usr/kinit/name_to_dev.c

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <alloca.h>
#include <inttypes.h>

#include "do_mounts.h"
#include "kinit.h"

#define BUF_SZ		65536

/* Find dev_t for e.g. "hda,NULL" or "hdb,2" */
static dev_t try_name(char *name, int part)
{
	char path[BUF_SZ];
	char buf[BUF_SZ];
	int range;
	unsigned int major_num, minor_num;
	dev_t res;
	char *s;
	int len;
	int fd;

	/* read device number from /sys/block/.../dev */
	snprintf(path, sizeof(path), "/sys/block/%s/dev", name);
	fd = open(path, 0, 0);
	if (fd < 0)
		goto fail;
	len = read(fd, buf, BUF_SZ);
	close(fd);

	if (len <= 0 || len == BUF_SZ || buf[len - 1] != '\n')
		goto fail;
	buf[len - 1] = '\0';
	major_num = strtoul(buf, &s, 10);
	if (*s != ':')
		goto fail;
	minor_num = strtoul(s + 1, &s, 10);
	if (*s)
		goto fail;
	res = makedev(major_num, minor_num);

	/* if it's there and we are not looking for a partition - that's it */
	if (!part)
		return res;

	/* otherwise read range from .../range */
	snprintf(path, sizeof(path), "/sys/block/%s/range", name);
	fd = open(path, 0, 0);
	if (fd < 0)
		goto fail;
	len = read(fd, buf, 32);
	close(fd);
	if (len <= 0 || len == 32 || buf[len - 1] != '\n')
		goto fail;
	buf[len - 1] = '\0';
	range = strtoul(buf, &s, 10);
	if (*s)
		goto fail;

	/* if partition is within range - we got it */
	if (part < range) {
		dprintf("kinit: try_name %s,%d = %s\n", name, part,
			bdevname(res + part));
		return res + part;
	}

      fail:
	return (dev_t) 0;
}

/*
 *	Convert a name into device number.  We accept the following variants:
 *
 *	1) device number in hexadecimal	represents itself
 *	2) device number in major:minor decimal represents itself
 *	3) /dev/nfs represents Root_NFS
 *	4) /dev/<disk_name> represents the device number of disk
 *	5) /dev/<disk_name><decimal> represents the device number
 *         of partition - device number of disk plus the partition number
 *	6) /dev/<disk_name>p<decimal> - same as the above, that form is
 *	   used when disk name of partitioned disk ends on a digit.
 *	7) an actual block device node in the initramfs filesystem
 *
 *	If name doesn't have fall into the categories above, we return 0.
 *	Driverfs is used to check if something is a disk name - it has
 *	all known disks under bus/block/devices.  If the disk name
 *	contains slashes, name of driverfs node has them replaced with
 *	dots.  try_name() does the actual checks, assuming that driverfs
 *	is mounted on rootfs /sys.
 */

static inline dev_t name_to_dev_t_real(const char *name)
{
	char *p;
	dev_t res = 0;
	char *s;
	int part;
	struct stat st;
	int len;
	const char *devname;
	char *cptr, *e1, *e2;
	int major_num, minor_num;

	/* Are we a multi root line? */
	if (strchr(name, ','))
		return Root_MULTI;

	if (name[0] == '/') {
		devname = name;
	} else {
		char *dname = alloca(strlen(name) + 6);
		sprintf(dname, "/dev/%s", name);
		devname = dname;
	}

	if (!stat(devname, &st) && S_ISBLK(st.st_mode))
		return st.st_rdev;

	if (strncmp(name, "/dev/", 5)) {
		if ((cptr = strchr(devname+5, ':')) &&
		    cptr[1] != '\0') {
			/* Colon-separated decimal device number */
			*cptr = '\0';
			major_num = strtoul(devname+5, &e1, 10);
			minor_num = strtoul(cptr+1, &e2, 10);
			if (!*e1 && !*e2)
				return makedev(major_num, minor_num);
			*cptr = ':';
		} else {
			/* Hexadecimal device number */
			res = (dev_t) strtoul(name, &p, 16);
			if (!*p)
				return res;
		}
	} else {
		name += 5;
	}

	if (!strcmp(name, "nfs"))
		return Root_NFS;

	if (!strcmp(name, "ram")) /* /dev/ram - historic alias for /dev/ram0 */
		return Root_RAM0;

	if (!strncmp(name, "mtd", 3))
		return Root_MTD;

	len = strlen(name);
	s = alloca(len + 1);
	memcpy(s, name, len + 1);

	for (p = s; *p; p++)
		if (*p == '/')
			*p = '!';
	res = try_name(s, 0);
	if (res)
		return res;

	while (p > s && isdigit(p[-1]))
		p--;
	if (p == s || !*p || *p == '0')
		goto fail;
	part = strtoul(p, NULL, 10);
	*p = '\0';
	res = try_name(s, part);
	if (res)
		return res;

	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
		goto fail;
	p[-1] = '\0';
	res = try_name(s, part);
	return res;

fail:
	return (dev_t) 0;
}

dev_t name_to_dev_t(const char *name)
{
	dev_t dev = name_to_dev_t_real(name);

	dprintf("kinit: name_to_dev_t(%s) = %s\n", name, bdevname(dev));
	return dev;
}

#ifdef TEST_NAMETODEV		/* Standalone test */

int main(int argc, char *argv[])
{
	int i;

	for (i = 1; i < argc; i++)
		name_to_dev_t(argv[i]);

	return 0;
}

#endif
1	#include <ctype.h>
2	#include <errno.h>
3	#include <fcntl.h>
4	#include <sys/stat.h>
5	#include <stdio.h>
6	#include <stdlib.h>
7	#include <string.h>
8	#include <unistd.h>
9	#include <alloca.h>
10	#include <inttypes.h>
11
12	#include "do_mounts.h"
13	#include "kinit.h"
14
15	#define BUF_SZ 65536
16
17	/* Find dev_t for e.g. "hda,NULL" or "hdb,2" */
18	static dev_t try_name(char *name, int part)
19	{
20	char path[BUF_SZ];
21	char buf[BUF_SZ];
22	int range;
23	unsigned int major_num, minor_num;
24	dev_t res;
25	char *s;
26	int len;
27	int fd;
28
29	/* read device number from /sys/block/.../dev */
30	snprintf(path, sizeof(path), "/sys/block/%s/dev", name);
31	fd = open(path, 0, 0);
32	if (fd < 0)
33	goto fail;
34	len = read(fd, buf, BUF_SZ);
35	close(fd);
36
37	if (len <= 0 \|\| len == BUF_SZ \|\| buf[len - 1] != '\n')
38	goto fail;
39	buf[len - 1] = '\0';
40	major_num = strtoul(buf, &s, 10);
41	if (*s != ':')
42	goto fail;
43	minor_num = strtoul(s + 1, &s, 10);
44	if (*s)
45	goto fail;
46	res = makedev(major_num, minor_num);
47
48	/* if it's there and we are not looking for a partition - that's it */
49	if (!part)
50	return res;
51
52	/* otherwise read range from .../range */
53	snprintf(path, sizeof(path), "/sys/block/%s/range", name);
54	fd = open(path, 0, 0);
55	if (fd < 0)
56	goto fail;
57	len = read(fd, buf, 32);
58	close(fd);
59	if (len <= 0 \|\| len == 32 \|\| buf[len - 1] != '\n')
60	goto fail;
61	buf[len - 1] = '\0';
62	range = strtoul(buf, &s, 10);
63	if (*s)
64	goto fail;
65
66	/* if partition is within range - we got it */
67	if (part < range) {
68	dprintf("kinit: try_name %s,%d = %s\n", name, part,
69	bdevname(res + part));
70	return res + part;
71	}
72
73	fail:
74	return (dev_t) 0;
75	}
76
77	/*
78	* Convert a name into device number. We accept the following variants:
79	*
80	* 1) device number in hexadecimal represents itself
81	* 2) device number in major:minor decimal represents itself
82	* 3) /dev/nfs represents Root_NFS
83	* 4) /dev/<disk_name> represents the device number of disk
84	* 5) /dev/<disk_name><decimal> represents the device number
85	* of partition - device number of disk plus the partition number
86	* 6) /dev/<disk_name>p<decimal> - same as the above, that form is
87	* used when disk name of partitioned disk ends on a digit.
88	* 7) an actual block device node in the initramfs filesystem
89	*
90	* If name doesn't have fall into the categories above, we return 0.
91	* Driverfs is used to check if something is a disk name - it has
92	* all known disks under bus/block/devices. If the disk name
93	* contains slashes, name of driverfs node has them replaced with
94	* dots. try_name() does the actual checks, assuming that driverfs
95	* is mounted on rootfs /sys.
96	*/
97
98	static inline dev_t name_to_dev_t_real(const char *name)
99	{
100	char *p;
101	dev_t res = 0;
102	char *s;
103	int part;
104	struct stat st;
105	int len;
106	const char *devname;
107	char cptr, e1, *e2;
108	int major_num, minor_num;
109
110	/* Are we a multi root line? */
111	if (strchr(name, ','))
112	return Root_MULTI;
113
114	if (name[0] == '/') {
115	devname = name;
116	} else {
117	char *dname = alloca(strlen(name) + 6);
118	sprintf(dname, "/dev/%s", name);
119	devname = dname;
120	}
121
122	if (!stat(devname, &st) && S_ISBLK(st.st_mode))
123	return st.st_rdev;
124
125	if (strncmp(name, "/dev/", 5)) {
126	if ((cptr = strchr(devname+5, ':')) &&
127	cptr[1] != '\0') {
128	/* Colon-separated decimal device number */
129	*cptr = '\0';
130	major_num = strtoul(devname+5, &e1, 10);
131	minor_num = strtoul(cptr+1, &e2, 10);
132	if (!e1 && !e2)
133	return makedev(major_num, minor_num);
134	*cptr = ':';
135	} else {
136	/* Hexadecimal device number */
137	res = (dev_t) strtoul(name, &p, 16);
138	if (!*p)
139	return res;
140	}
141	} else {
142	name += 5;
143	}
144
145	if (!strcmp(name, "nfs"))
146	return Root_NFS;
147
148	if (!strcmp(name, "ram")) /* /dev/ram - historic alias for /dev/ram0 */
149	return Root_RAM0;
150
151	if (!strncmp(name, "mtd", 3))
152	return Root_MTD;
153
154	len = strlen(name);
155	s = alloca(len + 1);
156	memcpy(s, name, len + 1);
157
158	for (p = s; *p; p++)
159	if (*p == '/')
160	*p = '!';
161	res = try_name(s, 0);
162	if (res)
163	return res;
164
165	while (p > s && isdigit(p[-1]))
166	p--;
167	if (p == s \|\| !p \|\| p == '0')
168	goto fail;
169	part = strtoul(p, NULL, 10);
170	*p = '\0';
171	res = try_name(s, part);
172	if (res)
173	return res;
174
175	if (p < s + 2 \|\| !isdigit(p[-2]) \|\| p[-1] != 'p')
176	goto fail;
177	p[-1] = '\0';
178	res = try_name(s, part);
179	return res;
180
181	fail:
182	return (dev_t) 0;
183	}
184
185	dev_t name_to_dev_t(const char *name)
186	{
187	dev_t dev = name_to_dev_t_real(name);
188
189	dprintf("kinit: name_to_dev_t(%s) = %s\n", name, bdevname(dev));
190	return dev;
191	}
192
193	#ifdef TEST_NAMETODEV /* Standalone test */
194
195	int main(int argc, char *argv[])
196	{
197	int i;
198
199	for (i = 1; i < argc; i++)
200	name_to_dev_t(argv[i]);
201
202	return 0;
203	}
204
205	#endif