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/*-*- 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 2020 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/calls.h"
#include "libc/errno.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/consts/o.h"
/**
* Returns current position of stream.
*
* @param stream is a non-null stream handle
* @returns current byte offset from beginning, or -1 w/ errno
*/
int64_t ftello(FILE *f) {
ssize_t rc;
int64_t pos;
uint32_t skew;
if (f->fd != -1) {
if (f->beg && !f->end && (f->iomode & O_ACCMODE) != O_RDONLY) {
if ((rc = write(f->fd, f->buf, f->beg)) == -1) {
f->state = errno;
return -1;
}
if (rc != f->beg) abort();
f->beg = 0;
}
if ((pos = lseek(f->fd, 0, SEEK_CUR)) != -1) {
if (f->beg < f->end) pos -= f->end - f->beg;
return pos;
} else {
f->state = errno == ESPIPE ? EBADF : errno;
return -1;
}
} else {
return f->beg;
}
}
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