1 /*
2 * Copyright (C) 2010 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 <errno.h>
18 #include <libgen.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <sys/stat.h>
23 #include <sys/statfs.h>
24 #include <unistd.h>
25 #include <dirent.h>
26 #include <ctype.h>
27
28 #include <memory>
29 #include <set>
30 #include <string>
31
32 #include <android-base/parseint.h>
33 #include <android-base/stringprintf.h>
34
35 #include "applypatch/applypatch.h"
36
EliminateOpenFiles(std::set<std::string> * files)37 static int EliminateOpenFiles(std::set<std::string>* files) {
38 std::unique_ptr<DIR, decltype(&closedir)> d(opendir("/proc"), closedir);
39 if (!d) {
40 printf("error opening /proc: %s\n", strerror(errno));
41 return -1;
42 }
43 struct dirent* de;
44 while ((de = readdir(d.get())) != 0) {
45 unsigned int pid;
46 if (!android::base::ParseUint(de->d_name, &pid)) {
47 continue;
48 }
49 std::string path = android::base::StringPrintf("/proc/%s/fd/", de->d_name);
50
51 struct dirent* fdde;
52 std::unique_ptr<DIR, decltype(&closedir)> fdd(opendir(path.c_str()), closedir);
53 if (!fdd) {
54 printf("error opening %s: %s\n", path.c_str(), strerror(errno));
55 continue;
56 }
57 while ((fdde = readdir(fdd.get())) != 0) {
58 std::string fd_path = path + fdde->d_name;
59 char link[FILENAME_MAX];
60
61 int count = readlink(fd_path.c_str(), link, sizeof(link)-1);
62 if (count >= 0) {
63 link[count] = '\0';
64 if (strncmp(link, "/cache/", 7) == 0) {
65 if (files->erase(link) > 0) {
66 printf("%s is open by %s\n", link, de->d_name);
67 }
68 }
69 }
70 }
71 }
72 return 0;
73 }
74
FindExpendableFiles()75 static std::set<std::string> FindExpendableFiles() {
76 std::set<std::string> files;
77 // We're allowed to delete unopened regular files in any of these
78 // directories.
79 const char* dirs[2] = {"/cache", "/cache/recovery/otatest"};
80
81 for (size_t i = 0; i < sizeof(dirs)/sizeof(dirs[0]); ++i) {
82 std::unique_ptr<DIR, decltype(&closedir)> d(opendir(dirs[i]), closedir);
83 if (!d) {
84 printf("error opening %s: %s\n", dirs[i], strerror(errno));
85 continue;
86 }
87
88 // Look for regular files in the directory (not in any subdirectories).
89 struct dirent* de;
90 while ((de = readdir(d.get())) != 0) {
91 std::string path = std::string(dirs[i]) + "/" + de->d_name;
92
93 // We can't delete CACHE_TEMP_SOURCE; if it's there we might have
94 // restarted during installation and could be depending on it to
95 // be there.
96 if (path == CACHE_TEMP_SOURCE) {
97 continue;
98 }
99
100 struct stat st;
101 if (stat(path.c_str(), &st) == 0 && S_ISREG(st.st_mode)) {
102 files.insert(path);
103 }
104 }
105 }
106
107 printf("%zu regular files in deletable directories\n", files.size());
108 if (EliminateOpenFiles(&files) < 0) {
109 return std::set<std::string>();
110 }
111 return files;
112 }
113
MakeFreeSpaceOnCache(size_t bytes_needed)114 int MakeFreeSpaceOnCache(size_t bytes_needed) {
115 size_t free_now = FreeSpaceForFile("/cache");
116 printf("%zu bytes free on /cache (%zu needed)\n", free_now, bytes_needed);
117
118 if (free_now >= bytes_needed) {
119 return 0;
120 }
121 std::set<std::string> files = FindExpendableFiles();
122 if (files.empty()) {
123 // nothing we can delete to free up space!
124 printf("no files can be deleted to free space on /cache\n");
125 return -1;
126 }
127
128 // We could try to be smarter about which files to delete: the
129 // biggest ones? the smallest ones that will free up enough space?
130 // the oldest? the newest?
131 //
132 // Instead, we'll be dumb.
133
134 for (const auto& file : files) {
135 unlink(file.c_str());
136 free_now = FreeSpaceForFile("/cache");
137 printf("deleted %s; now %zu bytes free\n", file.c_str(), free_now);
138 if (free_now < bytes_needed) {
139 break;
140 }
141 }
142 return (free_now >= bytes_needed) ? 0 : -1;
143 }
144