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conmon: Handle EINTR and partial writes when writing

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Any write could be interupted by EINTR if we get some kind of signal,
which means we could be either reporting a EINTR error or a partial
write (if some data was written). Its also generally good to handle
partial writes correctly, as they can happen e.g. when writing to
full pipes.

Signed-off-by: Alexander Larsson <alexl@redhat.com>
This commit is contained in:
Alexander Larsson 2017-06-02 11:52:33 +02:00
parent b5153e08c5
commit ae933d0d03
1 changed files with 28 additions and 7 deletions
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35
conmon/conmon.c
View file

@ -109,6 +109,27 @@ static GOptionEntry entries[] =
#define CGROUP_ROOT "/sys/fs/cgroup"
static ssize_t write_all(int fd, const void *buf, size_t count)
{
size_t remaining = count;
const char *p = buf;
ssize_t res;
while (remaining > 0) {
do {
res = write(fd, p, remaining);
} while (res == -1 && errno == EINTR);
if (res <= 0)
return -1;
remaining -= res;
p += res;
}
return count;
}
int set_k8s_timestamp(char *buf, ssize_t buflen)
{
struct tm *tm;
@ -221,7 +242,7 @@ int write_k8s_log(int fd, stdpipe_t pipe, const char *buf, ssize_t buflen)
}
/* Output the actual contents. */
if (write(fd, buf, line_len) < 0) {
if (write_all(fd, buf, line_len) < 0) {
nwarn("failed to write buffer to log");
goto next;
}
@ -559,7 +580,7 @@ int main(int argc, char *argv[])
* We send -1 as pid to signal to parent that create container has failed.
*/
len = snprintf(buf, BUF_SIZE, "{\"pid\": %d}\n", -1);
if (len < 0 || write(sync_pipe_fd, buf, len) != len) {
if (len < 0 || write_all(sync_pipe_fd, buf, len) != len) {
pexit("unable to send container pid to parent");
}
} else {
@ -588,7 +609,7 @@ int main(int argc, char *argv[])
g_object_set(generator, "pretty", FALSE, NULL);
data = json_generator_to_data (generator, &len);
fprintf(stderr, "%s\n", data);
if (write(sync_pipe_fd, data, len) != (int)len) {
if (write_all(sync_pipe_fd, data, len) != (int)len) {
ninfo("Unable to send container stderr message to parent");
}
@ -615,7 +636,7 @@ int main(int argc, char *argv[])
/* Send the container pid back to parent */
if (sync_pipe_fd > 0 && !exec) {
len = snprintf(buf, BUF_SIZE, "{\"pid\": %d}\n", cpid);
if (len < 0 || write(sync_pipe_fd, buf, len) != len) {
if (len < 0 || write_all(sync_pipe_fd, buf, len) != len) {
pexit("unable to send container pid to parent");
}
}
@ -643,7 +664,7 @@ int main(int argc, char *argv[])
pexit("Failed to create eventfd");
wb = snprintf(buf, BUF_SIZE, "%d %d", efd, ofd);
if (write(cfd, buf, wb) < 0)
if (write_all(cfd, buf, wb) < 0)
pexit("Failed to write to cgroup.event_control");
}
@ -749,7 +770,7 @@ out:
/* Send the command exec exit code back to the parent */
if (sync_pipe_fd > 0) {
len = snprintf(buf, BUF_SIZE, "{\"exit_code\": %d}\n", exit_status);
if (len < 0 || write(sync_pipe_fd, buf, len) != len) {
if (len < 0 || write_all(sync_pipe_fd, buf, len) != len) {
pexit("unable to send exit status");
exit(1);
}
@ -767,7 +788,7 @@ out:
* to the parent.
*/
len = snprintf(buf, BUF_SIZE, "{\"exit_code\": %d}\n", WEXITSTATUS(runtime_status));
if (len < 0 || write(sync_pipe_fd, buf, len) != len) {
if (len < 0 || write_all(sync_pipe_fd, buf, len) != len) {
pexit("unable to send exit status");
exit(1);
}