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Kernel: Make writev() work again

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Vector::ensure_capacity() makes sure the underlying vector buffer can
contain all the data, but it doesn't update the Vector::size().

As a result, writev() would simply collect all the buffers to write,
and then do nothing.
This commit is contained in:
Andreas Kling 2020-01-26 10:10:15 +01:00
parent b93f6b07c2
commit b011857e4f
2 changed files with 35 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

2
Kernel/Process.cpp
View file

@ -1539,7 +1539,7 @@ ssize_t Process::sys$writev(int fd, const struct iovec* iov, int iov_count)
u64 total_length = 0;
Vector<iovec, 32> vecs;
vecs.ensure_capacity(iov_count);
vecs.resize(iov_count);
copy_from_user(vecs.data(), iov, iov_count * sizeof(iovec));
for (auto& vec : vecs) {
if (!validate_read(vec.iov_base, vec.iov_len))

34
Userland/test_io.cpp
View file

@ -28,8 +28,10 @@
#include <AK/Types.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <unistd.h>
#define EXPECT_ERROR_2(err, syscall, arg1, arg2) \
@ -255,6 +257,37 @@ void test_rmdir_while_inside_dir()
ASSERT(rc == 0);
}
void test_writev()
{
int pipefds[2];
pipe(pipefds);
iovec iov[2];
iov[0].iov_base = const_cast<void*>((const void*)"Hello");
iov[0].iov_len = 5;
iov[1].iov_base = const_cast<void*>((const void*)"Friends");
iov[1].iov_len = 7;
int nwritten = writev(pipefds[1], iov, 2);
if (nwritten < 0) {
perror("writev");
ASSERT_NOT_REACHED();
}
if (nwritten != 12) {
fprintf(stderr, "Didn't write 12 bytes to pipe with writev\n");
ASSERT_NOT_REACHED();
}
char buffer[32];
int nread = read(pipefds[0], buffer, sizeof(buffer));
if (nread != 12 || memcmp(buffer, "HelloFriends", 12)) {
fprintf(stderr, "Didn't read the expected data from pipe after writev\n");
ASSERT_NOT_REACHED();
}
close(pipefds[0]);
close(pipefds[1]);
}
int main(int, char**)
{
int rc;
@ -280,6 +313,7 @@ int main(int, char**)
test_unlink_symlink();
test_eoverflow();
test_rmdir_while_inside_dir();
test_writev();
EXPECT_ERROR_2(EPERM, link, "/", "/home/anon/lolroot");