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Ensure io requests are always capped at 0x7ffff000

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This gives us the Linux behavior across platforms.

Fixes #1189
This commit is contained in:
Justine Tunney 2024-05-26 16:53:13 -07:00
parent 6cf9b9e0fc
commit af3f62a71a
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GPG key ID: BE714B4575D6E328
10 changed files with 268 additions and 81 deletions
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94
libc/calls/writev.c
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@ -27,8 +27,71 @@
#include "libc/intrin/likely.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/limits.h"
#include "libc/runtime/stack.h"
#include "libc/sock/internal.h"
#include "libc/stdckdint.h"
#include "libc/sysv/errfuns.h"
#include "libc/vga/vga.internal.h"
static size_t SumIovecBytes(const struct iovec *iov, int iovlen) {
size_t count = 0;
for (int i = 0; i < iovlen; ++i)
if (ckd_add(&count, count, iov[i].iov_len))
count = SIZE_MAX;
return count;
}
static ssize_t writev_impl(int fd, const struct iovec *iov, int iovlen) {
if (fd < 0)
return ebadf();
if (iovlen < 0)
return einval();
if (IsAsan() && !__asan_is_valid_iov(iov, iovlen))
return efault();
if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip)
return ebadf(); // posix specifies this when not open()'d for writing
// XNU and BSDs will EINVAL if requested bytes exceeds INT_MAX
// this is inconsistent with Linux which ignores huge requests
if (!IsLinux()) {
size_t sum, remain = 0x7ffff000;
if ((sum = SumIovecBytes(iov, iovlen)) > remain) {
struct iovec *iov2;
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Walloca-larger-than="
iov2 = alloca(iovlen * sizeof(struct iovec));
CheckLargeStackAllocation(iov2, iovlen * sizeof(struct iovec));
#pragma GCC pop_options
for (int i = 0; i < iovlen; ++i) {
iov2[i] = iov[i];
if (remain >= iov2[i].iov_len) {
remain -= iov2[i].iov_len;
} else {
iov2[i].iov_len = remain;
remain = 0;
}
}
iov = iov2;
}
}
if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
if (iovlen == 1) {
return sys_write(fd, iov[0].iov_base, iov[0].iov_len);
} else {
return sys_writev(fd, iov, iovlen);
}
} else if (fd >= g_fds.n) {
return ebadf();
} else if (IsMetal()) {
return sys_writev_metal(g_fds.p + fd, iov, iovlen);
} else if (IsWindows()) {
return sys_writev_nt(fd, iov, iovlen);
} else {
return enosys();
}
}
/**
* Writes data from multiple buffers.
@ -45,6 +108,11 @@
* been committed. It can also happen if we need to polyfill this system
* call using write().
*
* It's possible for file write request to be partially completed. For
* example, if the sum of `iov` lengths exceeds 0x7ffff000 then bytes
* beyond that will be ignored. This is a Linux behavior that Cosmo
* polyfills across platforms.
*
* @return number of bytes actually handed off, or -1 w/ errno
* @cancelationpoint
* @restartable
@ -52,31 +120,7 @@
ssize_t writev(int fd, const struct iovec *iov, int iovlen) {
ssize_t rc;
BEGIN_CANCELATION_POINT;
if (fd < 0) {
rc = ebadf();
} else if (iovlen < 0) {
rc = einval();
} else if (IsAsan() && !__asan_is_valid_iov(iov, iovlen)) {
rc = efault();
} else if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
rc = ebadf(); // posix specifies this when not open()'d for writing
} else if (IsLinux() || IsXnu() || IsFreebsd() || IsOpenbsd() || IsNetbsd()) {
if (iovlen == 1) {
rc = sys_write(fd, iov[0].iov_base, iov[0].iov_len);
} else {
rc = sys_writev(fd, iov, iovlen);
}
} else if (fd >= g_fds.n) {
rc = ebadf();
} else if (IsMetal()) {
rc = sys_writev_metal(g_fds.p + fd, iov, iovlen);
} else if (IsWindows()) {
rc = sys_writev_nt(fd, iov, iovlen);
} else {
rc = enosys();
}
rc = writev_impl(fd, iov, iovlen);
END_CANCELATION_POINT;
STRACE("writev(%d, %s, %d) → %'ld% m", fd,
DescribeIovec(rc != -1 ? rc : -2, iov, iovlen), iovlen, rc);