/*
* Copyright (C) 2008 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 "private/android_filesystem_config.h"
#include <dirent.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
/*
* Recursively walk the directory tree at <sysdir>/<subdir>, writing
* script commands to set permissions and create symlinks.
* Assume the contents already have the specified default permissions,
* so only output commands if they need to be changed from the defaults.
*
* Note that permissions are set by fs_config(), which uses a lookup table of
* Android permissions. They are not drawn from the build host filesystem.
*/
static void walk_files(
const char *sysdir, const char *subdir,
unsigned default_uid, unsigned default_gid,
unsigned default_dir_mode, unsigned default_file_mode) {
const char *sep = strcmp(subdir, "") ? "/" : "";
char fn[PATH_MAX];
unsigned dir_uid = 0, dir_gid = 0, dir_mode = 0;
snprintf(fn, PATH_MAX, "system%s%s", sep, subdir);
fs_config(fn, 1, &dir_uid, &dir_gid, &dir_mode);
snprintf(fn, PATH_MAX, "%s%s%s", sysdir, sep, subdir);
DIR *dir = opendir(fn);
if (dir == NULL) {
perror(fn);
exit(1);
}
/*
* We can use "set_perm" and "set_perm_recursive" to set file permissions
* (owner, group, and file mode) for individual files and entire subtrees.
* We want to use set_perm_recursive efficiently to avoid setting the
* permissions of every single file in the system image individually.
*
* What we do is recursively set our entire subtree to the permissions
* used by the first file we encounter, and then use "set_perm" to adjust
* the permissions of subsequent files which don't match the first one.
* This is bad if the first file is an outlier, but it generally works.
* Subdirectories can do the same thing recursively if they're different.
*/
int is_first = 1;
const struct dirent *e;
while ((e = readdir(dir))) {
// Skip over "." and ".." entries
if (!strcmp(e->d_name, ".") || !strcmp(e->d_name, "..")) continue;
if (e->d_type == DT_LNK) { // Symlink
// Symlinks don't really have permissions, so this is orthogonal.
snprintf(fn, PATH_MAX, "%s/%s%s%s", sysdir, subdir, sep, e->d_name);
int len = readlink(fn, fn, PATH_MAX - 1);
if (len <= 0) {
perror(fn);
exit(1);
}
fn[len] = '\0';
printf("symlink %s SYSTEM:%s%s%s\n", fn, subdir, sep, e->d_name);
} else if (e->d_type == DT_DIR) { // Subdirectory
// Use the parent directory as the model for default permissions.
// We haven't seen a file, so just make up some file defaults.
if (is_first && (
dir_mode != default_dir_mode ||
dir_uid != default_uid || dir_gid != default_gid)) {
default_uid = dir_uid;
default_gid = dir_gid;
default_dir_mode = dir_mode;
default_file_mode = dir_mode & default_file_mode & 0666;
printf("set_perm_recursive %d %d 0%o 0%o SYSTEM:%s\n",
default_uid, default_gid,
default_dir_mode, default_file_mode,
subdir);
}
is_first = 0;
// Recursively handle the subdirectory.
// Note, the recursive call handles the directory's own permissions.
snprintf(fn, PATH_MAX, "%s%s%s", subdir, sep, e->d_name);
walk_files(sysdir, fn,
default_uid, default_gid,
default_dir_mode, default_file_mode);
} else { // Ordinary file
// Get the file's desired permissions.
unsigned file_uid = 0, file_gid = 0, file_mode = 0;
snprintf(fn, PATH_MAX, "system/%s%s%s", subdir, sep, e->d_name);
fs_config(fn, 0, &file_uid, &file_gid, &file_mode);
// If this is the first file, its mode gets to become the default.
if (is_first && (
dir_mode != default_dir_mode ||
file_mode != default_file_mode ||
dir_uid != default_uid || file_uid != default_uid ||
dir_gid != default_gid || file_gid != default_gid)) {
default_uid = dir_uid;
default_gid = dir_gid;
default_dir_mode = dir_mode;
default_file_mode = file_mode;
printf("set_perm_recursive %d %d 0%o 0%o SYSTEM:%s\n",
default_uid, default_gid,
default_dir_mode, default_file_mode,
subdir);
}
is_first = 0;
// Otherwise, override this file if it doesn't match the defaults.
if (file_mode != default_file_mode ||
file_uid != default_uid || file_gid != default_gid) {
printf("set_perm %d %d 0%o SYSTEM:%s%s%s\n",
file_uid, file_gid, file_mode,
subdir, sep, e->d_name);
}
}
}
// Set the directory's permissions directly, if they never got set.
if (dir_mode != default_dir_mode ||
dir_uid != default_uid || dir_gid != default_gid) {
printf("set_perm %d %d 0%o SYSTEM:%s\n",
dir_uid, dir_gid, dir_mode, subdir);
}
closedir(dir);
}
/*
* Generate the update script (in "Amend", see commands/recovery/commands.c)
* for the complete-reinstall OTA update packages the build system makes.
*
* The generated script makes a variety of sanity checks about the device,
* erases and reinstalls system files, and sets file permissions appropriately.
*/
int main(int argc, char *argv[]) {
if (argc != 3) {
fprintf(stderr, "usage: %s systemdir android-info.txt >update-script\n",
argv[0]);
return 2;
}
// ensure basic recovery script language compatibility
printf("assert compatible_with(\"0.2\") == \"true\"\n");
// if known, make sure the device name is correct
const char *device = getenv("TARGET_DEVICE");
if (device != NULL) {
printf("assert getprop(\"ro.product.device\") == \"%s\" || "
"getprop(\"ro.build.product\") == \"%s\"\n", device, device);
}
// scan android-info.txt to enforce compatibility with the target system
FILE *fp = fopen(argv[2], "r");
if (fp == NULL) {
perror(argv[2]);
return 1;
}
// The lines we're looking for look like:
// version-bootloader=x.yy.zzzz
// or:
// require version-bootloader=x.yy.zzzz
char line[256];
while (fgets(line, sizeof(line), fp)) {
const char *name = strtok(line, "="), *value = strtok(NULL, "\n");
if (value != NULL &&
(!strcmp(name, "version-bootloader") ||
!strcmp(name, "require version-bootloader"))) {
printf("assert getprop(\"ro.bootloader\") == \"%s\"\n", value);
}
// We also used to check version-baseband, but we update radio.img
// ourselves, so there's no need.
}
// erase the boot sector first, so if the update gets interrupted,
// the system will reboot into the recovery partition and start over.
printf("format BOOT:\n");
// write the radio image (actually just loads it into RAM for now)
printf("show_progress 0.1 0\n");
printf("write_radio_image PACKAGE:radio.img\n");
// erase and reinstall the system image
printf("show_progress 0.5 0\n");
printf("format SYSTEM:\n");
printf("copy_dir PACKAGE:system SYSTEM:\n");
// walk the files in the system image, set their permissions, etc.
// use -1 for default values to force permissions to be set explicitly.
walk_files(argv[1], "", -1, -1, -1, -1);
// as the last step, write the boot sector.
printf("show_progress 0.2 0\n");
printf("write_raw_image PACKAGE:boot.img BOOT:\n");
// after the end of the script, the radio will be written to cache
// leave some space in the progress bar for this operation
printf("show_progress 0.2 10\n");
return 0;
}
