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avoid using pthread cleanup push/pop in stdio when not needed

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unfortunately in dynamic-linked programs, these macros cause
pthread_self to be initialized, which costs a couple syscalls, and
(much worse) would necessarily fail, crash, and burn on ancient (2.4
and earlier) kernels where setting up a thread pointer does not work.

i'd like to do this in a more generic way that avoids all use of
cleanup push/pop before pthread_self has been successfully called and
avoids ugly if/else constructs like the one in this commit, but for
now, this will suffice.
This commit is contained in:
Rich Felker 2012-05-25 22:44:34 -04:00
commit 3f25354e62
2 changed files with 14 additions and 6 deletions
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10
src/stdio/__stdio_write.c
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@ -18,9 +18,13 @@ size_t __stdio_write(FILE *f, const unsigned char *buf, size_t len)
int iovcnt = 2;
ssize_t cnt;
for (;;) {
pthread_cleanup_push(cleanup, f);
cnt = syscall_cp(SYS_writev, f->fd, iov, iovcnt);
pthread_cleanup_pop(0);
if (libc.main_thread) {
pthread_cleanup_push(cleanup, f);
cnt = syscall_cp(SYS_writev, f->fd, iov, iovcnt);
pthread_cleanup_pop(0);
} else {
cnt = syscall(SYS_writev, f->fd, iov, iovcnt);
}
if (cnt == rem) {
f->wend = f->buf + f->buf_size;
f->wpos = f->wbase = f->buf;