mirror of
https://github.com/jart/cosmopolitan.git
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3f0bcdc3ef
- Exhaustively document cancellation points - Rename SIGCANCEL to SIGTHR just like BSDs - Further improve POSIX thread cancellations - Ensure asynchronous cancellations work correctly - Elevate the quality of getrandom() and getentropy() - Make futexes cancel correctly on OpenBSD 6.x and 7.x - Add reboot.com and shutdown.com to examples directory - Remove underscore prefix from awesome timespec_*() APIs - Create assertions that help verify our cancellation points - Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)
91 lines
4.6 KiB
C
91 lines
4.6 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/cp.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/errno.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/intrin/weaken.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/zipos/zipos.internal.h"
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/**
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* Changes size of file.
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*
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* If the file size is increased, the extended area shall appear as if
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* it were zero-filled. If your file size is decreased, the extra data
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* shall be lost.
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*
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* Some operating systems implement an optimization, where `length` is
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* treated as a logical size and the requested physical space won't be
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* allocated until non-zero values get written into it. Our tests show
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* this happens on Linux (usually with 4096 byte granularity), FreeBSD
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* (which favors 512-byte granularity), and MacOS (prefers 4096 bytes)
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* however Windows, OpenBSD, and NetBSD always reserve physical space.
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* This may be inspected using stat() then consulting stat::st_blocks.
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*
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* @param path is name of file that shall be resized
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* @return 0 on success, or -1 w/ errno
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* @raise EINVAL if `length` is negative
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* @raise EINTR if signal was delivered instead
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* @raise ECANCELED if thread was cancelled in masked mode
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* @raise EFBIG or EINVAL if `length` is too huge
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* @raise EFAULT if `path` points to invalid memory
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* @raise ENOTSUP if `path` is a zip filesystem path
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* @raise EACCES if we don't have permission to search a component of `path`
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* @raise ENOTDIR if a directory component in `path` exists as non-directory
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* @raise ENAMETOOLONG if symlink-resolved `path` length exceeds `PATH_MAX`
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* @raise ENAMETOOLONG if component in `path` exists longer than `NAME_MAX`
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* @raise ELOOP if a loop was detected resolving components of `path`
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* @raise ENOENT if `path` doesn't exist or is an empty string
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* @raise ETXTBSY if `path` is an executable being executed
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* @raise EROFS if `path` is on a read-only filesystem
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* @raise ENOSYS on bare metal
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* @cancellationpoint
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* @see ftruncate()
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* @threadsafe
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*/
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int truncate(const char *path, int64_t length) {
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int rc;
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struct ZiposUri zipname;
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BEGIN_CANCELLATION_POINT;
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if (IsMetal()) {
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rc = enosys();
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} else if (!path || (IsAsan() && !__asan_is_valid_str(path))) {
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rc = efault();
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} else if (_weaken(__zipos_parseuri) &&
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_weaken(__zipos_parseuri)(path, &zipname) != -1) {
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rc = enotsup();
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} else if (!IsWindows()) {
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rc = sys_truncate(path, length, length);
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if (IsNetbsd() && rc == -1 && errno == ENOSPC) {
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errno = EFBIG; // POSIX doesn't specify ENOSPC for truncate()
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}
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} else {
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rc = sys_truncate_nt(path, length);
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}
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END_CANCELLATION_POINT;
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STRACE("truncate(%#s, %'ld) → %d% m", path, length, rc);
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return rc;
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}
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