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Make more Windows socket fixes and improvements

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This change makes send() / sendto() always block on Windows. It's needed
because poll(POLLOUT) doesn't guarantee a socket is immediately writable
on Windows, and it caused rsync to fail because it made that assumption.
The only exception is when a SO_SNDTIMEO is specified which will EAGAIN.

Tests are added confirming MSG_WAITALL and MSG_NOSIGNAL work as expected
on all our supported OSes. Most of the platform-specific MSG_FOO magnums
have been deleted, with the exception of MSG_FASTOPEN. Your --strace log
will now show MSG_FOO flags as symbols rather than numbers.

I've also removed cv_wait_example_test because it's 0.3% flaky with Qemu
under system load since it depends on a process being readily scheduled.
This commit is contained in:
Justine Tunney 2024-09-18 19:54:56 -07:00
parent ce2fbf9325
commit 87a6669900
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GPG key ID: BE714B4575D6E328
41 changed files with 584 additions and 184 deletions
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31
libc/sock/recv.c
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@ -20,20 +20,40 @@
#include "libc/calls/internal.h"
#include "libc/calls/struct/iovec.internal.h"
#include "libc/dce.h"
#include "libc/intrin/describeflags.h"
#include "libc/intrin/strace.h"
#include "libc/sock/internal.h"
#include "libc/sock/sock.h"
#include "libc/sock/syscall_fd.internal.h"
#include "libc/sysv/consts/msg.h"
#include "libc/sysv/errfuns.h"
/**
* Receives data from network socket.
*
* Calling `recv(fd, p, n, 0)` is equivalent to `read(fd, p, n)`.
*
* Unlike files where the OS tries very hard to fulfill the entire
* requested `size` before returning, read operations on sockets aim to
* return as quickly as possible. For example, if 10 bytes are requested
* and a packet comes in with only 5 bytes, then recv() will most likely
* return those 5 bytes before waiting longer. The `MSG_WAITALL` flag
* may be passed when waiting longer is desired. In that case, short
* reads should only be possible when the connection status changes or
* the receive operation is interrupted by a signal.
*
* @param fd is the file descriptor returned by socket()
* @param buf is where received network data gets copied
* @param size is the byte capacity of buf
* @param flags can have `MSG_OOB`, `MSG_PEEK`, `MSG_DONTWAIT`, `MSG_WAITALL`
* @return number of bytes received, 0 on remote close, or -1 w/ errno
* @raise EINTR if signal handler was called instead
* @raise EINVAL if unknown bits were passed in `flags`
* @raise EINVAL if flag isn't supported by host operating system
* @raise EINVAL if `MSG_WAITALL` and `MSG_PEEK` were both passed
* @raise EBADF if `fd` is an invalid file descriptor
* @raise EAGAIN if `MSG_DONTWAIT` was passed and no data was available
* @raise EAGAIN if `O_NONBLOCK` is in play and no data was available
* @error EINTR, EHOSTUNREACH, ECONNRESET (UDP ICMP Port Unreachable),
* EPIPE (if MSG_NOSIGNAL), EMSGSIZE, ENOTSOCK, EFAULT, etc.
* @cancelationpoint
@ -44,7 +64,11 @@ ssize_t recv(int fd, void *buf, size_t size, int flags) {
ssize_t rc;
BEGIN_CANCELATION_POINT;
if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
if ((flags & (MSG_WAITALL | MSG_PEEK)) == (MSG_WAITALL | MSG_PEEK)) {
// this is possible on some OSes like Linux but it breaks FreeBSD
// and Windows will raise EOPNOTSUPP when it gets passed together
return einval();
} else if (fd < g_fds.n && g_fds.p[fd].kind == kFdZip) {
rc = enotsock();
} else if (!IsWindows()) {
rc = sys_recvfrom(fd, buf, size, flags, 0, 0);
@ -65,7 +89,8 @@ ssize_t recv(int fd, void *buf, size_t size, int flags) {
}
END_CANCELATION_POINT;
DATATRACE("recv(%d, [%#.*hhs%s], %'zu, %#x) → %'ld% lm", fd,
MAX(0, MIN(40, rc)), buf, rc > 40 ? "..." : "", size, flags, rc);
DATATRACE("recv(%d, [%#.*hhs%s], %'zu, %s) → %'ld% lm", fd,
MAX(0, MIN(40, rc)), buf, rc > 40 ? "..." : "", size,
DescribeMsg(flags), rc);
return rc;
}