Always prefer poll over select.
Even with the fd leak fixed, we were still calling this code with fds
greater than 1024. From a tombstone from a dumpstate crash:
open files:
fd 0: /dev/pts/0
...
fd 18: /dev/stune/rt/tasks
fd 1806: /data/anr/anr_2018-03-15-15-39-43-990
fd 1807: /data/anr/anr_2018-03-15-15-39-43-991
fd 1808: /data/anr/anr_2018-03-15-15-39-43-992
fd 1809: /data/anr/anr_2018-03-15-15-39-43-993
fd 1810: /data/anr/anr_2018-03-15-15-39-43-994
fd 1811: /data/anr/anr_2018-03-15-15-39-43-995
fd 1812: /data/anr/anr_2018-03-15-15-39-43-996
fd 1813: /data/anr/anr_2018-03-15-15-39-43-997
fd 1814: /data/anr/anr_2018-03-15-15-39-43-998
fd 1815: /data/anr/anr_2018-03-15-15-39-43-999
Bug: http://b/73140330
Test: filled /data/anr/ with 2000 fake anrs, ran `dumpstate`
Change-Id: Ifa249050139e3683064a620f05d3f5ca645a739f
diff --git a/cmds/dumpstate/DumpstateInternal.cpp b/cmds/dumpstate/DumpstateInternal.cpp
index 819d5b9..33e35f7 100644
--- a/cmds/dumpstate/DumpstateInternal.cpp
+++ b/cmds/dumpstate/DumpstateInternal.cpp
@@ -20,6 +20,7 @@
#include <errno.h>
#include <grp.h>
+#include <poll.h>
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
@@ -35,6 +36,7 @@
#include <vector>
#include <android-base/file.h>
+#include <android-base/macros.h>
#include <log/log.h>
uint64_t Nanotime() {
@@ -154,22 +156,16 @@
return 0;
}
bool newline = false;
- fd_set read_set;
- timeval tm;
while (true) {
- FD_ZERO(&read_set);
- FD_SET(fd, &read_set);
- /* Timeout if no data is read for 30 seconds. */
- tm.tv_sec = 30;
- tm.tv_usec = 0;
- uint64_t elapsed = Nanotime();
- int ret = TEMP_FAILURE_RETRY(select(fd + 1, &read_set, nullptr, nullptr, &tm));
+ uint64_t start_time = Nanotime();
+ pollfd fds[] = { { .fd = fd, .events = POLLIN } };
+ int ret = TEMP_FAILURE_RETRY(poll(fds, arraysize(fds), 30 * 1000));
if (ret == -1) {
- dprintf(out_fd, "*** %s: select failed: %s\n", path, strerror(errno));
+ dprintf(out_fd, "*** %s: poll failed: %s\n", path, strerror(errno));
newline = true;
break;
} else if (ret == 0) {
- elapsed = Nanotime() - elapsed;
+ uint64_t elapsed = Nanotime() - start_time;
dprintf(out_fd, "*** %s: Timed out after %.3fs\n", path, (float)elapsed / NANOS_PER_SEC);
newline = true;
break;
