1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2 #pragma once
3
4 #include <inttypes.h>
5 #include <stdbool.h>
6 #include <sys/types.h>
7
8 #include "stdio-util.h"
9
10 int parse_devnum(const char *s, dev_t *ret);
11
12 /* glibc and the Linux kernel have different ideas about the major/minor size. These calls will check whether the
13 * specified major is valid by the Linux kernel's standards, not by glibc's. Linux has 20bits of minor, and 12 bits of
14 * major space. See MINORBITS in linux/kdev_t.h in the kernel sources. (If you wonder why we define _y here, instead of
15 * comparing directly >= 0: it's to trick out -Wtype-limits, which would otherwise complain if the type is unsigned, as
16 * such a test would be pointless in such a case.) */
17
18 #define DEVICE_MAJOR_VALID(x) \
19 ({ \
20 typeof(x) _x = (x), _y = 0; \
21 _x >= _y && _x < (UINT32_C(1) << 12); \
22 \
23 })
24
25 #define DEVICE_MINOR_VALID(x) \
26 ({ \
27 typeof(x) _x = (x), _y = 0; \
28 _x >= _y && _x < (UINT32_C(1) << 20); \
29 })
30
31 int device_path_make_major_minor(mode_t mode, dev_t devnum, char **ret);
32 int device_path_make_canonical(mode_t mode, dev_t devnum, char **ret);
33 int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devnum);
34
devnum_set_and_equal(dev_t a,dev_t b)35 static inline bool devnum_set_and_equal(dev_t a, dev_t b) {
36 /* Returns true if a and b definitely refer to the same device. If either is zero, this means "don't
37 * know" and we'll return false */
38 return a == b && a != 0;
39 }
40
41 /* Maximum string length for a major:minor string. (Note that DECIMAL_STR_MAX includes space for a trailing NUL) */
42 #define DEVNUM_STR_MAX (DECIMAL_STR_MAX(dev_t)-1+1+DECIMAL_STR_MAX(dev_t))
43
44 #define DEVNUM_FORMAT_STR "%u:%u"
45 #define DEVNUM_FORMAT_VAL(d) major(d), minor(d)
46
format_devnum(dev_t d,char buf[static DEVNUM_STR_MAX])47 static inline char *format_devnum(dev_t d, char buf[static DEVNUM_STR_MAX]) {
48 return ASSERT_PTR(snprintf_ok(buf, DEVNUM_STR_MAX, DEVNUM_FORMAT_STR, DEVNUM_FORMAT_VAL(d)));
49 }
50
51 #define FORMAT_DEVNUM(d) format_devnum((d), (char[DEVNUM_STR_MAX]) {})
52