historic/makehole.c

   1 /* makehole.c - original by HJ Lu */
   2
   3 /* Patched by faith@cs.unc.edu, Wed Oct 6 18:01:39 1993 based on
   4    information from Michael Bischoff <mbi@mo.math.nat.tu-bs.de> (Fri, 18
   5    Jun 93 10:10:19 +0200).  */
   6
   7 #include <unistd.h>
   8 #include <fcntl.h>
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #include <errno.h>
  12 #include <a.out.h>
  13
  14 #define BUFSIZE 1024
  15 #undef DEBUG
  16
  17 void usage(char *name, char *message)
  18 {
  19     if (message)
  20         fprintf(stderr, "%s: %s\n", name, message);
  21
  22     if (errno)
  23         perror(name);
  24
  25     fprintf(stderr, "Usage:%s Imagefile\n", name);
  26     exit(1);
  27 }
  28
  29 int ishole(char *buf, int size)
  30 {
  31     int i;
  32
  33     for (i = 0; i < size; i++)
  34         if (buf[i])
  35             return 0;
  36
  37     return 1;
  38 }
  39
  40 void main(int argc, char *argv[])
  41 {
  42     char buf[BUFSIZE];
  43     char tmp_file[64];
  44     int fdin, fdout;
  45     int ret;
  46     int abs_offset;
  47     int hole;
  48     struct exec *header = (struct exec *) buf;
  49
  50 #ifndef DEBUG
  51     if (geteuid()) {
  52         fprintf(stderr, "%s: must be root to run!\n", *argv);
  53         exit(1);
  54     }
  55 #endif
  56
  57     switch (argc) {
  58     case 2:
  59         break;
  60     default:
  61         usage(*argv, NULL);
  62     }
  63
  64     errno = 0;
  65
  66     sprintf( tmp_file, "hole%d", getpid() );
  67     if (tmp_file == NULL) {
  68         usage(*argv, "Unable to get a temporary image filename!");
  69     }
  70 #ifdef DEBUG
  71     else {
  72         fprintf(stderr, "Temparory image file: %s\n", tmp_file);
  73     }
  74 #endif
  75
  76     errno = 0;
  77     fdin = open(argv[1], O_RDONLY);
  78     if (fdin == -1) {
  79         usage(*argv, "unable to open file.");
  80     }
  81     fprintf(stderr, "Making holes in %s...\n", argv[1]);
  82
  83     errno = 0;
  84
  85     if ((ret = read(fdin, header, BUFSIZE)) != BUFSIZE
  86         || N_MAGIC(*header) != ZMAGIC) {
  87         usage(*argv, "file must be pure executable.");
  88     }
  89
  90     fdout = creat(tmp_file, 0555);
  91     if (fdout == -1) {
  92         perror("Unable to create the temparory image file!");
  93         exit(1);
  94     }
  95     if (write(fdout, header, ret) != ret) {
  96         perror("Fail to write header to the temparory image file!");
  97         unlink(tmp_file);
  98         exit(1);
  99     }
 100     abs_offset = ret;
 101     hole = 0;
 102     while ((ret = read(fdin, buf, BUFSIZE)) > 0) {
 103         abs_offset += ret;
 104         if (ishole(buf, ret)) {
 105 #ifdef DEBUG
 106             fprintf(stderr, "There is a %d byte hole from 0x%x to 0x%x.\n", ret, abs_offset - ret, abs_offset);
 107 #endif
 108             hole += ret;
 109             if (lseek(fdout, abs_offset, SEEK_SET) != abs_offset) {
 110                 perror("Fail to make a hole in the temparory image file!");
 111                 unlink(tmp_file);
 112                 exit(1);
 113             }
 114         } else {
 115 #ifdef DEBUG
 116             fprintf(stderr, "Writing %d bytes from 0x%x to 0x%x.\n", ret, abs_offset - ret, abs_offset);
 117 #endif
 118             if (write(fdout, buf, ret) != ret) {
 119                 perror("Fail to write the temparory image file!");
 120                 unlink(tmp_file);
 121                 exit(1);
 122             }
 123         }
 124     }
 125
 126     if (ftruncate(fdout, abs_offset)) {
 127         perror("Fail to truncate the temparory image file!");
 128         unlink(tmp_file);
 129         exit(1);
 130     }
 131     close(fdout);
 132     close(fdin);
 133
 134     if (rename(tmp_file, argv[1])) {
 135         perror("Fail to rename the temparory image file to the old image file!");
 136         unlink(tmp_file);
 137         exit(1);
 138     }
 139     fprintf(stderr, "There are %d byte holes out of %d bytes in `%s'.\n", hole, abs_offset, argv[1]);
 140 }