upload android base code part3

android/bootable/recovery/applypatch/freecache.cpp

@@ -0,0 +1,143 @@
+/*
+ * 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;
+}