mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
2db2f40a98
This change gets GNU grep working. What caused it to not work, is it wouldn't write to an output file descriptor when its dev/ino equaled /dev/null's. So now we invent special dev/ino values for these files
88 lines
4.2 KiB
C
88 lines
4.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ Permission to use, copy, modify, and/or distribute this software for │
|
|
│ any purpose with or without fee is hereby granted, provided that the │
|
|
│ above copyright notice and this permission notice appear in all copies. │
|
|
│ │
|
|
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
|
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
|
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
|
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
|
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
|
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
|
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
|
│ PERFORMANCE OF THIS SOFTWARE. │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/assert.h"
|
|
#include "libc/calls/calls.h"
|
|
#include "libc/calls/cp.internal.h"
|
|
#include "libc/calls/internal.h"
|
|
#include "libc/calls/struct/iovec.h"
|
|
#include "libc/calls/struct/iovec.internal.h"
|
|
#include "libc/calls/syscall-sysv.internal.h"
|
|
#include "libc/dce.h"
|
|
#include "libc/intrin/asan.internal.h"
|
|
#include "libc/intrin/strace.internal.h"
|
|
#include "libc/intrin/weaken.h"
|
|
#include "libc/macros.internal.h"
|
|
#include "libc/runtime/runtime.h"
|
|
#include "libc/runtime/zipos.internal.h"
|
|
#include "libc/sysv/errfuns.h"
|
|
|
|
/**
|
|
* Reads from file at offset.
|
|
*
|
|
* This function never changes the current position of `fd`.
|
|
*
|
|
* @param fd is something open()'d earlier, noting pipes might not work
|
|
* @param buf is copied into, cf. copy_file_range(), sendfile(), etc.
|
|
* @param size in range [1..0x7ffff000] is reasonable
|
|
* @param offset is bytes from start of file at which read begins
|
|
* @return [1..size] bytes on success, 0 on EOF, or -1 w/ errno; with
|
|
* exception of size==0, in which case return zero means no error
|
|
* @raise ESPIPE if `fd` isn't seekable
|
|
* @raise EINVAL if `offset` is negative
|
|
* @raise EBADF if `fd` isn't an open file descriptor
|
|
* @raise EIO if a complicated i/o error happened
|
|
* @raise EINTR if signal was delivered instead
|
|
* @raise ECANCELED if thread was cancelled in masked mode
|
|
* @see pwrite(), write()
|
|
* @cancelationpoint
|
|
* @asyncsignalsafe
|
|
* @vforksafe
|
|
*/
|
|
ssize_t pread(int fd, void *buf, size_t size, int64_t offset) {
|
|
ssize_t rc;
|
|
BEGIN_CANCELATION_POINT;
|
|
|
|
if (offset < 0) {
|
|
rc = einval();
|
|
} else if (fd < 0) {
|
|
rc = ebadf();
|
|
} else if (IsAsan() && !__asan_is_valid(buf, size)) {
|
|
rc = efault();
|
|
} else if (__isfdkind(fd, kFdZip)) {
|
|
rc = _weaken(__zipos_read)(
|
|
(struct ZiposHandle *)(intptr_t)g_fds.p[fd].handle,
|
|
(struct iovec[]){{buf, size}}, 1, offset);
|
|
} else if (!IsWindows()) {
|
|
rc = sys_pread(fd, buf, size, offset, offset);
|
|
} else if (__isfdkind(fd, kFdSocket)) {
|
|
rc = espipe();
|
|
} else if (__isfdkind(fd, kFdFile) || __isfdkind(fd, kFdDevNull)) {
|
|
rc = sys_read_nt(fd, (struct iovec[]){{buf, size}}, 1, offset);
|
|
} else {
|
|
rc = ebadf();
|
|
}
|
|
npassert(rc == -1 || (size_t)rc <= size);
|
|
|
|
END_CANCELATION_POINT;
|
|
DATATRACE("pread(%d, [%#.*hhs%s], %'zu, %'zd) → %'zd% m", fd,
|
|
MAX(0, MIN(40, rc)), buf, rc > 40 ? "..." : "", size, offset, rc);
|
|
return rc;
|
|
}
|
|
|
|
__strong_reference(pread, pread64);
|