Add pthread_getname_np.
Also guard both these GNU extensions with _GNU_SOURCE.
Also improve the tests to test each case on both the current thread and
another thread, since the code paths are totally different.
Bug: http://b/27810459
Change-Id: I72b05bca5c5b6ca8ba4585b8edfb716a1c252f92
diff --git a/libc/bionic/pthread_setname_np.cpp b/libc/bionic/pthread_setname_np.cpp
index bb1114e..6d2880e 100644
--- a/libc/bionic/pthread_setname_np.cpp
+++ b/libc/bionic/pthread_setname_np.cpp
@@ -41,41 +41,69 @@
// This value is not exported by kernel headers.
#define MAX_TASK_COMM_LEN 16
-#define TASK_COMM_FMT "/proc/self/task/%d/comm"
+
+static int __open_task_comm_fd(pthread_t t, int flags) {
+ pthread_internal_t* thread = __pthread_internal_find(t);
+ if (thread == nullptr) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ char comm_name[64];
+ snprintf(comm_name, sizeof(comm_name), "/proc/self/task/%d/comm", thread->tid);
+ return open(comm_name, O_CLOEXEC | flags);
+}
+
+int pthread_getname_np(pthread_t t, char* buf, size_t buf_size) {
+ ErrnoRestorer errno_restorer;
+
+ if (buf_size < MAX_TASK_COMM_LEN) return ERANGE;
+
+ // Getting our own name is an easy special case.
+ if (t == pthread_self()) {
+ return prctl(PR_GET_NAME, buf) ? errno : 0;
+ }
+
+ // We have to get another thread's name.
+ int fd = __open_task_comm_fd(t, O_RDONLY);
+ if (fd == -1) return errno;
+
+ ssize_t n = TEMP_FAILURE_RETRY(read(fd, buf, buf_size));
+ close(fd);
+
+ if (n == -1) return errno;
+
+ // The kernel adds a trailing '\n' to the /proc file,
+ // so this is actually the normal case for short names.
+ if (n > 0 && buf[n - 1] == '\n') {
+ buf[n - 1] = '\0';
+ return 0;
+ }
+
+ if (n == static_cast<ssize_t>(buf_size)) return ERANGE;
+ buf[n] = '\0';
+ return 0;
+}
int pthread_setname_np(pthread_t t, const char* thread_name) {
ErrnoRestorer errno_restorer;
size_t thread_name_len = strlen(thread_name);
- if (thread_name_len >= MAX_TASK_COMM_LEN) {
- return ERANGE;
- }
+ if (thread_name_len >= MAX_TASK_COMM_LEN) return ERANGE;
- // Changing our own name is an easy special case.
+ // Setting our own name is an easy special case.
if (t == pthread_self()) {
return prctl(PR_SET_NAME, thread_name) ? errno : 0;
}
- // We have to change another thread's name.
- pthread_internal_t* thread = __pthread_internal_find(t);
- if (thread == NULL) {
- return ENOENT;
- }
- pid_t tid = thread->tid;
+ // We have to set another thread's name.
+ int fd = __open_task_comm_fd(t, O_WRONLY);
+ if (fd == -1) return errno;
- char comm_name[sizeof(TASK_COMM_FMT) + 8];
- snprintf(comm_name, sizeof(comm_name), TASK_COMM_FMT, tid);
- int fd = open(comm_name, O_CLOEXEC | O_WRONLY);
- if (fd == -1) {
- return errno;
- }
ssize_t n = TEMP_FAILURE_RETRY(write(fd, thread_name, thread_name_len));
close(fd);
- if (n < 0) {
- return errno;
- } else if (n != static_cast<ssize_t>(thread_name_len)) {
- return EIO;
- }
+ if (n == -1) return errno;
+ if (n != static_cast<ssize_t>(thread_name_len)) return EIO;
return 0;
}