diff --git a/src/basic/stat-util.h b/src/basic/stat-util.h index 84400a6083..fe4a4bb717 100644 --- a/src/basic/stat-util.h +++ b/src/basic/stat-util.h @@ -62,3 +62,22 @@ int fd_verify_regular(int fd); int stat_verify_directory(const struct stat *st); int fd_verify_directory(int fd); + +/* glibc and the Linux kernel have different ideas about the major/minor size. These calls will check whether the + * specified major is valid by the Linux kernel's standards, not by glibc's. Linux has 20bits of minor, and 12 bits of + * major space. See MINORBITS in linux/kdev_t.h in the kernel sources. (If you wonder why we define _y here, instead of + * comparing directly >= 0: it's to trick out -Wtype-limits, which would otherwise complain if the type is unsigned, as + * such a test would be pointless in such a case.) */ + +#define DEVICE_MAJOR_VALID(x) \ + ({ \ + typeof(x) _x = (x), _y = 0; \ + _x >= _y && _x < (UINT32_C(1) << 12); \ + \ + }) + +#define DEVICE_MINOR_VALID(x) \ + ({ \ + typeof(x) _x = (x), _y = 0; \ + _x >= _y && _x < (UINT32_C(1) << 20); \ + }) diff --git a/src/test/test-stat-util.c b/src/test/test-stat-util.c index 2b0564d8a0..713fbc9a08 100644 --- a/src/test/test-stat-util.c +++ b/src/test/test-stat-util.c @@ -81,12 +81,48 @@ static void test_fd_is_network_ns(void) { assert_se(IN_SET(fd_is_network_ns(fd), 1, -EUCLEAN)); } +static void test_device_major_minor_valid(void) { + /* on glibc dev_t is 64bit, even though in the kernel it is only 32bit */ + assert_cc(sizeof(dev_t) == sizeof(uint64_t)); + + assert_se(DEVICE_MAJOR_VALID(0U)); + assert_se(DEVICE_MINOR_VALID(0U)); + + assert_se(DEVICE_MAJOR_VALID(1U)); + assert_se(DEVICE_MINOR_VALID(1U)); + + assert_se(!DEVICE_MAJOR_VALID(-1U)); + assert_se(!DEVICE_MINOR_VALID(-1U)); + + assert_se(DEVICE_MAJOR_VALID(1U << 10)); + assert_se(DEVICE_MINOR_VALID(1U << 10)); + + assert_se(DEVICE_MAJOR_VALID((1U << 12) - 1)); + assert_se(DEVICE_MINOR_VALID((1U << 20) - 1)); + + assert_se(!DEVICE_MAJOR_VALID((1U << 12))); + assert_se(!DEVICE_MINOR_VALID((1U << 20))); + + assert_se(!DEVICE_MAJOR_VALID(1U << 25)); + assert_se(!DEVICE_MINOR_VALID(1U << 25)); + + assert_se(!DEVICE_MAJOR_VALID(UINT32_MAX)); + assert_se(!DEVICE_MINOR_VALID(UINT32_MAX)); + + assert_se(!DEVICE_MAJOR_VALID(UINT64_MAX)); + assert_se(!DEVICE_MINOR_VALID(UINT64_MAX)); + + assert_se(DEVICE_MAJOR_VALID(major(0))); + assert_se(DEVICE_MINOR_VALID(minor(0))); +} + int main(int argc, char *argv[]) { test_files_same(); test_is_symlink(); test_path_is_fs_type(); test_path_is_temporary_fs(); test_fd_is_network_ns(); + test_device_major_minor_valid(); return 0; }