readlink.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et 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.      │
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│ 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/calls.h"
#include "libc/sysv/consts/at.h"

/**
 * Reads symbolic link.
 *
 * @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
 * @see readlinkat(AT_FDCWD, ...) for modern version of this
 * @error EINVAL if path isn't a symbolic link
 * @asyncsignalsafe
 */
ssize_t readlink(const char *path, char *buf, size_t bufsiz) {
  return readlinkat(AT_FDCWD, path, buf, bufsiz);
}