gugelfrei
/
android_system_vold
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Ensure vold doesn't hang when a child process dies

Browse Source 
Add a monitoring thread that notifies the main parent thread when the child
process terminates. The return code from the child is then propagated back up
to the parent.

Change-Id: Idf46e100e8dee2e8f1aaa331317f3c4955632183
gugelfrei
Rom Lemarchand 12 years ago
parent e90c1749b0
commit b9dcde7845
1 changed files with 113 additions and 46 deletions
Show Stats Download Patch File Download Diff File

159
logwrapper.c
Unescape View File

@ -15,6 +15,8 @@
*/
#include <string.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
@ -22,75 +24,93 @@
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include "private/android_filesystem_config.h"
#include "cutils/log.h"
#include "cutils/sched_policy.h"
int parent(const char *tag, int parent_read) {
struct monitor_data {
const char *tag;
int fd;
};
static int parent(const char *tag, int parent_read, int monitor_read) {
int status;
char buffer[4096];
fd_set fds;
int maxfd;
int rc = -EAGAIN;
int a = 0; // start index of unprocessed data
int b = 0; // end index of unprocessed data
int sz;
while ((sz = read(parent_read, &buffer[b], sizeof(buffer) - 1 - b)) > 0) {
sz += b;
// Log one line at a time
for (b = 0; b < sz; b++) {
if (buffer[b] == '\r') {
buffer[b] = '\0';
} else if (buffer[b] == '\n') {
buffer[b] = '\0';
maxfd = 1 + (parent_read > monitor_read ? parent_read : monitor_read);
do {
FD_ZERO(&fds);
FD_SET(parent_read, &fds);
FD_SET(monitor_read, &fds);
if (select(maxfd, &fds, NULL, NULL, NULL) <= 0) {
ALOG(LOG_INFO, "logwrapper", "select failed");
break;
}
if (FD_ISSET(parent_read, &fds)) {
sz = read(parent_read, &buffer[b], sizeof(buffer) - 1 - b);
sz += b;
// Log one line at a time
for (b = 0; b < sz; b++) {
if (buffer[b] == '\r') {
buffer[b] = '\0';
} else if (buffer[b] == '\n') {
buffer[b] = '\0';
ALOG(LOG_INFO, tag, "%s", &buffer[a]);
a = b + 1;
}
}
if (a == 0 && b == sizeof(buffer) - 1) {
// buffer is full, flush
buffer[b] = '\0';
ALOG(LOG_INFO, tag, "%s", &buffer[a]);
a = b + 1;
b = 0;
} else if (a != b) {
// Keep left-overs
b -= a;
memmove(buffer, &buffer[a], b);
a = 0;
} else {
a = 0;
b = 0;
}
}
if (a == 0 && b == sizeof(buffer) - 1) {
// buffer is full, flush
buffer[b] = '\0';
ALOG(LOG_INFO, tag, "%s", &buffer[a]);
b = 0;
} else if (a != b) {
// Keep left-overs
b -= a;
memmove(buffer, &buffer[a], b);
a = 0;
} else {
a = 0;
b = 0;
// Child exited, get return status and exit loop
if (FD_ISSET(monitor_read, &fds)) {
if (read(monitor_read, &rc, sizeof(rc)) != sizeof(rc)) {
ALOG(LOG_ERROR, "logwrapper", "Unable to read child return "
"status");
rc = -ECHILD;
}
break;
}
} while (1);
}
// Flush remaining data
if (a != b) {
buffer[b] = '\0';
ALOG(LOG_INFO, tag, "%s", &buffer[a]);
}
status = 0xAAAA;
if (wait(&status) != -1) { // Wait for child
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != 0) {
ALOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)", tag,
WEXITSTATUS(status));
}
return WEXITSTATUS(status);
} else if (WIFSIGNALED(status))
ALOG(LOG_INFO, "logwrapper", "%s terminated by signal %d", tag,
WTERMSIG(status));
else if (WIFSTOPPED(status))
ALOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", tag,
WSTOPSIG(status));
} else
ALOG(LOG_INFO, "logwrapper", "%s wait() failed: %s (%d)", tag,
strerror(errno), errno);
return -EAGAIN;
return rc;
}
void child(int argc, const char**argv) {
static void child(int argc, const char**argv) {
// create null terminated argv_child array
char* argv_child[argc + 1];
memcpy(argv_child, argv, argc * sizeof(char *));
@ -104,6 +124,33 @@ void child(int argc, const char**argv) {
}
}
static void *monitor(void *arg)
{
struct monitor_data *data = arg;
int status;
int rc = -EAGAIN;
if (wait(&status) != -1) { // Wait for child
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != 0) {
ALOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)",
data->tag, WEXITSTATUS(status));
}
rc = WEXITSTATUS(status);
} else if (WIFSIGNALED(status))
ALOG(LOG_INFO, "logwrapper", "%s terminated by signal %d",
data->tag, WTERMSIG(status));
else if (WIFSTOPPED(status))
ALOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", data->tag,
WSTOPSIG(status));
} else
ALOG(LOG_INFO, "logwrapper", "%s wait() failed: %s (%d)", data->tag,
strerror(errno), errno);
write(data->fd, &rc, sizeof(rc));
return NULL;
}
int logwrap(int argc, const char* argv[], int background)
{
pid_t pid;
@ -135,15 +182,14 @@ int logwrap(int argc, const char* argv[], int background)
/*
* Child
*/
close(parent_ptty);
child_ptty = open(child_devname, O_RDWR);
if (child_ptty < 0) {
close(parent_ptty);
ALOG(LOG_ERROR, "logwrapper", "Problem with child ptty");
_exit(-errno);
}
// redirect stdout and stderr
close(parent_ptty);
dup2(child_ptty, 1);
dup2(child_ptty, 2);
close(child_ptty);
@ -161,8 +207,29 @@ int logwrap(int argc, const char* argv[], int background)
/*
* Parent
*/
int rc = parent(argv[0], parent_ptty);
int rc, err;
int sockets[2];
pthread_t thread_id;
struct monitor_data data;
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets)) {
err = errno;
ALOG(LOG_ERROR, "logwrapper", "Unable to create monitoring "
"socket: %s (%d)", strerror(err), err);
exit(-err);
}
data.tag = argv[0];
data.fd = sockets[1];
err = pthread_create(&thread_id, NULL, monitor, &data);
if (err != 0) {
ALOG(LOG_ERROR, "logwrapper", "Unable to create monitoring "
"thread: %s (%d)", strerror(err), err);
exit(-err);
}
rc = parent(argv[0], parent_ptty, sockets[0]);
close(parent_ptty);
close(sockets[0]);
close(sockets[1]);
return rc;
}

Write Preview
Loading…
Cancel
Save