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https://github.com/jart/cosmopolitan.git
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eeb20775d2
This will help C++ code that uses exceptions to be tinier. For example, this change shaves away 1000 lines of assembly code from LLVM's libcxx, which is 0.7% of all assembly instructions in the entire library.
89 lines
3.9 KiB
C
89 lines
3.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/cp.internal.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/struct/fd.internal.h"
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#include "libc/calls/struct/iovec.h"
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#include "libc/calls/struct/iovec.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/asan.internal.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/macros.internal.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Writes to file at offset.
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*
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* This function never changes the current position of `fd`.
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*
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* @param fd is something open()'d earlier, noting pipes might not work
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* @param buf is copied from, cf. copy_file_range(), sendfile(), etc.
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* @param size in range [1..0x7ffff000] is reasonable
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* @param offset is bytes from start of file at which write begins,
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* which can exceed or overlap the end of file, in which case your
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* file will be extended
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* @return [1..size] bytes on success, or -1 w/ errno; noting zero is
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* impossible unless size was passed as zero to do an error check
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* @see pread(), write()
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* @cancelationpoint
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* @asyncsignalsafe
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* @vforksafe
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*/
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ssize_t pwrite(int fd, const void *buf, size_t size, int64_t offset) {
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ssize_t rc;
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size_t wrote;
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BEGIN_CANCELATION_POINT;
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if (offset < 0) {
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rc = einval();
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} else if (fd == -1) {
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rc = ebadf();
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} else if (IsAsan() && !__asan_is_valid(buf, size)) {
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rc = efault();
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} else if (__isfdkind(fd, kFdZip)) {
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rc = ebadf();
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} else if (!IsWindows()) {
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rc = sys_pwrite(fd, buf, size, offset, offset);
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} else if (__isfdkind(fd, kFdSocket)) {
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rc = espipe();
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} else if (__isfdkind(fd, kFdFile) || __isfdkind(fd, kFdDevNull)) {
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rc = sys_write_nt(fd, (struct iovec[]){{(void *)buf, size}}, 1, offset);
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} else {
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return ebadf();
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}
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if (rc != -1) {
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wrote = (size_t)rc;
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if (!wrote) {
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npassert(size == 0);
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} else {
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npassert(wrote <= size);
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}
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}
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END_CANCELATION_POINT;
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DATATRACE("pwrite(%d, %#.*hhs%s, %'zu, %'zd) → %'zd% m", fd,
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MAX(0, MIN(40, rc)), buf, rc > 40 ? "..." : "", size, offset, rc);
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return rc;
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}
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__weak_reference(pwrite, pwrite64);
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