cosmopolitan/libc/calls/mkntpath.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

198 lines
6.6 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/calls/syscall_support-nt.internal.h"
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/strace.internal.h"
#include "libc/macros.internal.h"
#include "libc/nt/systeminfo.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"
static inline bool IsSlash(char c) {
return c == '/' || c == '\\';
}
static inline int IsAlpha(int c) {
return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}
textwindows size_t __normntpath(char16_t *p, size_t n) {
size_t i, j;
for (j = i = 0; i < n; ++i) {
int c = p[i];
if (c == '/') {
c = '\\';
}
if (j > 1 && c == '\\' && p[j - 1] == '\\') {
// matched "^/" or "//" but not "^//"
} else if ((j && p[j - 1] == '\\') && //
c == '.' && //
(i + 1 == n || IsSlash(p[i + 1]))) {
// matched "/./" or "/.$"
i += !(i + 1 == n);
} else if ((j && p[j - 1] == '\\') && //
c == '.' && //
(i + 1 < n && p[i + 1] == '.') && //
(i + 2 == n || IsSlash(p[i + 2]))) {
// matched "/../" or "/..$"
while (j && p[j - 1] == '\\') --j;
while (j && p[j - 1] != '\\') --j;
} else {
p[j++] = c;
}
}
p[j] = 0;
return j;
}
textwindows int __mkntpath(const char *path,
char16_t path16[hasatleast PATH_MAX]) {
return __mkntpath2(path, path16, -1);
}
/**
* Copies path for Windows NT.
*
* This function does the following chores:
*
* 1. Converting UTF-8 to UTF-16
* 2. Replacing forward-slashes with backslashes
* 3. Fixing drive letter paths, e.g. `/c/` → `c:\`
* 4. Add `\\?\` prefix for paths exceeding 260 chars
* 5. Remapping well-known paths, e.g. `/dev/null` → `NUL`
*
* @param flags is used by open()
* @param path16 is shortened so caller can prefix, e.g. \\.\pipe\, and
* due to a plethora of special-cases throughout the Win32 API
* @return short count excluding NUL on success, or -1 w/ errno
* @error ENAMETOOLONG
*/
textwindows int __mkntpath2(const char *path,
char16_t path16[hasatleast PATH_MAX], int flags) {
// 1. Need +1 for NUL-terminator
// 2. Need +1 for UTF-16 overflow
// 3. Need ≥2 for SetCurrentDirectory trailing slash requirement
// 4. Need ≥13 for mkdir() i.e. 1+8+3+1, e.g. "\\ffffffff.xxx\0"
// which is an "8.3 filename" from the DOS days
if (!path || (IsAsan() && !__asan_is_valid_str(path))) {
return efault();
}
size_t x, z;
char16_t *p = path16;
const char *q = path;
if (IsSlash(q[0]) && IsAlpha(q[1]) && IsSlash(q[2])) {
z = MIN(32767, PATH_MAX);
// turn "\c\foo" into "\\?\c:\foo"
p[0] = '\\';
p[1] = '\\';
p[2] = '?';
p[3] = '\\';
p[4] = q[1];
p[5] = ':';
p[6] = '\\';
p += 7;
q += 3;
z -= 7;
x = 7;
} else if (IsSlash(q[0]) && IsAlpha(q[1]) && !q[2]) {
z = MIN(32767, PATH_MAX);
// turn "\c" into "\\?\c:\"
p[0] = '\\';
p[1] = '\\';
p[2] = '?';
p[3] = '\\';
p[4] = q[1];
p[5] = ':';
p[6] = '\\';
p += 7;
q += 2;
z -= 7;
x = 7;
} else if (IsAlpha(q[0]) && q[1] == ':' && IsSlash(q[2])) {
z = MIN(32767, PATH_MAX);
// turn "c:\foo" into "\\?\c:\foo"
p[0] = '\\';
p[1] = '\\';
p[2] = '?';
p[3] = '\\';
p[4] = q[0];
p[5] = ':';
p[6] = '\\';
p += 7;
q += 3;
z -= 7;
x = 7;
} else if (IsSlash(q[0]) && IsSlash(q[1]) && q[2] == '?' && IsSlash(q[3])) {
z = MIN(32767, PATH_MAX);
x = 0;
} else {
z = MIN(260, PATH_MAX);
x = 0;
}
// turn /tmp into GetTempPath()
size_t m;
if (!x && IsSlash(q[0]) && q[1] == 't' && q[2] == 'm' && q[3] == 'p' &&
(IsSlash(q[4]) || !q[4])) {
m = GetTempPath(z, p);
if (!q[4]) return m;
q += 5;
p += m;
z -= m;
} else {
m = 0;
}
// turn utf-8 into utf-16
size_t n = tprecode8to16(p, z, q).ax;
if (n >= z - 1) {
return enametoolong();
}
// normalize path
// we need it because \\?\... paths have to be normalized
// we don't remove the trailing slash since it is special
n = __normntpath(p, n);
// our path is now stored at `path16` with length `n`
n = x + m + n;
// To avoid toil like this:
//
// "CMD.EXE was started with the above path as the current
// directory. UNC paths are not supported. Defaulting to Windows
// directory. Access is denied." -Quoth CMD.EXE
//
// Remove \\?\ prefix if we're within the 260 character limit.
if (n > 4 && n < 260 && //
path16[0] == '\\' && //
path16[1] == '\\' && //
path16[2] == '?' && //
path16[3] == '\\') {
memmove(path16, path16 + 4, (n - 4 + 1) * sizeof(char16_t));
n -= 4;
}
return n;
}