cosmopolitan/libc/calls/readlinkat.c
Justine Tunney d5910e2673
Fix bugs and make code tinier
- Fixed bug where stdio eof wasn't being sticky
- Fixed bug where fseeko() wasn't clearing eof state
- Removed assert() usage from libc favoring _unassert() / _npassert()
2022-10-09 23:21:34 -07:00

61 lines
3.4 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/errfuns.h"
#include "libc/zipos/zipos.internal.h"
/**
* Reads symbolic link.
*
* This does *not* nul-terminate the buffer.
*
* @param dirfd is normally AT_FDCWD but if it's an open directory and
* file is a relative path, then file is opened relative to dirfd
* @param path must be a symbolic link pathname
* @param buf will receive symbolic link contents, and won't be modified
* unless the function succeeds (with the exception of no-malloc nt)
* and this buffer will *not* be nul-terminated
* @return number of bytes written to buf, or -1 w/ errno; if the
* return is equal to bufsiz then truncation may have occurred
* @error EINVAL if path isn't a symbolic link
* @asyncsignalsafe
*/
ssize_t readlinkat(int dirfd, const char *path, char *buf, size_t bufsiz) {
ssize_t bytes;
if ((IsAsan() && !__asan_is_valid(buf, bufsiz)) || (bufsiz && !buf)) {
bytes = efault();
} else if (_weaken(__zipos_notat) &&
(bytes = __zipos_notat(dirfd, path)) == -1) {
STRACE("TODO: zipos support for readlinkat");
} else if (!IsWindows()) {
bytes = sys_readlinkat(dirfd, path, buf, bufsiz);
} else {
bytes = sys_readlinkat_nt(dirfd, path, buf, bufsiz);
}
STRACE("readlinkat(%s, %#s, [%#.*s]) → %d% m", DescribeDirfd(dirfd), path,
MAX(0, bytes), buf, bytes);
return bytes;
}