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libbb: rework NOMMU helper API so that it makes more sense

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and easier to use. Doesn't compile - need two more commits.
This commit is contained in:
Denis Vlasenko
2007-03-26 13:20:04 +00:00
parent f62c6fa1ca
commit bb7fcb4229
3 changed files with 191 additions and 107 deletions
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134
libbb/vfork_daemon_rexec.c
View File

@ -18,11 +18,68 @@
#include <paths.h>
#include "libbb.h"
#ifdef BB_NOMMU
/* 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;
// Be nice to nommu machines.
failed = 0;
pid = vfork();
if (pid < 0) /* error */
return pid;
if (!pid) { /* child */
/* Don't use BB_EXECVP tricks here! */
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(0);
}
/* parent */
/* Unfortunately, this is not reliable: vfork()
* can be equivalent to fork() according to standards */
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;
}
#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)
@ -56,3 +113,78 @@ void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
}
}
#endif /* BB_NOMMU */
#ifdef BB_NOMMU
static void daemon_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
static void daemon_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 daemon_or_rexec(argv) daemon_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)) {
daemon_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);
}

78
libbb/xfuncs.c
View File

@ -187,43 +187,6 @@ void xfflush_stdout(void)
}
}
// This does a fork/exec in one call, using vfork(). Return PID of new child,
// -1 for failure. Runs argv[0], searching path if that has no / in it.
pid_t spawn(char **argv)
{
/* Why static? */
static int failed;
pid_t pid;
// Be nice to nommu machines.
failed = 0;
pid = vfork();
if (pid < 0) return pid;
if (!pid) {
BB_EXECVP(argv[0], argv);
// We're 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(0);
}
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)
{
@ -510,47 +473,6 @@ DIR *xopendir(const char *path)
return dp;
}
#ifndef 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
void bb_sanitize_stdio_maybe_daemonize(int daemonize)
{
int fd;
/* Mega-paranoid */
fd = xopen(bb_dev_null, O_RDWR);
while ((unsigned)fd < 2)
fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
if (daemonize) {
pid_t pid = fork();
if (pid < 0) /* wtf? */
bb_perror_msg_and_die("fork");
if (pid) /* parent */
exit(0);
/* child */
/* if daemonizing, make sure we detach from stdio */
setsid();
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
}
while (fd > 2)
close(fd--); /* close everything after fd#2 */
}
void bb_sanitize_stdio(void)
{
bb_sanitize_stdio_maybe_daemonize(0);
}
void bb_daemonize(void)
{
bb_sanitize_stdio_maybe_daemonize(1);
}
// Die with an error message if we can't open a new socket.
int xsocket(int domain, int type, int protocol)
{