82 lines
1.5 KiB
C
82 lines
1.5 KiB
C
/*
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* linux/zBoot/xtract.c
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*
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* Copyright (C) 1993 Hannu Savolainen
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*
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* Extracts the system image and writes it to the stdout.
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* based on tools/build.c by Linus Torvalds
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*/
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#include <stdio.h> /* fprintf */
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#include <string.h>
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#include <stdlib.h> /* contains exit */
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#include <sys/types.h> /* unistd.h needs this */
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#include <sys/stat.h>
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#include <sys/sysmacros.h>
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#include <unistd.h> /* contains read/write */
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#include <fcntl.h>
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#include <a.out.h>
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#include <linux/config.h>
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#define GCC_HEADER 1024
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#define STRINGIFY(x) #x
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void die(char * str)
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{
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fprintf(stderr,"%s\n",str);
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exit(1);
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}
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void usage(void)
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{
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die("Usage: xtract system [ | gzip | piggyback > piggy.s]");
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}
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int main(int argc, char ** argv)
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{
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int i,c,id, sz;
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char buf[1024];
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char major_root, minor_root;
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struct stat sb;
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struct exec *ex = (struct exec *)buf;
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if (argc != 2)
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usage();
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if ((id=open(argv[1],O_RDONLY,0))<0)
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die("Unable to open 'system'");
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if (read(id,buf,GCC_HEADER) != GCC_HEADER)
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die("Unable to read header of 'system'");
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if (N_MAGIC(*ex) != ZMAGIC)
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die("Non-GCC header of 'system'");
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sz = N_SYMOFF(*ex) - GCC_HEADER + 4; /* +4 to get the same result than tools/build */
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fprintf(stderr, "System size is %d\n", sz);
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while (sz)
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{
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int l, n;
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l = sz;
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if (l > sizeof(buf)) l = sizeof(buf);
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if ((n=read(id, buf, l)) !=l)
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{
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if (n == -1)
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perror(argv[1]);
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else
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fprintf(stderr, "Unexpected EOF\n");
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die("Can't read system");
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}
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write(1, buf, l);
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sz -= l;
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}
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close(id);
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return(0);
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}
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