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platform_system_core
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logwrap: ensure child exits with _exit 

Always exit the child process with _exit() rather than exit() to ensure none
of the parent's atexit functions get called if the child needs to exit before
calling exec.

Change-Id: I6a75111ef1bb3468c114c98743565471cf82c9dd
This commit is contained in:
Rom Lemarchand 2013-01-07 15:50:02 -08:00
parent 83dee8e4e5
commit 99e1966400
1 changed files with 19 additions and 20 deletions
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39
logwrapper/logwrap.c
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@ -36,10 +36,17 @@
static int signal_fd_write;
static void fatal(const char *msg) {
fprintf(stderr, "%s", msg);
ALOG(LOG_ERROR, "logwrapper", "%s", msg);
}
#define ERROR(fmt, args...) \
do { \
fprintf(stderr, fmt, ## args); \
ALOG(LOG_ERROR, "logwrapper", fmt, ## args); \
} while(0)
#define FATAL_CHILD(fmt, args...) \
do { \
ERROR(fmt, ## args); \
_exit(-1); \
} while(0)
static int parent(const char *tag, int parent_read, int signal_fd, pid_t pid,
int *chld_sts) {
@ -75,7 +82,7 @@ static int parent(const char *tag, int parent_read, int signal_fd, pid_t pid,
if (poll(poll_fds, remote_hung ? 1 : 2, -1) < 0) {
if (errno == EINTR)
continue;
fatal("poll failed\n");
ERROR("poll failed\n");
rc = -1;
goto err_poll;
}
@ -166,9 +173,8 @@ static void child(int argc, char* argv[]) {
argv_child[argc] = NULL;
if (execvp(argv_child[0], argv_child)) {
ALOG(LOG_ERROR, "logwrapper",
"executing %s failed: %s\n", argv_child[0], strerror(errno));
exit(-1);
FATAL_CHILD("executing %s failed: %s\n", argv_child[0],
strerror(errno));
}
}
@ -191,14 +197,14 @@ int logwrap(int argc, char* argv[], int *status) {
/* Use ptty instead of socketpair so that STDOUT is not buffered */
parent_ptty = open("/dev/ptmx", O_RDWR);
if (parent_ptty < 0) {
fatal("Cannot create parent ptty\n");
ERROR("Cannot create parent ptty\n");
rc = -1;
goto err_open;
}
if (grantpt(parent_ptty) || unlockpt(parent_ptty) ||
((child_devname = (char*)ptsname(parent_ptty)) == 0)) {
fatal("Problem with /dev/ptmx\n");
ERROR("Problem with /dev/ptmx\n");
rc = -1;
goto err_ptty;
}
@ -209,7 +215,7 @@ int logwrap(int argc, char* argv[], int *status) {
pid = fork();
if (pid < 0) {
fatal("Failed to fork\n");
ERROR("Failed to fork\n");
rc = -1;
goto err_fork;
} else if (pid == 0) {
@ -218,8 +224,7 @@ int logwrap(int argc, char* argv[], int *status) {
child_ptty = open(child_devname, O_RDWR);
if (child_ptty < 0) {
fatal("Problem with child ptty\n");
return -1;
FATAL_CHILD("Problem with child ptty\n");
}
// redirect stdout and stderr
@ -228,8 +233,6 @@ int logwrap(int argc, char* argv[], int *status) {
close(child_ptty);
child(argc, argv);
fatal("This should never happen\n");
return -1;
} else {
memset(&chldact, 0, sizeof(chldact));
chldact.sa_handler = sigchld_handler;
@ -247,11 +250,7 @@ int logwrap(int argc, char* argv[], int *status) {
rc = socketpair(AF_UNIX, SOCK_STREAM, 0, sockets);
if (rc == -1) {
char msg[40];
snprintf(msg, sizeof(msg), "socketpair failed: %d\n", errno);
fatal(msg);
ERROR("socketpair failed: %s\n", strerror(errno));
goto err_socketpair;
}