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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <string.h>
#include <sys/stat.h>
#include "chase-symlinks.h"
#include "devnum-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "string-util.h"
int parse_devnum(const char *s, dev_t *ret) {
const char *major;
unsigned x, y;
size_t n;
int r;
n = strspn(s, DIGITS);
if (n == 0)
return -EINVAL;
if (n > DECIMAL_STR_MAX(dev_t))
return -EINVAL;
if (s[n] != ':')
return -EINVAL;
major = strndupa_safe(s, n);
r = safe_atou(major, &x);
if (r < 0)
return r;
r = safe_atou(s + n + 1, &y);
if (r < 0)
return r;
if (!DEVICE_MAJOR_VALID(x) || !DEVICE_MINOR_VALID(y))
return -ERANGE;
*ret = makedev(x, y);
return 0;
}
int device_path_make_major_minor(mode_t mode, dev_t devnum, char **ret) {
const char *t;
/* Generates the /dev/{char|block}/MAJOR:MINOR path for a dev_t */
if (S_ISCHR(mode))
t = "char";
else if (S_ISBLK(mode))
t = "block";
else
return -ENODEV;
if (asprintf(ret, "/dev/%s/" DEVNUM_FORMAT_STR, t, DEVNUM_FORMAT_VAL(devnum)) < 0)
return -ENOMEM;
return 0;
}
int device_path_make_inaccessible(mode_t mode, char **ret) {
char *s;
assert(ret);
if (S_ISCHR(mode))
s = strdup("/run/systemd/inaccessible/chr");
else if (S_ISBLK(mode))
s = strdup("/run/systemd/inaccessible/blk");
else
return -ENODEV;
if (!s)
return -ENOMEM;
*ret = s;
return 0;
}
int device_path_make_canonical(mode_t mode, dev_t devnum, char **ret) {
_cleanup_free_ char *p = NULL;
int r;
/* Finds the canonical path for a device, i.e. resolves the /dev/{char|block}/MAJOR:MINOR path to the end. */
assert(ret);
if (major(devnum) == 0 && minor(devnum) == 0)
/* A special hack to make sure our 'inaccessible' device nodes work. They won't have symlinks in
* /dev/block/ and /dev/char/, hence we handle them specially here. */
return device_path_make_inaccessible(mode, ret);
r = device_path_make_major_minor(mode, devnum, &p);
if (r < 0)
return r;
return chase_symlinks(p, NULL, 0, ret, NULL);
}
int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devnum) {
mode_t mode;
dev_t devnum;
int r;
/* Tries to extract the major/minor directly from the device path if we can. Handles /dev/block/ and /dev/char/
* paths, as well out synthetic inaccessible device nodes. Never goes to disk. Returns -ENODEV if the device
* path cannot be parsed like this. */
if (path_equal(path, "/run/systemd/inaccessible/chr")) {
mode = S_IFCHR;
devnum = makedev(0, 0);
} else if (path_equal(path, "/run/systemd/inaccessible/blk")) {
mode = S_IFBLK;
devnum = makedev(0, 0);
} else {
const char *w;
w = path_startswith(path, "/dev/block/");
if (w)
mode = S_IFBLK;
else {
w = path_startswith(path, "/dev/char/");
if (!w)
return -ENODEV;
mode = S_IFCHR;
}
r = parse_devnum(w, &devnum);
if (r < 0)
return r;
}
if (ret_mode)
*ret_mode = mode;
if (ret_devnum)
*ret_devnum = devnum;
return 0;
}
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