- add applet nohup(1)

5 files changed, 205 insertions, 0 deletions

diff --git a/coreutils/Config.in b/coreutils/Config.in
index 9e06c0d80..f92cd0d31 100644
--- a/coreutils/Config.in
+++ b/coreutils/Config.in
@@ -361,6 +361,12 @@ config CONFIG_NICE
         help
           nice runs a program with modified scheduling priority.
 
+config CONFIG_NOHUP
+        bool "nohup"
+        default n
+        help
+          run a command immune to hangups, with output to a non-tty.
+
 config CONFIG_OD
         bool "od"
         default n
diff --git a/coreutils/Makefile.in b/coreutils/Makefile.in
index c46dcbacb..2dc9ebabc 100644
--- a/coreutils/Makefile.in
+++ b/coreutils/Makefile.in
@@ -60,6 +60,7 @@ COREUTILS-$(CONFIG_MKFIFO)    += mkfifo.o
 COREUTILS-$(CONFIG_MKNOD)     += mknod.o
 COREUTILS-$(CONFIG_MV)        += mv.o
 COREUTILS-$(CONFIG_NICE)      += nice.o
+COREUTILS-$(CONFIG_NOHUP)     += nohup.o
 COREUTILS-$(CONFIG_OD)        += od.o
 COREUTILS-$(CONFIG_PRINTENV)  += printenv.o
 COREUTILS-$(CONFIG_PRINTF)    += printf.o
diff --git a/coreutils/nohup.c b/coreutils/nohup.c
new file mode 100644
index 000000000..407cf00ea
--- /dev/null
+++ b/coreutils/nohup.c
@@ -0,0 +1,188 @@
+/* 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);
+        }
+}
+
diff --git a/include/applets.h b/include/applets.h
index 916597078..56ec0a6de 100644
--- a/include/applets.h
+++ b/include/applets.h
@@ -462,6 +462,9 @@
 #ifdef CONFIG_NICE
         APPLET(nice, nice_main, _BB_DIR_BIN, _BB_SUID_NEVER)
 #endif
+#ifdef CONFIG_NOHUP
+        APPLET(nohup, nohup_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
+#endif
 #ifdef CONFIG_NSLOOKUP
         APPLET(nslookup, nslookup_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
 #endif
diff --git a/include/usage.h b/include/usage.h
index 43b6f7048..f702729e5 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2035,6 +2035,13 @@
         "Options:\n" \
         "\t-n ADJUST\tAdjust the scheduling priority by ADJUST"
 
+#define nohup_trivial_usage \
+        "COMMAND [ARGS]"
+#define nohup_full_usage \
+        "run a command immune to hangups, with output to a non-tty"
+#define nohup_example_usage \
+        "$ nohup make &"
+
 #define nslookup_trivial_usage \
         "[HOST] [SERVER]"
 #define nslookup_full_usage \