1 /* $Id: piggyback.c,v 1.4 2000/12/05 00:48:57 anton Exp $
2 Simple utility to make a single-image install kernel with initial ramdisk
3 for Sparc tftpbooting without need to set up nfs.
4
5 Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
6 Pete Zaitcev <zaitcev@yahoo.com> endian fixes for cross-compiles, 2000.
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
21
22 #include <stdio.h>
23 #include <string.h>
24 #include <ctype.h>
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <dirent.h>
28 #include <unistd.h>
29 #include <stdlib.h>
30 #include <sys/types.h>
31 #include <sys/stat.h>
32
33 /*
34 * Note: run this on an a.out kernel (use elftoaout for it),
35 * as PROM looks for a.out image only.
36 */
37
38 unsigned short ld2(char *p)
39 {
40 return (p[0] << 8) | p[1];
41 }
42
43 unsigned int ld4(char *p)
44 {
45 return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
46 }
47
48 void st4(char *p, unsigned int x)
49 {
50 p[0] = x >> 24;
51 p[1] = x >> 16;
52 p[2] = x >> 8;
53 p[3] = x;
54 }
55
56 void usage(void)
57 {
58 /* fs_img.gz is an image of initial ramdisk. */
59 fprintf(stderr, "Usage: piggyback vmlinux.aout System.map fs_img.gz\n");
60 fprintf(stderr, "\tKernel image will be modified in place.\n");
61 exit(1);
62 }
63
64 void die(char *str)
65 {
66 perror (str);
67 exit(1);
68 }
69
70 int main(int argc,char **argv)
71 {
72 static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
73 unsigned char buffer[1024], *q, *r;
74 unsigned int i, j, k, start, end, offset;
75 FILE *map;
76 struct stat s;
77 int image, tail;
78
79 if (argc != 4) usage();
80 start = end = 0;
81 if (stat (argv[3], &s) < 0) die (argv[3]);
82 map = fopen (argv[2], "r");
83 if (!map) die(argv[2]);
84 while (fgets (buffer, 1024, map)) {
85 if (!strcmp (buffer + 8, " T start\n") || !strcmp (buffer + 16, " T start\n"))
86 start = strtoul (buffer, NULL, 16);
87 else if (!strcmp (buffer + 8, " A end\n") || !strcmp (buffer + 16, " A end\n"))
88 end = strtoul (buffer, NULL, 16);
89 }
90 fclose (map);
91 if (!start || !end) {
92 fprintf (stderr, "Could not determine start and end from System.map\n");
93 exit(1);
94 }
95 if ((image = open(argv[1],O_RDWR)) < 0) die(argv[1]);
96 if (read(image,buffer,512) != 512) die(argv[1]);
97 if (memcmp (buffer, "\177ELF", 4) == 0) {
98 q = buffer + ld4(buffer + 28);
99 i = ld4(q + 4) + ld4(buffer + 24) - ld4(q + 8);
100 if (lseek(image,i,0) < 0) die("lseek");
101 if (read(image,buffer,512) != 512) die(argv[1]);
102 j = 0;
103 } else if (memcmp(buffer, aout_magic, 4) == 0) {
104 i = j = 32;
105 } else {
106 fprintf (stderr, "Not ELF nor a.out. Don't blame me.\n");
107 exit(1);
108 }
109 k = i;
110 i += (ld2(buffer + j + 2)<<2) - 512;
111 if (lseek(image,i,0) < 0) die("lseek");
112 if (read(image,buffer,1024) != 1024) die(argv[1]);
113 for (q = buffer, r = q + 512; q < r; q += 4) {
114 if (*q == 'H' && q[1] == 'd' && q[2] == 'r' && q[3] == 'S')
115 break;
116 }
117 if (q == r) {
118 fprintf (stderr, "Couldn't find headers signature in the kernel.\n");
119 exit(1);
120 }
121 offset = i + (q - buffer) + 10;
122 if (lseek(image, offset, 0) < 0) die ("lseek");
123
124 st4(buffer, 0);
125 st4(buffer + 4, 0x01000000);
126 st4(buffer + 8, (end + 32 + 4095) & ~4095);
127 st4(buffer + 12, s.st_size);
128
129 if (write(image,buffer+2,14) != 14) die (argv[1]);
130 if (lseek(image, k - start + ((end + 32 + 4095) & ~4095), 0) < 0) die ("lseek");
131 if ((tail = open(argv[3],O_RDONLY)) < 0) die(argv[3]);
132 while ((i = read (tail,buffer,1024)) > 0)
133 if (write(image,buffer,i) != i) die (argv[1]);
134 if (close(image) < 0) die("close");
135 if (close(tail) < 0) die("close");
136 return 0;
137 }
138
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