cosmopolitan/libc/calls/mkntpathat.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 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/calls/syscall_support-nt.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/strace.h"
#include "libc/macros.h"
#include "libc/nt/enum/fileflagandattributes.h"
#include "libc/nt/files.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/errfuns.h"

static int IsAlpha(int c) {
  return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}

static bool IsAbsolutePathWin32(char16_t *path) {
  if (path[0] == '\\')
    return true;
  if (IsAlpha(path[0]) && path[1] == ':')
    return true;
  return false;
}

static textwindows int __mkntpathath_impl(int64_t dirhand, const char *path,
                                          int flags,
                                          char16_t file[hasatleast PATH_MAX]) {
  size_t n;
  char16_t dir[PATH_MAX];
  uint32_t dirlen, filelen;
  if (!isutf8(path, -1))
    return eilseq();  // thwart overlong nul in conversion
  if ((filelen = __mkntpath2(path, file, flags)) == -1)
    return -1;
  if (!filelen)
    return enoent();
  if (dirhand != AT_FDCWD && !IsAbsolutePathWin32(file)) {
    dirlen = GetFinalPathNameByHandle(dirhand, dir, ARRAYLEN(dir),
                                      kNtFileNameNormalized | kNtVolumeNameDos);
    if (!dirlen)
      return __winerr();
    if (dirlen + 1 + filelen + 1 > ARRAYLEN(dir))
      return enametoolong();
    dir[dirlen] = u'\\';
    memcpy(dir + dirlen + 1, file, (filelen + 1) * sizeof(char16_t));
    memcpy(file, dir, ((n = dirlen + 1 + filelen) + 1) * sizeof(char16_t));
    n = __normntpath(file, n);

    // UNC paths break some things when they are not needed.
    if (n > 4 && n < 260 &&  //
        file[0] == '\\' &&   //
        file[1] == '\\' &&   //
        file[2] == '?' &&    //
        file[3] == '\\') {
      memmove(file, file + 4, (n - 4 + 1) * sizeof(char16_t));
    }

    return n;
  } else {
    return filelen;
  }
}

textwindows int __mkntpathath(int64_t dirhand, const char *path, int flags,
                              char16_t file[hasatleast PATH_MAX]) {

  // convert the path.
  int len;
  if ((len = __mkntpathath_impl(dirhand, path, flags, file)) == -1) {
    return -1;
  }

  // if path ends with a slash, then we need to manually do what linux
  // does and check to make sure it's a directory, and return ENOTDIR,
  // since WIN32 will reject the path with EINVAL if we don't do this.
  if (len && file[len - 1] == '\\') {
    uint32_t fattr;
    if (len > 1 && !(len == 3 && file[1] == ':')) {
      file[--len] = 0;
    }
    if ((fattr = GetFileAttributes(file)) != -1u &&
        !(fattr & kNtFileAttributeReparsePoint) &&
        !(fattr & kNtFileAttributeDirectory)) {
      return enotdir();
    }
  }

  return len;
}

textwindows int __mkntpathat(int dirfd, const char *path, int flags,
                             char16_t file[hasatleast PATH_MAX]) {
  int64_t dirhand;
  if (dirfd == AT_FDCWD) {
    dirhand = AT_FDCWD;
  } else if (__isfdkind(dirfd, kFdFile)) {
    dirhand = g_fds.p[dirfd].handle;
  } else {
    return ebadf();
  }
  return __mkntpathath(dirhand, path, flags, file);
}