cosmopolitan/libc/calls/open-nt.c
Justine Tunney 2db2f40a98
Rewrite special file handling on Windows
This change gets GNU grep working. What caused it to not work, is it
wouldn't write to an output file descriptor when its dev/ino equaled
/dev/null's. So now we invent special dev/ino values for these files
2023-10-14 02:53:34 -07:00

215 lines
8.6 KiB
C

/*-*- 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/assert.h"
#include "libc/calls/internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/errno.h"
#include "libc/macros.internal.h"
#include "libc/nt/console.h"
#include "libc/nt/createfile.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/creationdisposition.h"
#include "libc/nt/enum/fileflagandattributes.h"
#include "libc/nt/enum/filesharemode.h"
#include "libc/nt/enum/filetype.h"
#include "libc/nt/files.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/synchronization.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"
__msabi extern typeof(GetFileAttributes) *const __imp_GetFileAttributesW;
static textwindows int64_t sys_open_nt_impl(int dirfd, const char *path,
uint32_t flags, int32_t mode,
uint32_t extra_attr) {
// join(topath(dirfd), path) and translate from utf-8 to utf-16
char16_t path16[PATH_MAX];
if (__mkntpathat(dirfd, path, flags, path16) == -1) {
return kNtInvalidHandleValue;
}
// implement no follow flag
// you can't open symlinks; use readlink
// this flag only applies to the final path component
// if O_NOFOLLOW_ANY is passed (-1 on NT) it'll be rejected later
uint32_t fattr = GetFileAttributes(path16);
if (flags & O_NOFOLLOW) {
if (fattr != -1u && (fattr & kNtFileAttributeReparsePoint)) {
return eloop();
}
flags &= ~O_NOFOLLOW; // don't actually pass this to win32
}
// handle some obvious cases while we have the attributes
// we should ideally resolve symlinks ourself before doing this
if (fattr != -1u) {
if (fattr & kNtFileAttributeDirectory) {
if ((flags & O_ACCMODE) != O_RDONLY || (flags & O_CREAT)) {
// tried to open directory for writing. note that our
// undocumented O_TMPFILE support on windows requires that a
// filename be passed, rather than a directory like linux.
return eisdir();
}
// on posix, the o_directory flag is an advisory safeguard that
// isn't required. on windows, it's mandatory for opening a dir
flags |= O_DIRECTORY;
} else if (!(fattr & kNtFileAttributeReparsePoint)) {
// we know for certain file isn't a directory
if (flags & O_DIRECTORY) {
return enotdir();
}
}
}
// translate posix flags to win32 flags
uint32_t perm, share, disp, attr;
if (GetNtOpenFlags(flags, mode, &perm, &share, &disp, &attr) == -1) {
return kNtInvalidHandleValue;
}
if (fattr != -1u) {
// "We have been asked to create a read-only file. "If the file
// already exists, the semantics of the Unix open system call is to
// preserve the existing permissions. If we pass CREATE_ALWAYS and
// FILE_ATTRIBUTE_READONLY to CreateFile, and the file already
// exists, CreateFile will change the file permissions. Avoid that to
// preserve the Unix semantics." -Quoth GoLang syscall_windows.go
attr &= ~kNtFileAttributeReadonly;
}
// kNtTruncateExisting always returns kNtErrorInvalidParameter :'(
if (disp == kNtTruncateExisting) {
if (fattr != -1u) {
disp = kNtCreateAlways; // file exists (wish it could be more atomic)
} else {
return __fix_enotdir(enotdir(), path16);
}
}
// We optimistically request some write permissions in O_RDONLY mode.
// But that might prevent opening some files. So reactively back off.
int extra_perm = 0;
if ((flags & O_ACCMODE) == O_RDONLY) {
extra_perm = kNtFileWriteAttributes | kNtFileWriteEa;
}
// open the file, following symlinks
int e = errno;
int64_t hand = CreateFile(path16, perm | extra_perm, share, &kNtIsInheritable,
disp, attr | extra_attr, 0);
if (hand == -1 && errno == EACCES && (flags & O_ACCMODE) == O_RDONLY) {
errno = e;
hand = CreateFile(path16, perm, share, &kNtIsInheritable, disp,
attr | extra_attr, 0);
}
return __fix_enotdir(hand, path16);
}
static textwindows int sys_open_nt_file(int dirfd, const char *file,
uint32_t flags, int32_t mode,
size_t fd) {
int64_t handle;
if ((handle = sys_open_nt_impl(dirfd, file, flags, mode,
kNtFileFlagOverlapped)) != -1) {
g_fds.p[fd].handle = handle;
g_fds.p[fd].kind = kFdFile;
g_fds.p[fd].flags = flags;
g_fds.p[fd].mode = mode;
return fd;
} else {
return -1;
}
}
static textwindows int sys_open_nt_special(int fd, int flags, int mode,
int kind, const char16_t *name) {
g_fds.p[fd].kind = kind;
g_fds.p[fd].mode = mode;
g_fds.p[fd].flags = flags;
g_fds.p[fd].handle = CreateFile(name, kNtGenericRead | kNtGenericWrite,
kNtFileShareRead | kNtFileShareWrite,
&kNtIsInheritable, kNtOpenExisting, 0, 0);
return fd;
}
static textwindows int sys_open_nt_dup(int fd, int flags, int mode, int oldfd) {
int64_t handle;
if (!__isfdopen(oldfd)) {
return enoent();
}
if (DuplicateHandle(GetCurrentProcess(), g_fds.p[oldfd].handle,
GetCurrentProcess(), &handle, 0, true,
kNtDuplicateSameAccess)) {
g_fds.p[fd] = g_fds.p[oldfd];
g_fds.p[fd].handle = handle;
g_fds.p[fd].mode = mode;
if (!sys_fcntl_nt_setfl(fd, flags)) {
return fd;
} else {
CloseHandle(handle);
return -1;
}
} else {
return __winerr();
}
}
textwindows int sys_open_nt(int dirfd, const char *file, uint32_t flags,
int32_t mode) {
int fd;
ssize_t rc;
BLOCK_SIGNALS;
__fds_lock();
if (!(flags & O_CREAT)) mode = 0;
if ((rc = fd = __reservefd_unlocked(-1)) != -1) {
if (startswith(file, "/dev/")) {
if (!strcmp(file + 5, "tty")) {
rc = sys_open_nt_special(fd, flags, mode, kFdConsole, u"CONIN$");
} else if (!strcmp(file + 5, "null")) {
rc = sys_open_nt_special(fd, flags, mode, kFdDevNull, u"NUL");
} else if (!strcmp(file + 5, "stdin")) {
rc = sys_open_nt_dup(fd, flags, mode, STDIN_FILENO);
} else if (!strcmp(file + 5, "stdout")) {
rc = sys_open_nt_dup(fd, flags, mode, STDOUT_FILENO);
} else if (!strcmp(file + 5, "stderr")) {
rc = sys_open_nt_dup(fd, flags, mode, STDERR_FILENO);
} else {
rc = enoent();
}
} else {
rc = sys_open_nt_file(dirfd, file, flags, mode, fd);
}
if (rc == -1) {
__releasefd(fd);
}
__fds_unlock();
}
ALLOW_SIGNALS;
return rc;
}