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Offer a stricter way to prepare directories.

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Some callers, such as installd, have stricter requirements around
directory preparation, where they want to assert ownership and mode
without quietly fixing the values.

Bug: 26466827
Change-Id: Id44db5f29a3326cfe178b443fb450ad2edeaefd8
This commit is contained in:
Jeff Sharkey 2016-01-12 12:42:32 -07:00
parent ba01a14659
commit cf94fe152e
2 changed files with 22 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
include/cutils/fs.h
View file

@ -40,10 +40,17 @@ extern "C" {
#endif
/*
* Ensure that directory exists with given mode and owners.
* Ensure that directory exists with given mode and owners. If it exists
* with a different mode or owners, they are fixed to match the given values.
*/
extern int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid);
/*
* Ensure that directory exists with given mode and owners. If it exists
* with a different mode or owners, they are not fixed and -1 is returned.
*/
extern int fs_prepare_dir_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().

16
libcutils/fs.c
View file

@ -37,7 +37,8 @@
#define ALL_PERMS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
#define BUF_SIZE 64
int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) {
static int fs_prepare_dir_impl(const char* path, mode_t mode, uid_t uid, gid_t gid,
int allow_fixup) {
// Check if path needs to be created
struct stat sb;
if (TEMP_FAILURE_RETRY(lstat(path, &sb)) == -1) {
@ -56,8 +57,11 @@ int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) {
}
if (((sb.st_mode & ALL_PERMS) == mode) && (sb.st_uid == uid) && (sb.st_gid == gid)) {
return 0;
} else {
} else if (allow_fixup) {
goto fixup;
} else {
ALOGE("Path %s exists with unexpected permissions", path);
return -1;
}
create:
@ -81,6 +85,14 @@ fixup:
return 0;
}
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);
}
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);
}
int fs_read_atomic_int(const char* path, int* out_value) {
int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY));
if (fd == -1) {