8ec308f3f277

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]);
 }