/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â Copyright 2021 Justine Alexandra Roberts Tunney                              â
â                                                                              â
â Permission to use, copy, modify, and/or distribute this software for         â
â any purpose with or without fee is hereby granted, provided that the         â
â above copyright notice and this permission notice appear in all copies.      â
â                                                                              â
â THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                â
â WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                â
â WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             â
â AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         â
â DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        â
â PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               â
â TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             â
â PERFORMANCE OF THIS SOFTWARE.                                                â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/stdio/lock.internal.h"
#include "libc/stdio/stdio.h"

/**
 * Repositions open file stream.
 *
 * This function flushes the buffer (unless it's currently in the EOF
 * state) and then calls lseek() on the underlying file. If the stream
 * is in the EOF state, this function can be used to restore it without
 * needing to reopen the file.
 *
 * @param f is a non-null stream handle
 * @param offset is the byte delta
 * @param whence can be SEET_SET, SEEK_CUR, or SEEK_END
 * @returns 0 on success or -1 on error
 * @threadsafe
 */
int fseeko(FILE *f, int64_t offset, int whence) {
  int rc;
  flockfile(f);
  rc = fseeko_unlocked(f, offset, whence);
  STDIOTRACE("fseeko(%p, %'ld, %s) â %d %s", f, offset, DescribeWhence(whence),
             rc, DescribeStdioState(f->state));
  funlockfile(f);
  return rc;
}
