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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_read.c
View file

@ -15,9 +15,13 @@ size_t __stdio_read(FILE *f, unsigned char *buf, size_t len)
}; };
ssize_t cnt; ssize_t cnt;
pthread_cleanup_push(cleanup, f); if (libc.main_thread) {
cnt = syscall_cp(SYS_readv, f->fd, iov, 2); pthread_cleanup_push(cleanup, f);
pthread_cleanup_pop(0); cnt = syscall_cp(SYS_readv, f->fd, iov, 2);
pthread_cleanup_pop(0);
} else {
cnt = syscall(SYS_readv, f->fd, iov, 2);
}
if (cnt <= 0) { if (cnt <= 0) {
f->flags |= F_EOF ^ ((F_ERR^F_EOF) & cnt); f->flags |= F_EOF ^ ((F_ERR^F_EOF) & cnt);
f->rpos = f->rend = 0; f->rpos = f->rend = 0;

10
src/stdio/__stdio_write.c
View file

@ -18,9 +18,13 @@ size_t __stdio_write(FILE *f, const unsigned char *buf, size_t len)
int iovcnt = 2; int iovcnt = 2;
ssize_t cnt; ssize_t cnt;
for (;;) { for (;;) {
pthread_cleanup_push(cleanup, f); if (libc.main_thread) {
cnt = syscall_cp(SYS_writev, f->fd, iov, iovcnt); pthread_cleanup_push(cleanup, f);
pthread_cleanup_pop(0); 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) { if (cnt == rem) {
f->wend = f->buf + f->buf_size; f->wend = f->buf + f->buf_size;
f->wpos = f->wbase = f->buf; f->wpos = f->wbase = f->buf;