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  1. /*
  2.  * Name:         mycat
  3.  * Author:       Manuel Mausz, 0728348
  4.  * Description:  A simplified version of cat
  5.  * Created:      11.03.2009
  6.  * Exercise:     1h A
  7.  */
  8.  
  9. #include <unistd.h>
  10. #include <stdlib.h>
  11. #include <stdio.h>
  12. #include <errno.h>
  13. #include <string.h>
  14.  
  15. /* global variables */
  16. char *me;      /* name of myself (argv[0]) */
  17. int vflag = 0; /* cmdline option: -v set */
  18. int eflag = 0; /* cmdline option: -e set */
  19. int tflag = 0; /* cmdline option: -t set */
  20.  
  21. /*
  22.  * NAME: scan
  23.  * PURPOSE:
  24.  * reads characters from stream, converts them according the
  25.  * commandline options and print the converted characters on stdout
  26.  *
  27.  * PARAMETERS:
  28.  * FILE *fp ... pointer to a stream to read from
  29.  *
  30.  * RETURN VALUE:
  31.  * void
  32.  *
  33.  * GLOBAL VARS:
  34.  * vflag, eflag, tflag
  35.  */
  36. void scan(FILE *fp)
  37. {
  38.   int ch;
  39.  
  40.   while((ch = getc(fp)) != EOF)
  41.   {
  42.     /* eflag: print '$' before '\n' */
  43.     if (ch == '\n')
  44.     {
  45.       if (eflag && putchar('$') == EOF)
  46.         break;
  47.     }
  48.     /* tflag: print '^I' instead of '\t' */
  49.     else if (ch == '\t')
  50.     {
  51.       if (tflag)
  52.       {
  53.         if (putchar('^') == EOF || putchar('I') == EOF)
  54.           break;
  55.         continue;
  56.       }
  57.     }
  58.     /* vflag */
  59.     else if (vflag)
  60.     {
  61.       /* 128 <= ch <= 255: print 'M-'.(ch-128) */
  62.       if (128 <= ch && ch <= 255)
  63.       {
  64.         if (putchar('M') == EOF || putchar('-') == EOF)
  65.           break;
  66.         ch = ch - 128;
  67.       }
  68.  
  69.       /* 0 <= ch <= 31: print '^'.(ch+'@') */
  70.       if (0 <= ch && ch <= 31)
  71.       {
  72.         if (putchar('^') == EOF || putchar(ch + '@') == EOF)
  73.           break;
  74.         continue;
  75.       }
  76.       /* ch == 27: print '^?' */
  77.       else if (ch == 127)
  78.       {
  79.         if (putchar('^') == EOF || putchar('?') == EOF)
  80.           break;
  81.         continue;
  82.       }
  83.     }
  84.  
  85.     /* print character to stdout */
  86.     if (putchar(ch) == EOF)
  87.       break;
  88.   }
  89. }
  90.  
  91. /*
  92.  * NAME: usage
  93.  * PURPOSE:
  94.  * prints program usage to stderr and terminates with EXIT_FAILURE
  95.  *
  96.  * PARAMETERS:
  97.  * void
  98.  *
  99.  * RETURN VALUE:
  100.  * void
  101.  *
  102.  * GLOBAL VARS:
  103.  * me
  104.  */
  105. static void usage(void)
  106. {
  107.   (void) fprintf(stderr, "Usage: %s [-vET]\n", me);
  108.   (void) exit(EXIT_FAILURE);
  109. }
  110.  
  111. /*
  112.  * NAME: main
  113.  * PURPOSE:
  114.  * parses commandline options and calls scan()
  115.  *
  116.  * PARAMETERS:
  117.  * standard parameters of main(...)
  118.  *
  119.  * RETURN VALUE:
  120.  * int ... always 0
  121.  *
  122.  * GLOBAL VARS:
  123.  * me, vflag, eflag, tflag
  124.  */
  125. int main(int argc, char *argv[])
  126. {
  127.   int opt;
  128.  
  129.   me = argv[0];
  130.   while ((opt = getopt(argc, argv, "vET")) != -1)
  131.   {
  132.     switch(opt)
  133.     {
  134.       case 'v':
  135.         vflag = 1;
  136.         break;
  137.       case 'E':
  138.         eflag = 1;
  139.         break;
  140.       case 'T':
  141.         tflag = 1;
  142.         break;
  143.       default:
  144.         (void) usage();
  145.         break;
  146.     }
  147.   }
  148.  
  149.   (void) scan(stdin);
  150.   return 0;
  151. }
  152.  
  153. /* vim: set et sw=2 ts=2: */
  154.