hush/libbb/vfork_daemon_rexec.c

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/* vi: set sw=4 ts=4: */
/*
* Rexec program for system have fork() as vfork() with foreground option
*
* Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru>
* Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu>
*
* daemon() portion taken from uClibc:
*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Modified for uClibc by Erik Andersen <andersee@debian.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <paths.h>
#include "busybox.h" /* for struct BB_applet */
/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
* -1 for failure. Runs argv[0], searching path if that has no / in it. */
pid_t spawn(char **argv)
{
/* Compiler should not optimize stores here */
volatile int failed;
pid_t pid;
// Ain't it a good place to fflush(NULL)?
/* Be nice to nommu machines. */
failed = 0;
pid = vfork();
if (pid < 0) /* error */
return pid;
if (!pid) { /* child */
/* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
BB_EXECVP(argv[0], argv);
/* We are (maybe) sharing a stack with blocked parent,
* let parent know we failed and then exit to unblock parent
* (but don't run atexit() stuff, which would screw up parent.)
*/
failed = errno;
_exit(111);
}
/* parent */
/* Unfortunately, this is not reliable: according to standards
* vfork() can be equivalent to fork() and we won't see value
* of 'failed'.
* Interested party can wait on pid and learn exit code.
* If 111 - then it (most probably) failed to exec */
if (failed) {
errno = failed;
return -1;
}
return pid;
}
/* Die with an error message if we can't spawn a child process. */
pid_t xspawn(char **argv)
{
pid_t pid = spawn(argv);
if (pid < 0)
bb_perror_msg_and_die("%s", *argv);
return pid;
}
// Wait for the specified child PID to exit, returning child's error return.
int wait4pid(int pid)
{
int status;
if (pid <= 0) {
/*errno = ECHILD; -- wrong. */
/* we expect errno to be already set from failed [v]fork/exec */
return -1;
}
if (waitpid(pid, &status, 0) == -1)
return -1;
if (WIFEXITED(status))
return WEXITSTATUS(status);
if (WIFSIGNALED(status))
return WTERMSIG(status) + 1000;
return 0;
}
int wait_nohang(int *wstat)
{
return waitpid(-1, wstat, WNOHANG);
}
int wait_pid(int *wstat, int pid)
{
int r;
do
r = waitpid(pid, wstat, 0);
while ((r == -1) && (errno == EINTR));
return r;
}
int spawn_and_wait(char **argv)
{
int rc;
if (ENABLE_FEATURE_EXEC_PREFER_APPLETS) {
const struct BB_applet *a = find_applet_by_name(argv[0]);
if (a && (a->nofork
#ifndef BB_NOMMU
|| a->noexec /* NOEXEC cannot be used on NOMMU */
#endif
)) {
int argc = 1;
char **pp = argv;
while (*++pp)
argc++;
#ifndef BB_NOMMU
if (a->nofork)
#endif
{
int old_sleep = die_sleep;
die_sleep = -1; /* special flag */
/* sleep_and_die() checks for it */
rc = setjmp(die_jmp);
if (!rc) {
const struct BB_applet *old_a = current_applet;
current_applet = a;
applet_name = a->name;
// what else should we save/restore?
rc = a->main(argc, argv);
current_applet = old_a;
applet_name = old_a->name;
}
die_sleep = old_sleep;
return rc;
}
#ifndef BB_NOMMU /* MMU only */
/* a->noexec is true */
rc = fork();
if (rc)
goto w;
/* child */
current_applet = a;
run_current_applet_and_exit(argc, argv);
#endif
}
}
rc = spawn(argv);
w:
return wait4pid(rc);
}
#if 0 //ndef BB_NOMMU
// Die with an error message if we can't daemonize.
void xdaemon(int nochdir, int noclose)
{
if (daemon(nochdir, noclose))
bb_perror_msg_and_die("daemon");
}
#endif
#if 0 // def BB_NOMMU
void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
{
int fd;
/* Maybe we are already re-execed and come here again? */
if (re_execed)
return;
setsid();
if (!nochdir)
- merge -r15463:15564 from busybox_scratch branch through these changesets: ------------------------------------------------------------------------ r15465 | aldot | 2006-06-21 20:48:06 +0200 (Wed, 21 Jun 2006) | 3 lines - use CONFIG_BUSYBOX_EXEC_PATH as before it one was broken by a recent revert. - use xchdir() since all is invain if it fails there anyways, supposedly ------------------------------------------------------------------------ r15466 | aldot | 2006-06-21 20:55:16 +0200 (Wed, 21 Jun 2006) | 2 lines - adjust docs to take CONFIG_BUSYBOX_EXEC_PATH into account. ------------------------------------------------------------------------ r15467 | aldot | 2006-06-21 21:31:24 +0200 (Wed, 21 Jun 2006) | 18 lines - partial fallout of my TREE_USED touchup against gcc-4.2: rip unused vars, save s 144 bytes text data bss dec hex filename 862434 10156 645924 1518514 172bb2 busybox.old 862322 10156 645892 1518370 172b22 busybox function old new delta z_len 4 - -4 textend 4 - -4 part_nb 4 - -4 insize 4 - -4 ifile_size 4 - -4 do_link 4 - -4 new_text 70 60 -10 ipaddr_list_link 33 23 -10 gzip_main 898 822 -76 ------------------------------------------------------------------------------ (add/remove: 0/6 grow/shrink: 0/3 up/down: 0/-120) Total: -120 bytes ------------------------------------------------------------------------ r15468 | aldot | 2006-06-21 21:43:05 +0200 (Wed, 21 Jun 2006) | 19 lines - remove useless global exports function old new delta rpm_main 940 1601 +661 rpm_getstring 107 112 +5 rpm_getint 148 153 +5 loop_through_files 103 106 +3 fileaction_dobackup 115 113 -2 fileaction_list 5 - -5 rpm_getcount 42 - -42 extract_cpio_gz 161 - -161 rpm_gettags 504 - -504 ------------------------------------------------------------------------------ (add/remove: 0/4 grow/shrink: 4/1 up/down: 674/-714) Total: -40 bytes text data bss dec hex filename 862322 10156 645892 1518370 172b22 busybox.old 862290 10156 645892 1518338 172b02 busybox ------------------------------------------------------------------------ r15555 | aldot | 2006-06-30 14:10:11 +0200 (Fri, 30 Jun 2006) | 22 lines - shrink syslog a little bit, move a big buffer (for 'line') off the bss, fold s emaphore stuff into single caller manually. stats: function old new delta logMessage 395 427 +32 message 1245 1257 +12 opts - 4 +4 small 1 - -1 local_logging 4 - -4 doRemoteLog 4 - -4 circular_logging 4 - -4 syslogd_main 1299 1285 -14 static.res 36 16 -20 .rodata 186650 186586 -64 static.line 1025 - -1025 ------------------------------------------------------------------------------ (add/remove: 1/5 grow/shrink: 2/3 up/down: 48/-1136) Total: -1088 bytes cow@s37:~/src/busybox_scratch$ size sysklogd/syslogd.o{.orig,} text data bss dec hex filename 3723 348 5242 9313 2461 sysklogd/syslogd.o.orig 3697 348 4188 8233 2029 sysklogd/syslogd.o ============================================================================== Overall bloatcheck for the changeset mentioned above: function old new delta rpm_main 953 1608 +655 logMessage 395 427 +32 message 1245 1257 +12 opts - 4 +4 rpm_getstring 107 110 +3 rpm_getint 148 151 +3 loop_through_files 103 104 +1 small 1 - -1 fileaction_dobackup 115 113 -2 z_len 4 - -4 textend 4 - -4 part_nb 4 - -4 local_logging 4 - -4 insize 4 - -4 ifile_size 4 - -4 do_link 4 - -4 doRemoteLog 4 - -4 circular_logging 4 - -4 fileaction_list 5 - -5 new_text 70 60 -10 ipaddr_list_link 33 23 -10 clear_bufs 31 21 -10 syslogd_main 1287 1273 -14 builtin_help 190 176 -14 static.res 36 16 -20 builtin_source 229 199 -30 rpm_getcount 42 - -42 gzip_main 842 786 -56 .rodata 227176 227112 -64 lash_main 609 527 -82 busy_loop 3883 3739 -144 extract_cpio_gz 155 - -155 rpm_gettags 501 - -501 static.line 1025 - -1025 ------------------------------------------------------------------------------ (add/remove: 1/15 grow/shrink: 6/12 up/down: 710/-2221) Total: -1511 bytes
2006-08-20 17:35:13 +00:00
xchdir("/");
if (!noclose) {
/* if "/dev/null" doesn't exist, bail out! */
fd = xopen(bb_dev_null, O_RDWR);
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
while (fd > 2)
close(fd--);
}
switch (vfork()) {
case 0: /* child */
/* Make certain we are not a session leader, or else we
* might reacquire a controlling terminal */
if (vfork())
_exit(0);
/* High-order bit of first char in argv[0] is a hidden
* "we have (alrealy) re-execed, don't do it again" flag */
argv[0][0] |= 0x80;
execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
case -1: /* error */
bb_perror_msg_and_die("vfork");
default: /* parent */
exit(0);
}
}
#endif /* BB_NOMMU */
#ifdef BB_NOMMU
void forkexit_or_rexec(char **argv)
{
pid_t pid;
/* Maybe we are already re-execed and come here again? */
if (re_execed)
return;
pid = vfork();
if (pid < 0) /* wtf? */
bb_perror_msg_and_die("vfork");
if (pid) /* parent */
exit(0);
/* child - re-exec ourself */
/* high-order bit of first char in argv[0] is a hidden
* "we have (alrealy) re-execed, don't do it again" flag */
argv[0][0] |= 0x80;
execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
}
#else
/* Dance around (void)...*/
#undef forkexit_or_rexec
void forkexit_or_rexec(void)
{
pid_t pid;
pid = fork();
if (pid < 0) /* wtf? */
bb_perror_msg_and_die("fork");
if (pid) /* parent */
exit(0);
/* child */
}
#define forkexit_or_rexec(argv) forkexit_or_rexec()
#endif
/* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
* char **argv "vanishes" */
void bb_daemonize_or_rexec(int flags, char **argv)
{
int fd;
fd = xopen(bb_dev_null, O_RDWR);
if (flags & DAEMON_CHDIR_ROOT)
xchdir("/");
if (flags & DAEMON_DEVNULL_STDIO) {
close(0);
close(1);
close(2);
}
while ((unsigned)fd < 2)
fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
if (!(flags & DAEMON_ONLY_SANITIZE)) {
forkexit_or_rexec(argv);
/* if daemonizing, make sure we detach from stdio */
setsid();
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
}
if (fd > 2)
close(fd--);
if (flags & DAEMON_CLOSE_EXTRA_FDS)
while (fd > 2)
close(fd--); /* close everything after fd#2 */
}
void bb_sanitize_stdio(void)
{
bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
}