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d1d4388201
It hasn't been helpful enough to be justify the maintenance burden. What actually does help is mprotect(), kprintf(), --ftrace and --strace which can always be counted upon to work correctly. We aren't losing much with this change. Support for ASAN on AARCH64 was never implemented. Applying ASAN to the core libc runtimes was disabled many months ago. If there is some way to have an ASAN runtime for user programs that is less invasive we can potentially consider reintroducing support. But now is premature.
125 lines
5.3 KiB
C
125 lines
5.3 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/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/iovec.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/likely.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/limits.h"
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#include "libc/runtime/stack.h"
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#include "libc/sock/internal.h"
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#include "libc/stdckdint.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/vga/vga.internal.h"
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static size_t SumIovecBytes(const struct iovec *iov, int iovlen) {
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size_t count = 0;
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for (int i = 0; i < iovlen; ++i)
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if (ckd_add(&count, count, iov[i].iov_len))
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count = SIZE_MAX;
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return count;
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}
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static ssize_t writev_impl(int fd, const struct iovec *iov, int iovlen) {
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if (fd < 0)
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return ebadf();
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if (iovlen < 0)
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return einval();
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if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip)
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return ebadf(); // posix specifies this when not open()'d for writing
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// XNU and BSDs will EINVAL if requested bytes exceeds INT_MAX
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// this is inconsistent with Linux which ignores huge requests
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if (!IsLinux()) {
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size_t sum, remain = 0x7ffff000;
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if ((sum = SumIovecBytes(iov, iovlen)) > remain) {
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struct iovec *iov2;
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#pragma GCC push_options
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#pragma GCC diagnostic ignored "-Walloca-larger-than="
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iov2 = alloca(iovlen * sizeof(struct iovec));
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CheckLargeStackAllocation(iov2, iovlen * sizeof(struct iovec));
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#pragma GCC pop_options
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for (int i = 0; i < iovlen; ++i) {
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iov2[i] = iov[i];
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if (remain >= iov2[i].iov_len) {
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remain -= iov2[i].iov_len;
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} else {
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iov2[i].iov_len = remain;
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remain = 0;
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}
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}
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iov = iov2;
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}
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}
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if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
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if (iovlen == 1) {
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return sys_write(fd, iov[0].iov_base, iov[0].iov_len);
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} else {
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return sys_writev(fd, iov, iovlen);
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}
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} else if (fd >= g_fds.n) {
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return ebadf();
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} else if (IsMetal()) {
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return sys_writev_metal(g_fds.p + fd, iov, iovlen);
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} else if (IsWindows()) {
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return sys_writev_nt(fd, iov, iovlen);
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} else {
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return enosys();
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}
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}
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/**
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* Writes data from multiple buffers.
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*
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* This is the same thing as write() except it has multiple buffers.
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* This yields a performance boost in situations where it'd be expensive
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* to stitch data together using memcpy() or issuing multiple syscalls.
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* This wrapper is implemented so that writev() calls where iovlen<2 may
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* be passed to the kernel as write() instead. This yields a 100 cycle
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* performance boost in the case of a single small iovec.
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*
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* Please note that it's not an error for a short write to happen. This
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* can happen in the kernel if EINTR happens after some of the write has
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* been committed. It can also happen if we need to polyfill this system
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* call using write().
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*
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* It's possible for file write request to be partially completed. For
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* example, if the sum of `iov` lengths exceeds 0x7ffff000 then bytes
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* beyond that will be ignored. This is a Linux behavior that Cosmo
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* polyfills across platforms.
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*
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* @return number of bytes actually handed off, or -1 w/ errno
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* @cancelationpoint
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* @restartable
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*/
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ssize_t writev(int fd, const struct iovec *iov, int iovlen) {
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ssize_t rc;
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BEGIN_CANCELATION_POINT;
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rc = writev_impl(fd, iov, iovlen);
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END_CANCELATION_POINT;
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STRACE("writev(%d, %s, %d) → %'ld% m", fd,
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DescribeIovec(rc != -1 ? rc : -2, iov, iovlen), iovlen, rc);
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return rc;
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}
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