cosmopolitan/libc/zipos/lseek.c
Justine Tunney 4a59210008
Introduce #include <cosmo.h> to toolchain users
This change improves the way internal APIs are being hidden behind the
`COSMO` define. The cosmo.h header will take care of defining that, so
that a separate define statement isn't needed. This change also does a
lot more to define which APIs are standard, and which belong to Cosmo.
2023-06-09 18:03:05 -07:00

58 lines
2.7 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/calls.h"
#include "libc/sysv/errfuns.h"
#include "libc/thread/thread.h"
#include "libc/zip.internal.h"
#include "libc/zipos/zipos.internal.h"
/**
* Changes current position of zip file handle.
*
* @param offset is the relative byte count
* @param whence can be SEEK_SET, SEEK_CUR, or SEEK_END
* @return new position relative to beginning, or -1 on error
* @asyncsignalsafe
*/
int64_t __zipos_lseek(struct ZiposHandle *h, int64_t offset, unsigned whence) {
int64_t rc;
pthread_mutex_lock(&h->lock);
switch (whence) {
case SEEK_SET:
rc = offset;
break;
case SEEK_CUR:
rc = h->pos + offset;
break;
case SEEK_END:
rc = h->size - offset;
break;
default:
rc = -1;
break;
}
if (rc >= 0) {
h->pos = rc;
} else {
rc = einval();
}
pthread_mutex_unlock(&h->lock);
return rc;
}