Merge "Add utility to prepare files in a similar way to directories" into nyc-dev (6a29fe93) · Commits · e / os / android_system_core

include/cutils/fs.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -51,6 +51,13 @@ extern int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid);
		*/
		extern int fs_prepare_dir_strict(const char* path, mode_t mode, uid_t uid, gid_t gid);

		/*
		* Ensure that file exists with given mode and owners. If it exists
		* with different owners, they are not fixed and -1 is returned.
		*/
		extern int fs_prepare_file_strict(const char* path, mode_t mode, uid_t uid, gid_t gid);


		/*
		* Read single plaintext integer from given file, correctly handling files
		* partially written with fs_write_atomic_int().

libcutils/fs.c

+24 −9

Original line number	Diff line number	Diff line
		@@ -37,10 +37,11 @@
		#define ALL_PERMS (S_ISUID \| S_ISGID \| S_ISVTX \| S_IRWXU \| S_IRWXG \| S_IRWXO)
		#define BUF_SIZE 64

		static int fs_prepare_dir_impl(const char* path, mode_t mode, uid_t uid, gid_t gid,
		int allow_fixup) {
		static int fs_prepare_path_impl(const char* path, mode_t mode, uid_t uid, gid_t gid,
		int allow_fixup, int prepare_as_dir) {
		// Check if path needs to be created
		struct stat sb;
		int create_result = -1;
		if (TEMP_FAILURE_RETRY(lstat(path, &sb)) == -1) {
		if (errno == ENOENT) {
		goto create;
		@@ -51,10 +52,12 @@ static int fs_prepare_dir_impl(const char* path, mode_t mode, uid_t uid, gid_t g
		}

		// Exists, verify status
		if (!S_ISDIR(sb.st_mode)) {
		ALOGE("Not a directory: %s", path);
		int type_ok = prepare_as_dir ? S_ISDIR(sb.st_mode) : S_ISREG(sb.st_mode);
		if (!type_ok) {
		ALOGE("Not a %s: %s", (prepare_as_dir ? "directory" : "regular file"), path);
		return -1;
		}

		int owner_match = ((sb.st_uid == uid) && (sb.st_gid == gid));
		int mode_match = ((sb.st_mode & ALL_PERMS) == mode);
		if (owner_match && mode_match) {
		@@ -74,13 +77,21 @@ static int fs_prepare_dir_impl(const char* path, mode_t mode, uid_t uid, gid_t g
		}

		create:
		if (TEMP_FAILURE_RETRY(mkdir(path, mode)) == -1) {
		create_result = prepare_as_dir
		? TEMP_FAILURE_RETRY(mkdir(path, mode))
		: TEMP_FAILURE_RETRY(open(path, O_CREAT \| O_CLOEXEC \| O_NOFOLLOW \| O_RDONLY));
		if (create_result == -1) {
		if (errno != EEXIST) {
		ALOGE("Failed to mkdir(%s): %s", path, strerror(errno));
		ALOGE("Failed to %s(%s): %s",
		(prepare_as_dir ? "mkdir" : "open"), path, strerror(errno));
		return -1;
		}
		} else if (!prepare_as_dir) {
		// For regular files we need to make sure we close the descriptor
		if (close(create_result) == -1) {
		ALOGW("Failed to close file after create %s: %s", path, strerror(errno));
		}
		}

		fixup:
		if (TEMP_FAILURE_RETRY(chmod(path, mode)) == -1) {
		ALOGE("Failed to chmod(%s, %d): %s", path, mode, strerror(errno));
		@@ -95,11 +106,15 @@ fixup:
		}

		int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) {
		return fs_prepare_dir_impl(path, mode, uid, gid, 1);
		return fs_prepare_path_impl(path, mode, uid, gid, /allow_fixup/ 1, /prepare_as_dir/ 1);
		}

		int fs_prepare_dir_strict(const char* path, mode_t mode, uid_t uid, gid_t gid) {
		return fs_prepare_dir_impl(path, mode, uid, gid, 0);
		return fs_prepare_path_impl(path, mode, uid, gid, /allow_fixup/ 0, /prepare_as_dir/ 1);
		}

		int fs_prepare_file_strict(const char* path, mode_t mode, uid_t uid, gid_t gid) {
		return fs_prepare_path_impl(path, mode, uid, gid, /allow_fixup/ 0, /prepare_as_dir/ 0);
		}

		int fs_read_atomic_int(const char* path, int* out_value) {