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Support dirfd relative iops on Windows

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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
Download patch file Download diff file Expand all files Collapse all files

51
libc/calls/open-nt.c
View file

@ -30,18 +30,19 @@
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"
static textwindows int64_t open$nt$impl(const char *file, uint32_t flags,
int32_t mode) {
static textwindows int64_t open$nt$impl(int dirfd, const char *path,
uint32_t flags, int32_t mode) {
uint32_t br;
int64_t handle;
char16_t file16[PATH_MAX];
if (__mkntpath2(file, file16, flags) == -1) return -1;
char16_t path16[PATH_MAX];
if (__mkntpathat(dirfd, path, flags, path16) == -1) return -1;
if ((handle = CreateFile(
file16,
path16,
(flags & 0xf000000f) |
(/* this is needed if we mmap(rwx+cow)
nt is choosy about open() access */
@ -82,11 +83,18 @@ static textwindows int64_t open$nt$impl(const char *file, uint32_t flags,
*/
DeviceIoControl(handle, kNtFsctlSetSparse, NULL, 0, NULL, 0, &br, NULL);
}
return handle;
} else if (GetLastError() == kNtErrorFileExists &&
((flags & O_CREAT) &&
(flags & O_TRUNC))) { /* TODO(jart): What was this? */
return eisdir();
} else {
return __winerr();
}
return handle;
}
static textwindows ssize_t open$nt$console(const struct NtMagicPaths *mp,
static textwindows ssize_t open$nt$console(int dirfd,
const struct NtMagicPaths *mp,
uint32_t flags, int32_t mode,
size_t fd) {
if (GetFileType(g_fds.p[STDIN_FILENO].handle) == kNtFileTypeChar &&
@ -94,39 +102,38 @@ static textwindows ssize_t open$nt$console(const struct NtMagicPaths *mp,
g_fds.p[fd].handle = g_fds.p[STDIN_FILENO].handle;
g_fds.p[fd].extra = g_fds.p[STDOUT_FILENO].handle;
} else if ((g_fds.p[fd].handle = open$nt$impl(
mp->conin, (flags & ~O_ACCMODE) | O_RDONLY, mode)) != -1) {
dirfd, mp->conin, (flags & ~O_ACCMODE) | O_RDONLY, mode)) !=
-1) {
g_fds.p[fd].extra =
open$nt$impl(mp->conout, (flags & ~O_ACCMODE) | O_WRONLY, mode);
open$nt$impl(dirfd, mp->conout, (flags & ~O_ACCMODE) | O_WRONLY, mode);
assert(g_fds.p[fd].extra != -1);
} else {
return __winerr();
return -1;
}
g_fds.p[fd].kind = kFdConsole;
g_fds.p[fd].flags = flags;
return fd;
}
static textwindows ssize_t open$nt$file(const char *file, uint32_t flags,
int32_t mode, size_t fd) {
if ((g_fds.p[fd].handle = open$nt$impl(file, flags, mode)) != -1) {
static textwindows ssize_t open$nt$file(int dirfd, const char *file,
uint32_t flags, int32_t mode,
size_t fd) {
if ((g_fds.p[fd].handle = open$nt$impl(dirfd, file, flags, mode)) != -1) {
g_fds.p[fd].kind = kFdFile;
g_fds.p[fd].flags = flags;
return fd;
} else if (GetLastError() == kNtErrorFileExists &&
((flags & O_CREAT) && (flags & O_TRUNC))) {
return eisdir();
} else {
return __winerr();
return -1;
}
}
textwindows ssize_t open$nt(const char *file, uint32_t flags, int32_t mode) {
textwindows ssize_t open$nt(int dirfd, const char *file, uint32_t flags,
int32_t mode) {
size_t fd;
if ((fd = __getemptyfd()) == -1) return -1;
if ((flags & O_ACCMODE) == O_RDWR &&
strcmp(file, kNtMagicPaths.devtty) == 0) {
return open$nt$console(&kNtMagicPaths, flags, mode, fd);
if ((flags & O_ACCMODE) == O_RDWR && !strcmp(file, kNtMagicPaths.devtty)) {
return open$nt$console(dirfd, &kNtMagicPaths, flags, mode, fd);
} else {
return open$nt$file(file, flags, mode, fd);
return open$nt$file(dirfd, file, flags, mode, fd);
}
}