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unix: work around darwin bug, don't poll() on pipe

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poll() on newer versions of OS X sets POLLHUP|POLLIN whereas older versions
(and other Unices) only set POLLHUP. It was tripping up a check that expected
to read data when POLLIN was set.

While easy to work around, I switched it to a blocking read instead:
it's less code and avoids surprises like the one above altogether.

Fixes #522.
This commit is contained in:
Ben Noordhuis 2012-08-12 00:37:26 +02:00
parent 23dc564f3b
commit ac0d46851a
1 changed files with 13 additions and 29 deletions
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42
src/unix/process.c
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@ -249,19 +249,6 @@ static void uv__process_close_stream(uv_stdio_container_t* container) {
}
static int uv__read_int(int fd) {
ssize_t n;
int val;
do
n = read(fd, &val, sizeof(val));
while (n == -1 && errno == EINTR);
assert(n == sizeof(val));
return val;
}
static void uv__write_int(int fd, int val) {
ssize_t n;
@ -347,13 +334,12 @@ int uv_spawn(uv_loop_t* loop,
uv_process_t* process,
const uv_process_options_t options) {
int signal_pipe[2] = { -1, -1 };
struct pollfd pfd;
int (*pipes)[2];
int stdio_count;
ngx_queue_t* q;
ssize_t r;
pid_t pid;
int i;
int r;
assert(options.file != NULL);
assert(!(options.flags & ~(UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS |
@ -409,9 +395,9 @@ int uv_spawn(uv_loop_t* loop,
*
* To avoid ambiguity, we create a pipe with both ends
* marked close-on-exec. Then, after the call to `fork()`,
* the parent polls the read end until it sees POLLHUP.
* the parent polls the read end until it EOFs or errors with EPIPE.
*/
if (uv__make_pipe(signal_pipe, UV__F_NONBLOCK))
if (uv__make_pipe(signal_pipe, 0))
goto error;
pid = fork();
@ -427,23 +413,21 @@ int uv_spawn(uv_loop_t* loop,
abort();
}
/* POLLHUP signals child has exited or execve()'d. */
close(signal_pipe[1]);
pfd.revents = 0;
pfd.events = POLLIN|POLLHUP;
pfd.fd = signal_pipe[0];
process->errorno = 0;
do
r = poll(&pfd, 1, -1);
r = read(signal_pipe[0], &process->errorno, sizeof(process->errorno));
while (r == -1 && errno == EINTR);
assert((r == 1) && "poll()_on read end of pipe failed");
assert((pfd.revents & (POLLIN|POLLHUP)) && "unexpected poll() revents");
if (pfd.revents & POLLIN)
process->errorno = uv__read_int(signal_pipe[0]);
else /* POLLHUP */
process->errorno = 0;
if (r == 0)
; /* okay, EOF */
else if (r == sizeof(process->errorno))
; /* okay, read errorno */
else if (r == -1 && errno == EPIPE)
; /* okay, got EPIPE */
else
abort();
close(signal_pipe[0]);