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https://github.com/jart/cosmopolitan.git
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ff77f2a6af
- This change fixes a bug that allowed unbuffered printf() output (to streams like stderr) to be truncated. This regression was introduced some time between now and the last release. - POSIX specifies all functions as thread safe by default. This change works towards cleaning up our use of the @threadsafe / @threadunsafe documentation annotations to reflect that. The goal is (1) to use @threadunsafe to document functions which POSIX say needn't be thread safe, and (2) use @threadsafe to document functions that we chose to implement as thread safe even though POSIX didn't mandate it. - Tidy up the clock_gettime() implementation. We're now trying out a cleaner approach to system call support that aims to maintain the Linux errno convention as long as possible. This also fixes bugs that existed previously, where the vDSO errno wasn't being translated properly. The gettimeofday() system call is now a wrapper for clock_gettime(), which reduces bloat in apps that use both. - The recently-introduced improvements to the execute bit on Windows has had bugs fixed. access(X_OK) on a directory on Windows now succeeds. fstat() will now perform the MZ/#! ReadFile() operation correctly. - Windows.h is no longer included in libc/isystem/, because it confused PCRE's build system into thinking Cosmopolitan is a WIN32 platform. Cosmo's Windows.h polyfill was never even really that good, since it only defines a subset of the subset of WIN32 APIs that Cosmo defines. - The setlongerjmp() / longerjmp() APIs are removed. While they're nice APIs that are superior to the standardized setjmp / longjmp functions, they weren't superior enough to not be dead code in the monorepo. If you use these APIs, please file an issue and they'll be restored. - The .com appending magic has now been removed from APE Loader.
96 lines
4.8 KiB
C
96 lines
4.8 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/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/describeflags.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/log/backtrace.internal.h"
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#include "libc/runtime/zipos.internal.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Changes current position of file descriptor, e.g.
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*
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* int fd = open("hello.bin", O_RDONLY);
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* lseek(fd, 100, SEEK_SET); // set position to 100th byte
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* read(fd, buf, 8); // read bytes 100 through 107
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*
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* This function may be used to inspect the current position:
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*
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* int64_t pos = lseek(fd, 0, SEEK_CUR);
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*
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* You may seek past the end of file. If a write happens afterwards
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* then the gap leading up to it will be filled with zeroes. Please
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* note that lseek() by itself will not extend the physical medium.
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*
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* If dup() is used then the current position will be shared across
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* multiple file descriptors. If you seek in one it will implicitly
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* seek the other too.
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*
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* The current position of a file descriptor is shared between both
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* processes and threads. For example, if an fd is inherited across
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* fork(), and both the child and parent want to read from it, then
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* changes made by one are observable to the other.
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*
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* The pread() and pwrite() functions obfuscate the need for having
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* global shared file position state. Consider using them, since it
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* helps avoid the gotchas of this interface described above.
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*
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* This function is supported by all OSes within our support vector
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* and our unit tests demonstrate the behaviors described above are
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* consistent across platforms.
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*
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* @param fd is a number returned by open()
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* @param offset is 0-indexed byte count w.r.t. `whence`
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* @param whence can be one of:
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* - `SEEK_SET`: Sets the file position to `offset` [default]
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* - `SEEK_CUR`: Sets the file position to `position + offset`
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* - `SEEK_END`: Sets the file position to `filesize + offset`
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* @return new position relative to beginning, or -1 w/ errno
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* @raise ESPIPE if `fd` is a pipe, socket, or fifo
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* @raise EBADF if `fd` isn't an open file descriptor
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* @raise EINVAL if resulting offset would be negative
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* @raise EINVAL if `whence` isn't valid
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* @asyncsignalsafe
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* @vforksafe
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*/
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int64_t lseek(int fd, int64_t offset, int 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_seek)(
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(struct ZiposHandle *)(intptr_t)g_fds.p[fd].handle, offset, whence);
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} else if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd()) {
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rc = sys_lseek(fd, offset, whence, 0);
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} else if (IsNetbsd()) {
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rc = sys_lseek(fd, offset, offset, whence);
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} else if (IsWindows()) {
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rc = sys_lseek_nt(fd, offset, whence);
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} else {
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rc = enosys();
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}
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STRACE("lseek(%d, %'ld, %s) → %'ld% m", fd, offset, DescribeWhence(whence),
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rc);
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return rc;
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}
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__strong_reference(lseek, lseek64);
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