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/* makehole.c - original by HJ Lu */
/* Patched by faith@cs.unc.edu, Wed Oct 6 18:01:39 1993 based on
information from Michael Bischoff <mbi@mo.math.nat.tu-bs.de> (Fri, 18
Jun 93 10:10:19 +0200). */
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <a.out.h>
#define BUFSIZE 1024
#undef DEBUG
void usage(char *name, char *message)
{
if (message)
fprintf(stderr, "%s: %s\n", name, message);
if (errno)
perror(name);
fprintf(stderr, "Usage:%s Imagefile\n", name);
exit(1);
}
int ishole(char *buf, int size)
{
int i;
for (i = 0; i < size; i++)
if (buf[i])
return 0;
return 1;
}
void main(int argc, char *argv[])
{
char buf[BUFSIZE];
char tmp_file[64];
int fdin, fdout;
int ret;
int abs_offset;
int hole;
struct exec *header = (struct exec *) buf;
#ifndef DEBUG
if (geteuid()) {
fprintf(stderr, "%s: must be root to run!\n", *argv);
exit(1);
}
#endif
switch (argc) {
case 2:
break;
default:
usage(*argv, NULL);
}
errno = 0;
sprintf( tmp_file, "hole%d", getpid() );
if (tmp_file == NULL) {
usage(*argv, "Unable to get a temporary image filename!");
}
#ifdef DEBUG
else {
fprintf(stderr, "Temparory image file: %s\n", tmp_file);
}
#endif
errno = 0;
fdin = open(argv[1], O_RDONLY);
if (fdin == -1) {
usage(*argv, "unable to open file.");
}
fprintf(stderr, "Making holes in %s...\n", argv[1]);
errno = 0;
if ((ret = read(fdin, header, BUFSIZE)) != BUFSIZE
|| N_MAGIC(*header) != ZMAGIC) {
usage(*argv, "file must be pure executable.");
}
fdout = creat(tmp_file, 0555);
if (fdout == -1) {
perror("Unable to create the temparory image file!");
exit(1);
}
if (write(fdout, header, ret) != ret) {
perror("Fail to write header to the temparory image file!");
unlink(tmp_file);
exit(1);
}
abs_offset = ret;
hole = 0;
while ((ret = read(fdin, buf, BUFSIZE)) > 0) {
abs_offset += ret;
if (ishole(buf, ret)) {
#ifdef DEBUG
fprintf(stderr, "There is a %d byte hole from 0x%x to 0x%x.\n", ret, abs_offset - ret, abs_offset);
#endif
hole += ret;
if (lseek(fdout, abs_offset, SEEK_SET) != abs_offset) {
perror("Fail to make a hole in the temparory image file!");
unlink(tmp_file);
exit(1);
}
} else {
#ifdef DEBUG
fprintf(stderr, "Writing %d bytes from 0x%x to 0x%x.\n", ret, abs_offset - ret, abs_offset);
#endif
if (write(fdout, buf, ret) != ret) {
perror("Fail to write the temparory image file!");
unlink(tmp_file);
exit(1);
}
}
}
if (ftruncate(fdout, abs_offset)) {
perror("Fail to truncate the temparory image file!");
unlink(tmp_file);
exit(1);
}
close(fdout);
close(fdin);
if (rename(tmp_file, argv[1])) {
perror("Fail to rename the temparory image file to the old image file!");
unlink(tmp_file);
exit(1);
}
fprintf(stderr, "There are %d byte holes out of %d bytes in `%s'.\n", hole, abs_offset, argv[1]);
}
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