Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1
2#include <linux/kernel.h>
3#include <linux/dirent.h>
4#include <linux/string.h>
5
6#include "do_mounts.h"
7
8void __init mount_devfs(void)
9{
10 sys_mount("devfs", "/dev", "devfs", 0, NULL);
11}
12
13void __init umount_devfs(char *path)
14{
15 sys_umount(path, 0);
16}
17
18/*
19 * If the dir will fit in *buf, return its length. If it won't fit, return
20 * zero. Return -ve on error.
21 */
22static int __init do_read_dir(int fd, void *buf, int len)
23{
24 long bytes, n;
25 char *p = buf;
26 sys_lseek(fd, 0, 0);
27
28 for (bytes = 0; bytes < len; bytes += n) {
29 n = sys_getdents64(fd, (struct linux_dirent64 *)(p + bytes),
30 len - bytes);
31 if (n < 0)
32 return n;
33 if (n == 0)
34 return bytes;
35 }
36 return 0;
37}
38
39/*
40 * Try to read all of a directory. Returns the contents at *p, which
41 * is kmalloced memory. Returns the number of bytes read at *len. Returns
42 * NULL on error.
43 */
44static void * __init read_dir(char *path, int *len)
45{
46 int size;
47 int fd = sys_open(path, 0, 0);
48
49 *len = 0;
50 if (fd < 0)
51 return NULL;
52
53 for (size = 1 << 9; size <= (PAGE_SIZE << MAX_ORDER); size <<= 1) {
54 void *p = kmalloc(size, GFP_KERNEL);
55 int n;
56 if (!p)
57 break;
58 n = do_read_dir(fd, p, size);
59 if (n > 0) {
60 sys_close(fd);
61 *len = n;
62 return p;
63 }
64 kfree(p);
65 if (n == -EINVAL)
66 continue; /* Try a larger buffer */
67 if (n < 0)
68 break;
69 }
70 sys_close(fd);
71 return NULL;
72}
73
74/*
75 * recursively scan <path>, looking for a device node of type <dev>
76 */
77static int __init find_in_devfs(char *path, unsigned dev)
78{
79 char *end = path + strlen(path);
80 int rest = path + 64 - end;
81 int size;
82 char *p = read_dir(path, &size);
83 char *s;
84
85 if (!p)
86 return -1;
87 for (s = p; s < p + size; s += ((struct linux_dirent64 *)s)->d_reclen) {
88 struct linux_dirent64 *d = (struct linux_dirent64 *)s;
89 if (strlen(d->d_name) + 2 > rest)
90 continue;
91 switch (d->d_type) {
92 case DT_BLK:
93 sprintf(end, "/%s", d->d_name);
94 if (bstat(path) != dev)
95 break;
96 kfree(p);
97 return 0;
98 case DT_DIR:
99 if (strcmp(d->d_name, ".") == 0)
100 break;
101 if (strcmp(d->d_name, "..") == 0)
102 break;
103 sprintf(end, "/%s", d->d_name);
104 if (find_in_devfs(path, dev) < 0)
105 break;
106 kfree(p);
107 return 0;
108 }
109 }
110 kfree(p);
111 return -1;
112}
113
114/*
115 * create a device node called <name> which points to
116 * <devfs_name> if possible, otherwise find a device node
117 * which matches <dev> and make <name> a symlink pointing to it.
118 */
119int __init create_dev(char *name, dev_t dev, char *devfs_name)
120{
121 char path[64];
122
123 sys_unlink(name);
124 if (devfs_name && devfs_name[0]) {
125 if (strncmp(devfs_name, "/dev/", 5) == 0)
126 devfs_name += 5;
127 sprintf(path, "/dev/%s", devfs_name);
128 if (sys_access(path, 0) == 0)
129 return sys_symlink(devfs_name, name);
130 }
131 if (!dev)
132 return -1;
133 strcpy(path, "/dev");
134 if (find_in_devfs(path, new_encode_dev(dev)) < 0)
135 return -1;
136 return sys_symlink(path + 5, name);
137}