1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/* ----------------------------------------------------------------------- *
*
* Copyright 2012 Intel Corporation; author H. Peter Anvin
*
* This file is part of the Linux kernel, and is made available
* under the terms of the GNU General Public License version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* ----------------------------------------------------------------------- */
/*
* earlycpio.c
*
* Find a specific cpio member; must precede any compressed content.
* This is used to locate data items in the initramfs used by the
* kernel itself during early boot (before the main initramfs is
* decompressed.) It is the responsibility of the initramfs creator
* to ensure that these items are uncompressed at the head of the
* blob. Depending on the boot loader or package tool that may be a
* separate file or part of the same file.
*/
#include <linux/earlycpio.h>
#include <linux/kernel.h>
#include <linux/string.h>
enum cpio_fields {
C_MAGIC,
C_INO,
C_MODE,
C_UID,
C_GID,
C_NLINK,
C_MTIME,
C_FILESIZE,
C_MAJ,
C_MIN,
C_RMAJ,
C_RMIN,
C_NAMESIZE,
C_CHKSUM,
C_NFIELDS
};
/**
* cpio_data find_cpio_data - Search for files in an uncompressed cpio
* @path: The directory to search for, including a slash at the end
* @data: Pointer to the the cpio archive or a header inside
* @len: Remaining length of the cpio based on data pointer
* @offset: When a matching file is found, this is the offset to the
* beginning of the cpio. It can be used to iterate through
* the cpio to find all files inside of a directory path
*
* @return: struct cpio_data containing the address, length and
* filename (with the directory path cut off) of the found file.
* If you search for a filename and not for files in a directory,
* pass the absolute path of the filename in the cpio and make sure
* the match returned an empty filename string.
*/
struct cpio_data __cpuinit find_cpio_data(const char *path, void *data,
size_t len, long *offset)
{
const size_t cpio_header_len = 8*C_NFIELDS - 2;
struct cpio_data cd = { NULL, 0, "" };
const char *p, *dptr, *nptr;
unsigned int ch[C_NFIELDS], *chp, v;
unsigned char c, x;
size_t mypathsize = strlen(path);
int i, j;
p = data;
while (len > cpio_header_len) {
if (!*p) {
/* All cpio headers need to be 4-byte aligned */
p += 4;
len -= 4;
continue;
}
j = 6; /* The magic field is only 6 characters */
chp = ch;
for (i = C_NFIELDS; i; i--) {
v = 0;
while (j--) {
v <<= 4;
c = *p++;
x = c - '0';
if (x < 10) {
v += x;
continue;
}
x = (c | 0x20) - 'a';
if (x < 6) {
v += x + 10;
continue;
}
goto quit; /* Invalid hexadecimal */
}
*chp++ = v;
j = 8; /* All other fields are 8 characters */
}
if ((ch[C_MAGIC] - 0x070701) > 1)
goto quit; /* Invalid magic */
len -= cpio_header_len;
dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
if (nptr > p + len || dptr < p || nptr < dptr)
goto quit; /* Buffer overrun */
if ((ch[C_MODE] & 0170000) == 0100000 &&
ch[C_NAMESIZE] >= mypathsize &&
!memcmp(p, path, mypathsize)) {
*offset = (long)nptr - (long)data;
if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
pr_warn(
"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",
p, MAX_CPIO_FILE_NAME);
}
strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);
cd.data = (void *)dptr;
cd.size = ch[C_FILESIZE];
return cd; /* Found it! */
}
len -= (nptr - p);
p = nptr;
}
quit:
return cd;
}
|
