1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "android-base/file.h"
18
19#include <errno.h>
20#include <fcntl.h>
21#include <sys/stat.h>
22#include <sys/types.h>
23
24#include <string>
25
26#include "android-base/macros.h"  // For TEMP_FAILURE_RETRY on Darwin.
27#include "android-base/utf8.h"
28#define LOG_TAG "base.file"
29#include "cutils/log.h"
30#include "utils/Compat.h"
31
32namespace android {
33namespace base {
34
35// Versions of standard library APIs that support UTF-8 strings.
36using namespace android::base::utf8;
37
38bool ReadFdToString(int fd, std::string* content) {
39  content->clear();
40
41  char buf[BUFSIZ];
42  ssize_t n;
43  while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) {
44    content->append(buf, n);
45  }
46  return (n == 0) ? true : false;
47}
48
49bool ReadFileToString(const std::string& path, std::string* content) {
50  content->clear();
51
52  int fd = TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW | O_BINARY));
53  if (fd == -1) {
54    return false;
55  }
56  bool result = ReadFdToString(fd, content);
57  close(fd);
58  return result;
59}
60
61bool WriteStringToFd(const std::string& content, int fd) {
62  const char* p = content.data();
63  size_t left = content.size();
64  while (left > 0) {
65    ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left));
66    if (n == -1) {
67      return false;
68    }
69    p += n;
70    left -= n;
71  }
72  return true;
73}
74
75static bool CleanUpAfterFailedWrite(const std::string& path) {
76  // Something went wrong. Let's not leave a corrupt file lying around.
77  int saved_errno = errno;
78  unlink(path.c_str());
79  errno = saved_errno;
80  return false;
81}
82
83#if !defined(_WIN32)
84bool WriteStringToFile(const std::string& content, const std::string& path,
85                       mode_t mode, uid_t owner, gid_t group) {
86  int flags = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW | O_BINARY;
87  int fd = TEMP_FAILURE_RETRY(open(path.c_str(), flags, mode));
88  if (fd == -1) {
89    ALOGE("android::WriteStringToFile open failed: %s", strerror(errno));
90    return false;
91  }
92
93  // We do an explicit fchmod here because we assume that the caller really
94  // meant what they said and doesn't want the umask-influenced mode.
95  if (fchmod(fd, mode) == -1) {
96    ALOGE("android::WriteStringToFile fchmod failed: %s", strerror(errno));
97    return CleanUpAfterFailedWrite(path);
98  }
99  if (fchown(fd, owner, group) == -1) {
100    ALOGE("android::WriteStringToFile fchown failed: %s", strerror(errno));
101    return CleanUpAfterFailedWrite(path);
102  }
103  if (!WriteStringToFd(content, fd)) {
104    ALOGE("android::WriteStringToFile write failed: %s", strerror(errno));
105    return CleanUpAfterFailedWrite(path);
106  }
107  close(fd);
108  return true;
109}
110#endif
111
112bool WriteStringToFile(const std::string& content, const std::string& path) {
113  int flags = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW | O_BINARY;
114  int fd = TEMP_FAILURE_RETRY(open(path.c_str(), flags, DEFFILEMODE));
115  if (fd == -1) {
116    return false;
117  }
118
119  bool result = WriteStringToFd(content, fd);
120  close(fd);
121  return result || CleanUpAfterFailedWrite(path);
122}
123
124bool ReadFully(int fd, void* data, size_t byte_count) {
125  uint8_t* p = reinterpret_cast<uint8_t*>(data);
126  size_t remaining = byte_count;
127  while (remaining > 0) {
128    ssize_t n = TEMP_FAILURE_RETRY(read(fd, p, remaining));
129    if (n <= 0) return false;
130    p += n;
131    remaining -= n;
132  }
133  return true;
134}
135
136bool WriteFully(int fd, const void* data, size_t byte_count) {
137  const uint8_t* p = reinterpret_cast<const uint8_t*>(data);
138  size_t remaining = byte_count;
139  while (remaining > 0) {
140    ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, remaining));
141    if (n == -1) return false;
142    p += n;
143    remaining -= n;
144  }
145  return true;
146}
147
148bool RemoveFileIfExists(const std::string& path, std::string* err) {
149  struct stat st;
150#if defined(_WIN32)
151  //TODO: Windows version can't handle symbol link correctly.
152  int result = stat(path.c_str(), &st);
153  bool file_type_removable = (result == 0 && S_ISREG(st.st_mode));
154#else
155  int result = lstat(path.c_str(), &st);
156  bool file_type_removable = (result == 0 && (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)));
157#endif
158  if (result == 0) {
159    if (!file_type_removable) {
160      if (err != nullptr) {
161        *err = "is not a regular or symbol link file";
162      }
163      return false;
164    }
165    if (unlink(path.c_str()) == -1) {
166      if (err != nullptr) {
167        *err = strerror(errno);
168      }
169      return false;
170    }
171  }
172  return true;
173}
174
175}  // namespace base
176}  // namespace android
177