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ccbae7799e
This change also found a few POSIX compliance bugs with errnos. Another bug was discovered where, on Windows, pread() and pwrite() could modify the file position in cases where ReadFile() returned an error e.g. when seeking past the end of file. We also have more tests!
84 lines
4.4 KiB
C
84 lines
4.4 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/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 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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* @see ftruncate()
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* @threadsafe
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*/
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int truncate(const char *path, uint64_t length) {
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int rc;
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struct ZiposUri zipname;
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if (IsMetal()) {
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rc = enosys();
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} else if (!path || (IsAsan() && !__asan_is_valid(path, 1))) {
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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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STRACE("truncate(%#s, %'ld) → %d% m", path, length, rc);
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return rc;
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}
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