fileops/hexdump.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>    /* for memset() */
   4 #include <getopt.h>
   5
   6 /* Function prototypes */
   7 void diep(const char *s);
   8 void dieu(const char *pname);
   9
  10 #define BUFSIZE 20    /* Must be dividable by 2 */
  11
  12 int main(int argc, char *argv[])
  13 {
  14     unsigned char buf[BUFSIZE + 1];    /* +1 for the '\0' */
  15     FILE *fp;
  16     int cnt, i, j, len, skip;
  17     int caps, opt;
  18     int readbytes, totalbytes = 0;
  19     char *fpath;
  20
  21     /* Parse arguments */
  22     caps = 0;
  23     len = -1;
  24     skip = 0;
  25     fpath = NULL;
  26     while ((opt = getopt(argc, argv, "Cn:s:f:")) != -1) {
  27         switch (opt) {
  28         case 'C':
  29             caps = 1;
  30             break;
  31         case 'n':
  32             len = atoi(optarg);
  33             break;
  34         case 's':
  35             skip = atoi(optarg);
  36             break;
  37         case 'f':
  38             fpath = optarg;
  39             break;
  40         default:    /* '?' */
  41             dieu(argv[0]);
  42         }
  43     }
  44
  45     /* optind shows to the argv[] index of the first non-option element */
  46     if (optind < argc) {
  47         fprintf(stderr, "non-option argv[]-elements: ");
  48         while (optind < argc)
  49             fprintf(stderr, "%s ", argv[optind++]);
  50         fprintf(stderr, "\n");
  51         exit(EXIT_FAILURE);
  52     }
  53
  54     if (fpath == NULL)
  55         dieu(argv[0]);
  56
  57     /* Open file */
  58     if ((fp = fopen(fpath, "r")) == NULL)
  59         diep("open");
  60
  61     /* Skip ``skip'' bytes */
  62     fseek(fp, skip, SEEK_SET);
  63
  64     /* Loop */
  65     cnt = 0;
  66     while(!feof(fp) && (totalbytes < len || len == -1)) {
  67         /* Initialize buffer */
  68         memset(buf, 0, BUFSIZE);
  69
  70         /* Read ``BUFSIZE'' elements of 1 byte long from file */
  71         readbytes = fread(buf, 1, BUFSIZE, fp);
  72
  73         /* Print buffer */
  74         printf(caps == 1 ? "%08lX " : "%08lx ", (unsigned long)cnt * BUFSIZE + skip);
  75         for (i = 0; i < readbytes && (totalbytes < len || len == -1); i++, totalbytes++) {
  76             printf(caps == 1 ? "%02X " : "%02x ", buf[i]);
  77             if (i == (BUFSIZE / 2) - 1)
  78                 printf(" ");
  79         }
  80
  81         /* Fill in the blanks */
  82         for (j = 0; j < (BUFSIZE - i); j++) {
  83             printf("   ");
  84             if (j == (BUFSIZE/2) - 1)
  85                 printf(" ");
  86         }
  87
  88         /*
  89          * Print the output characters in the default character set.
  90          * Nonprinting characters are displayed as a single ``.''
  91          */
  92         printf(" |");
  93         for (j = 0; j < i; j++) {
  94             if (buf[j] >= 32 && buf[j] <= 127)
  95                 printf("%c", buf[j]);
  96             else
  97                 printf(".");
  98         }
  99         printf("|");
 100
 101         /* New line */
 102         printf("\n");
 103
 104         cnt++;
 105     }
 106
 107     /* Close device file */
 108     (void)fclose(fp);
 109
 110     return EXIT_SUCCESS;
 111 }
 112
 113 void diep(const char *s)
 114 {
 115     perror(s);
 116     exit(EXIT_FAILURE);
 117 }
 118
 119 void dieu(const char *pname)
 120 {
 121     fprintf(stderr, "Usage: %s [-C] [-n length] [-s skip] -f file\n", pname);
 122     exit(EXIT_FAILURE);
 123 }