summaryrefslogtreecommitdiffstats
path: root/applypatch/freecache.cpp
blob: 331cae265feea23c08523d98c71e8abf9ffa2224 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
/*
 * Copyright (C) 2010 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.
 */

#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <unistd.h>
#include <dirent.h>
#include <ctype.h>

#include <memory>
#include <set>
#include <string>

#include <android-base/parseint.h>
#include <android-base/stringprintf.h>

#include "applypatch/applypatch.h"

static int EliminateOpenFiles(std::set<std::string>* files) {
  std::unique_ptr<DIR, decltype(&closedir)> d(opendir("/proc"), closedir);
  if (!d) {
    printf("error opening /proc: %s\n", strerror(errno));
    return -1;
  }
  struct dirent* de;
  while ((de = readdir(d.get())) != 0) {
    unsigned int pid;
    if (!android::base::ParseUint(de->d_name, &pid)) {
        continue;
    }
    std::string path = android::base::StringPrintf("/proc/%s/fd/", de->d_name);

    struct dirent* fdde;
    std::unique_ptr<DIR, decltype(&closedir)> fdd(opendir(path.c_str()), closedir);
    if (!fdd) {
      printf("error opening %s: %s\n", path.c_str(), strerror(errno));
      continue;
    }
    while ((fdde = readdir(fdd.get())) != 0) {
      std::string fd_path = path + fdde->d_name;
      char link[FILENAME_MAX];

      int count = readlink(fd_path.c_str(), link, sizeof(link)-1);
      if (count >= 0) {
        link[count] = '\0';
        if (strncmp(link, "/cache/", 7) == 0) {
          if (files->erase(link) > 0) {
            printf("%s is open by %s\n", link, de->d_name);
          }
        }
      }
    }
  }
  return 0;
}

static std::set<std::string> FindExpendableFiles() {
  std::set<std::string> files;
  // We're allowed to delete unopened regular files in any of these
  // directories.
  const char* dirs[2] = {"/cache", "/cache/recovery/otatest"};

  for (size_t i = 0; i < sizeof(dirs)/sizeof(dirs[0]); ++i) {
    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(dirs[i]), closedir);
    if (!d) {
      printf("error opening %s: %s\n", dirs[i], strerror(errno));
      continue;
    }

    // Look for regular files in the directory (not in any subdirectories).
    struct dirent* de;
    while ((de = readdir(d.get())) != 0) {
      std::string path = std::string(dirs[i]) + "/" + de->d_name;

      // We can't delete CACHE_TEMP_SOURCE; if it's there we might have
      // restarted during installation and could be depending on it to
      // be there.
      if (path == CACHE_TEMP_SOURCE) {
        continue;
      }

      struct stat st;
      if (stat(path.c_str(), &st) == 0 && S_ISREG(st.st_mode)) {
        files.insert(path);
      }
    }
  }

  printf("%zu regular files in deletable directories\n", files.size());
  if (EliminateOpenFiles(&files) < 0) {
    return std::set<std::string>();
  }
  return files;
}

int MakeFreeSpaceOnCache(size_t bytes_needed) {
  size_t free_now = FreeSpaceForFile("/cache");
  printf("%zu bytes free on /cache (%zu needed)\n", free_now, bytes_needed);

  if (free_now >= bytes_needed) {
    return 0;
  }
  std::set<std::string> files = FindExpendableFiles();
  if (files.empty()) {
    // nothing we can delete to free up space!
    printf("no files can be deleted to free space on /cache\n");
    return -1;
  }

  // We could try to be smarter about which files to delete:  the
  // biggest ones?  the smallest ones that will free up enough space?
  // the oldest?  the newest?
  //
  // Instead, we'll be dumb.

  for (const auto& file : files) {
    unlink(file.c_str());
    free_now = FreeSpaceForFile("/cache");
    printf("deleted %s; now %zu bytes free\n", file.c_str(), free_now);
    if (free_now < bytes_needed) {
        break;
    }
  }
  return (free_now >= bytes_needed) ? 0 : -1;
}