fix race opening the uvar pipe

Fixes #3426
This commit is contained in:
Kurtis Rader 2016-12-20 22:04:00 -08:00
parent 1f2432d63a
commit 8ba2a4cfd4

View file

@ -1193,36 +1193,7 @@ class universal_notifier_named_pipe_t : public universal_notifier_t {
bool polling_due_to_readable_fd; bool polling_due_to_readable_fd;
long long drain_if_still_readable_time_usec; long long drain_if_still_readable_time_usec;
void make_pipe(const wchar_t *test_path) { void make_pipe(const wchar_t *test_path);
wcstring vars_path = test_path ? wcstring(test_path) : default_named_pipe_path();
vars_path.append(L".notifier");
const std::string narrow_path = wcs2string(vars_path);
int fd = wopen_cloexec(vars_path, O_RDWR | O_NONBLOCK, 0600);
if (fd < 0 && errno == ENOENT) {
// File doesn't exist, try creating it.
int mkfifo_status = mkfifo(narrow_path.c_str(), 0600);
if (mkfifo_status != -1) {
fd = wopen_cloexec(vars_path, O_RDWR | O_NONBLOCK, 0600);
}
}
if (fd < 0) {
// Maybe open failed, maybe mkfifo failed.
// We explicitly do NOT report an error for ENOENT or EACCESS. This works around #1955,
// where $XDG_RUNTIME_DIR may get a bogus value under success.
if (errno != ENOENT && errno != EPERM) {
const char *error = strerror(errno);
debug(
0,
_(L"Unable to make or open a FIFO for universal variables with path '%ls': %s"),
vars_path.c_str(), error);
}
pipe_fd = -1;
} else {
pipe_fd = fd;
}
}
void drain_excessive_data() { void drain_excessive_data() {
// The pipe seems to have data on it, that won't go away. Read a big chunk out of it. We // The pipe seems to have data on it, that won't go away. Read a big chunk out of it. We
@ -1467,3 +1438,29 @@ bool universal_notifier_t::notification_fd_became_readable(int fd) {
UNUSED(fd); UNUSED(fd);
return false; return false;
} }
void universal_notifier_named_pipe_t::make_pipe(const wchar_t *test_path) {
wcstring vars_path = test_path ? wcstring(test_path) : default_named_pipe_path();
vars_path.append(L".notifier");
const std::string narrow_path = wcs2string(vars_path);
int mkfifo_status = mkfifo(narrow_path.c_str(), 0600);
if (mkfifo_status == -1 && errno != EEXIST) {
const char *error = strerror(errno);
const wchar_t *errmsg = _(L"Unable to make a pipe for universal variables using '%ls': %s");
debug(0, errmsg, vars_path.c_str(), error);
pipe_fd = -1;
return;
}
int fd = wopen_cloexec(vars_path, O_RDWR | O_NONBLOCK, 0600);
if (fd < 0) {
const char *error = strerror(errno);
const wchar_t *errmsg = _(L"Unable to open a pipe for universal variables using '%ls': %s");
debug(0, errmsg, vars_path.c_str(), error);
pipe_fd = -1;
return;
}
pipe_fd = fd;
}