Support dirfd relative iops on Windows

We always favor calling functions like openat(), fstatat(), etc. because
Linux, XNU, FreeBSD, and OpenBSD all elected to support them, while some
systems like Android love them so much, that they stopped supporting the
old interfaces.

This change ensures that when dirfd is actually a dirfd and not AT_FDCWD
we'll do the right thing on Windows NT. We use an API that's been around
since Vista to accomplish that.

This change also adds exponential backoff to chdir() on Windows since it
seems almost as flaky on Windows 7 as the rmdir() function.
This commit is contained in:
Justine Tunney 2021-01-30 01:49:43 -08:00
parent b8d26e2418
commit 417797d218
42 changed files with 361 additions and 241 deletions

65
libc/calls/unlinkat-nt.c Normal file
View file

@ -0,0 +1,65 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/calls/internal.h"
#include "libc/errno.h"
#include "libc/nt/errors.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/nt/synchronization.h"
#include "libc/sysv/consts/at.h"
static textwindows int unlink$nt(const char16_t *path) {
if (DeleteFile(path)) {
return 0;
} else {
return __winerr();
}
}
static textwindows int rmdir$nt(const char16_t *path) {
int e, ms;
for (ms = 1;; ms *= 2) {
if (RemoveDirectory(path)) return 0;
/*
* Files can linger, for absolutely no reason.
* Possibly some Windows Defender bug on Win7.
* Sleep for up to one second w/ expo backoff.
* Alternative is use Microsoft internal APIs.
* Never could have imagined it'd be this bad.
*/
if ((e = GetLastError()) == kNtErrorDirNotEmpty && ms <= 512) {
Sleep(ms);
continue;
} else {
break;
}
}
errno = e;
return -1;
}
textwindows int unlinkat$nt(int dirfd, const char *path, int flags) {
uint16_t path16[PATH_MAX];
if (__mkntpathat(dirfd, path, 0, path16) == -1) return -1;
if (flags & AT_REMOVEDIR) {
return rmdir$nt(path16);
} else {
return unlink$nt(path16);
}
}