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authorDenis Vlasenko2007-03-26 13:20:04 +0000
committerDenis Vlasenko2007-03-26 13:20:04 +0000
commitbb7fcb4229fd5ff583039f26ca1c06340e3f09ea (patch)
tree5e4a6cc92e42ff7694ffc8b6a91434640e953726 /libbb/vfork_daemon_rexec.c
parentf62c6fa1cae0f944243c57b0a776c29eb0c61f18 (diff)
downloadbusybox-bb7fcb4229fd5ff583039f26ca1c06340e3f09ea.zip
busybox-bb7fcb4229fd5ff583039f26ca1c06340e3f09ea.tar.gz
libbb: rework NOMMU helper API so that it makes more sense
and easier to use. Doesn't compile - need two more commits.
Diffstat (limited to 'libbb/vfork_daemon_rexec.c')
-rw-r--r--libbb/vfork_daemon_rexec.c134
1 files changed, 133 insertions, 1 deletions
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 3185f2d..c59b0b6 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -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);
+}