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Support non-blocking i/o across platforms

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This change introduces new tests for `O_NONBLOCK` and `SOCK_NONBLOCK` to
confirm that non-blocking i/o is now working on all supported platforms,
including Windows. For example, you can now say on Windows, MacOS, etc.:

    socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);

To create a non-blocking IPv4 TCP socket. Or you can enable non-blocking
i/o on an existing socket / pipe / etc. file descriptor by calling fcntl

    fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);

This functionality is polyfilled on older Linux kernels too, e.g. RHEL5.
Now that fcntl() support is much better the FIOCLEX / FIONCLEX polyfills
for ioctl() have been removed since they're ugly non-POSIX diameond APIs

This change fixes a weakness in kprintf() that was causing Windows trace
tools to frequently crash.
This commit is contained in:
Justine Tunney 2023-07-23 02:56:47 -07:00
parent 5c9e03e3e0
commit 1d4eb08fa1
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
102 changed files with 678 additions and 331 deletions
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49
libc/calls/fcntl-nt.c
View file

@ -36,10 +36,13 @@
#include "libc/nt/runtime.h"
#include "libc/nt/struct/byhandlefileinformation.h"
#include "libc/nt/struct/overlapped.h"
#include "libc/nt/winsock.h"
#include "libc/sock/internal.h"
#include "libc/stdckdint.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/fd.h"
#include "libc/sysv/consts/fio.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"
#include "libc/thread/thread.h"
@ -307,21 +310,49 @@ static textwindows int sys_fcntl_nt_dupfd(int fd, int cmd, int start) {
return sys_dup_nt(fd, -1, (cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0), start);
}
static textwindows int sys_fcntl_nt_setfl(int fd, unsigned *flags, unsigned arg,
unsigned supported) {
unsigned old, neu, changed, other, allowed;
old = *flags & supported;
other = *flags & ~supported;
neu = arg & supported;
changed = old ^ neu;
// you may change the following access mode flags:
//
// - O_NONBLOCK make read() raise EAGAIN
// - O_NDELAY same thing as O_NONBLOCK
//
allowed = O_NONBLOCK;
if (changed & ~allowed) {
// the following access mode flags are supported, but it's currently
// not possible to change them on windows.
//
// - O_APPEND tried to support but failed
// - O_RANDOM use posix_fadvise() instead
// - O_SEQUENTIAL use posix_fadvise() instead
// - O_DIRECT possibly in future?
// - O_DSYNC possibly in future?
// - O_RSYNC possibly in future?
// - O_SYNC possibly in future?
//
return enotsup();
}
// 1. ignore flags that aren't access mode flags
// 2. return zero if nothing's changed
*flags = other | neu;
return 0;
}
textwindows int sys_fcntl_nt(int fd, int cmd, uintptr_t arg) {
int rc;
uint32_t flags;
int access_mode_flags = O_ACCMODE | O_APPEND | O_ASYNC | O_DIRECT |
O_NOATIME | O_NONBLOCK | O_RANDOM | O_SEQUENTIAL;
if (__isfdkind(fd, kFdFile) || __isfdkind(fd, kFdSocket)) {
if (cmd == F_GETFL) {
rc = g_fds.p[fd].flags &
(O_ACCMODE | O_APPEND | O_ASYNC | O_DIRECT | O_NOATIME | O_NONBLOCK |
O_RANDOM | O_SEQUENTIAL);
rc = g_fds.p[fd].flags & access_mode_flags;
} else if (cmd == F_SETFL) {
// O_APPEND doesn't appear to be tunable at cursory glance
// O_NONBLOCK might require we start doing all i/o in threads
// O_DSYNC / O_RSYNC / O_SYNC maybe if we fsync() everything
// O_DIRECT | O_RANDOM | O_SEQUENTIAL | O_NDELAY possible but
// not worth it.
rc = enosys();
rc = sys_fcntl_nt_setfl(fd, &g_fds.p[fd].flags, arg, access_mode_flags);
} else if (cmd == F_GETFD) {
if (g_fds.p[fd].flags & O_CLOEXEC) {
rc = FD_CLOEXEC;