libs/androidfw/misc.cpp

/*
 * Copyright (C) 2005 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "misc"

#include "androidfw/misc.h"

#include <errno.h>
#include <sys/stat.h>

#include "android-base/logging.h"

#ifdef __linux__
#include <sys/statvfs.h>
#include <sys/vfs.h>
#endif  // __linux__

#include <array>
#include <cstdio>
#include <cstring>

namespace android {

/*
 * Get a file's type.
 */
FileType getFileType(const char* fileName) {
  struct stat sb;
  if (stat(fileName, &sb) < 0) {
    if (errno == ENOENT || errno == ENOTDIR)
      return kFileTypeNonexistent;
    else {
      PLOG(ERROR) << "getFileType(): stat(" << fileName << ") failed";
      return kFileTypeUnknown;
    }
  } else {
    if (S_ISREG(sb.st_mode))
      return kFileTypeRegular;
    else if (S_ISDIR(sb.st_mode))
      return kFileTypeDirectory;
    else if (S_ISCHR(sb.st_mode))
      return kFileTypeCharDev;
    else if (S_ISBLK(sb.st_mode))
      return kFileTypeBlockDev;
    else if (S_ISFIFO(sb.st_mode))
      return kFileTypeFifo;
#if defined(S_ISLNK)
        else if (S_ISLNK(sb.st_mode))
            return kFileTypeSymlink;
#endif
#if defined(S_ISSOCK)
        else if (S_ISSOCK(sb.st_mode))
            return kFileTypeSocket;
#endif
        else
            return kFileTypeUnknown;
    }
}

ModDate getModDate(const struct stat& st) {
#ifdef _WIN32
  return st.st_mtime;
#elif defined(__APPLE__)
  return st.st_mtimespec;
#else
  return st.st_mtim;
#endif
}

ModDate getFileModDate(const char* fileName) {
  struct stat sb;
  if (stat(fileName, &sb) < 0) {
    return kInvalidModDate;
  }
  return getModDate(sb);
}

ModDate getFileModDate(int fd) {
  struct stat sb;
  if (fstat(fd, &sb) < 0) {
    return kInvalidModDate;
  }
  if (sb.st_nlink <= 0) {
    errno = ENOENT;
    return kInvalidModDate;
  }
  return getModDate(sb);
}

#ifndef __linux__
// No need to implement these on the host, the functions only matter on a device.
bool isReadonlyFilesystem(const char*) {
    return false;
}
bool isReadonlyFilesystem(int) {
    return false;
}
bool isKnownWritablePath(const char*) {
  return false;
}
#else   // __linux__
bool isReadonlyFilesystem(const char* path) {
  if (isKnownWritablePath(path)) {
    return false;
  }
    struct statfs sfs;
    if (::statfs(path, &sfs)) {
        PLOG(ERROR) << "isReadonlyFilesystem(): statfs(" << path << ") failed";
        return false;
    }
    return (sfs.f_flags & ST_RDONLY) != 0;
}

bool isReadonlyFilesystem(int fd) {
    struct statfs sfs;
    if (::fstatfs(fd, &sfs)) {
        PLOG(ERROR) << "isReadonlyFilesystem(): fstatfs(" << fd << ") failed";
        return false;
    }
    return (sfs.f_flags & ST_RDONLY) != 0;
}

bool isKnownWritablePath(const char* path) {
  // We know that all paths in /data/ are writable.
  static constexpr char kRwPrefix[] = "/data/";
  return strncmp(kRwPrefix, path, std::size(kRwPrefix) - 1) == 0;
}

#endif  // __linux__

}  // namespace android