mirror of
https://github.com/jart/cosmopolitan.git
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52 lines
3 KiB
C
52 lines
3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/strace.internal.h"
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#include "libc/calls/syscall-nt.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/weaken.h"
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#include "libc/log/backtrace.internal.h"
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#include "libc/zipos/zipos.internal.h"
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/**
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* Changes current position of file descriptor/handle.
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*
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* @param fd is a number returned by open()
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* @param offset is the relative byte count
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* @param whence can be SEEK_SET, SEEK_CUR, or SEEK_END
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* @return new position relative to beginning, or -1 on error
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* @asyncsignalsafe
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*/
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int64_t lseek(int fd, int64_t offset, unsigned whence) {
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int64_t rc;
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if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
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rc = weaken(__zipos_lseek)(
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(struct ZiposHandle *)(intptr_t)g_fds.p[fd].handle, offset, whence);
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} else if (!IsWindows() && !IsOpenbsd() && !IsNetbsd()) {
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rc = sys_lseek(fd, offset, whence, 0);
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} else if (IsOpenbsd() || IsNetbsd()) {
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rc = sys_lseek(fd, offset, offset, whence);
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} else {
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rc = sys_lseek_nt(fd, offset, whence);
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}
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STRACE("lseek(%d, %'ld, %d) → %'ld% m", fd, offset, whence, rc);
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return rc;
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}
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