mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-06-28 15:28:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Ensure io requests are always capped at 0x7ffff000

Browse source 
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
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
10 changed files with 268 additions and 81 deletions
Download patch file Download diff file Expand all files Collapse all files

54
libc/calls/pwritev.c
View file

@ -28,28 +28,57 @@
#include "libc/intrin/likely.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/limits.h"
#include "libc/mem/alloca.h"
#include "libc/runtime/stack.h"
#include "libc/stdckdint.h"
#include "libc/sysv/errfuns.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 Pwritev(int fd, const struct iovec *iov, int iovlen,
int64_t off) {
int i, e;
size_t sent;
ssize_t rc, toto;
if (fd < 0) {
if (fd < 0)
return ebadf();
}
if (iovlen < 0) {
if (iovlen < 0)
return einval();
}
if (IsAsan() && !__asan_is_valid_iov(iov, iovlen)) {
if (IsAsan() && !__asan_is_valid_iov(iov, iovlen))
return efault();
}
if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip)
return ebadf();
// 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 (IsWindows()) {
@ -116,6 +145,11 @@ static ssize_t Pwritev(int fd, const struct iovec *iov, int iovlen,
* been committed. It can also happen if we need to polyfill this system
* call using pwrite().
*
* 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 sent, or -1 w/ errno
* @cancelationpoint
* @asyncsignalsafe