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Use read(2) instead of fgets(3) when reading process output.

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This patch modifies `tor_read_all_handle()` to use read(2) instead of
fgets(3) when reading the stdout from the child process. This should
eliminate the race condition that can be triggered in the 'slow/util/*'
tests on slower machines running OpenBSD, FreeBSD and HardenedBSD.

See: https://bugs.torproject.org/21654
This commit is contained in:
Alexander Færøy 2017-03-08 00:12:06 +01:00 committed by Alexander Færøy
parent ad19f1507a
commit 86de065aee
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GPG Key ID: E15081D5D3C3DB53
1 changed files with 18 additions and 24 deletions
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42
src/common/util.c
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@ -5010,7 +5010,7 @@ tor_read_all_handle(FILE *h, char *buf, size_t count,
int *eof)
{
size_t numread = 0;
char *retval;
ssize_t result;
if (eof)
*eof = 0;
@ -5019,33 +5019,27 @@ tor_read_all_handle(FILE *h, char *buf, size_t count,
return -1;
while (numread != count) {
/* Use fgets because that is what we use in log_from_pipe() */
retval = tor_fgets(buf+numread, (int)(count-numread), h);
if (NULL == retval) {
if (feof(h)) {
log_debug(LD_GENERAL, "fgets() reached end of file");
if (eof)
*eof = 1;
result = read(fileno(h), buf+numread, count-numread);
if (result == 0) {
log_debug(LD_GENERAL, "read() reached end of file");
if (eof)
*eof = 1;
break;
} else if (result < 0 && errno == EAGAIN) {
if (process)
continue;
else
break;
} else {
if (EAGAIN == errno) {
if (process)
continue;
else
break;
} else {
log_warn(LD_GENERAL, "fgets() from handle failed: %s",
strerror(errno));
return -1;
}
}
} else if (result < 0) {
log_warn(LD_GENERAL, "read() failed: %s", strerror(errno));
return -1;
}
tor_assert(retval != NULL);
tor_assert(strlen(retval) + numread <= count);
numread += strlen(retval);
numread += result;
}
log_debug(LD_GENERAL, "fgets() read %d bytes from handle", (int)numread);
log_debug(LD_GENERAL, "read() read %d bytes from handle", (int)numread);
return (ssize_t)numread;
}
#endif