cosmopolitan/libc/runtime/zipos-seek.c
Justine Tunney 965516e313
Make improvements for Actually Portable Emacs
- Get SIGWINCH working again on the New Technology
- Correctly handle O_NOFOLLOW in open() on Windows
- Implement synthetic umask() functionality on Windows
- Do a better job managing file execute access on Windows
- Fill in `st_uid` and `st_gid` with username hash on Windows
- Munge UNICODE control pictures into control codes on Windows
- Do a better job ensuring Windows console settings are restored
- Introduce KPRINTF_LOG environment variable to log kprintf to a file
2023-08-19 06:44:58 -07:00

81 lines
3.3 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/runtime/zipos.internal.h"
#include "libc/stdckdint.h"
#include "libc/sysv/consts/s.h"
#include "libc/sysv/errfuns.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
#include "libc/zip.internal.h"
static int64_t __zipos_seek_impl(struct ZiposHandle *h, int64_t offset,
unsigned whence) {
int64_t pos;
if (h->cfile == ZIPOS_SYNTHETIC_DIRECTORY ||
S_ISDIR(GetZipCfileMode(h->zipos->map + h->cfile))) {
return eisdir();
}
switch (whence) {
case SEEK_SET:
if (offset >= 0) {
return offset;
} else {
return einval();
}
case SEEK_CUR:
if (!ckd_add(&pos, h->pos, offset)) {
if (pos >= 0) {
return pos;
} else {
return einval();
}
} else {
return eoverflow();
}
case SEEK_END:
if (!ckd_sub(&pos, h->size, offset)) {
if (pos >= 0) {
return pos;
} else {
return einval();
}
} else {
return eoverflow();
}
default:
return einval();
}
}
/**
* 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_seek(struct ZiposHandle *h, int64_t offset, unsigned whence) {
int64_t pos;
if ((pos = __zipos_seek_impl(h, offset, whence)) != -1) {
h->pos = pos;
}
return pos;
}