diff options
authorRich Felker <>2020-08-17 20:12:53 -0400
committerRich Felker <>2020-08-17 20:12:53 -0400
commitd49cf07541bb54a5ac7aec1feec8514db33db8ea (patch)
parent22359b54ab9a3ff0a854490f3eb0fcb838e785af (diff)
add gettid function
this is a prerequisite for addition of other interfaces that use kernel tids, including futex and SIGEV_THREAD_ID. there is some ambiguity as to whether the semantic return type should be int or pid_t. either way, futex API imposes a contract that the values fit in int (excluding some upper reserved bits). glibc used pid_t, so in the interest of not having gratuitous mismatch (the underlying types are the same anyway), pid_t is used here as well. while conceptually this is a syscall, the copy stored in the thread structure is always valid in all contexts where it's valid to call libc functions, so it's used to avoid the syscall.
2 files changed, 9 insertions, 0 deletions
diff --git a/include/unistd.h b/include/unistd.h
index 7bcbff94..07584a23 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -190,6 +190,7 @@ int syncfs(int);
int euidaccess(const char *, int);
int eaccess(const char *, int);
ssize_t copy_file_range(int, off_t *, int, off_t *, size_t, unsigned);
+pid_t gettid(void);
#if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
diff --git a/src/linux/gettid.c b/src/linux/gettid.c
new file mode 100644
index 00000000..70767137
--- /dev/null
+++ b/src/linux/gettid.c
@@ -0,0 +1,8 @@
+#define _GNU_SOURCE
+#include <unistd.h>
+#include "pthread_impl.h"
+pid_t gettid(void)
+ return __pthread_self()->tid;