apps/utils/echo.c

   1 /*
   2     meinOS - A unix-like x86 microkernel operating system
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation, either version 3 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <stddef.h>
  24
  25 void usage(char *prog,int ret) {
  26   FILE *stream = stdout;//ret==0?stdout:stderr;
  27   fprintf(stream,"Usage: %s [OPTION]... [STRING]...\n");
  28   fprintf(stream,"Echo the STRING(s) to standard output\n");
  29   fprintf(stream,"\t-n\tdo not output the trailing newline\n");
  30   fprintf(stream,"\t-e\tenable interpretation of backslash escapes\n");
  31   fprintf(stream,"\t-E\tdisable interpretation of backslash escapes (default)\n");
  32   fprintf(stream,"\t-h\tdisplay this help and exit\n");
  33   fprintf(stream,"\t-v\toutput version information and exit\n");
  34 }
  35
  36 int octal2num(char *str) {
  37   char buf[4];
  38   memcpy(buf,str,3);
  39   buf[3] = 0;
  40   int num = strtoul(buf,NULL,8);
  41   return num;
  42 }
  43
  44 char *escape_string(char *str,int *newline) {
  45   char *new = malloc(strlen(str)+1);
  46   size_t i,j;
  47   for (i=0,j=0;str[i];i++,j++) {
  48     if (str[i]=='\\' && str[i+1]!=0) {     // escape code
  49       i++;
  50       if (str[i]=='\\') new[j] = '\\';     // backslash
  51       else if (str[i]=='a') new[j] = '\a'; // alert
  52       else if (str[i]=='b') new[j] = '\b'; // backspace
  53       else if (str[i]=='c') *newline = 0;  // supress trailing newline
  54       else if (str[i]=='f') new[j] = '\f'; // form feed
  55       else if (str[i]=='n') new[j] = '\n'; // new line
  56       else if (str[i]=='r') new[j] = '\r'; // carriage return
  57       else if (str[i]=='t') new[j] = '\t'; // horizontal tab
  58       else if (str[i]=='v') new[j] = '\v'; // vertical tab
  59       else if (str[i]=='0' && str[i+1]!=0 && str[i+2]!=0 && str[i+3]!=0) {
  60                                            // character in octal
  61         new[j] = octal2num(str+i+1);
  62       }
  63     }
  64     else new[j] = str[i];
  65   }
  66   return new;
  67 }
  68
  69 int main(int argc,char *argv[]) {
  70   int c;
  71   int newline = 1;
  72   int escape = 0;
  73
  74   while ((c = getopt(argc,argv,":neEhv"))!=-1) {
  75     switch(c) {
  76       case 'n':
  77         newline = 0;
  78         break;
  79       case 'e':
  80         escape = 1;
  81         break;
  82       case 'E':
  83         escape = 0;
  84         break;
  85       case 'h':
  86         usage(argv[0],0);
  87         break;
  88       case 'v':
  89         printf("echo v0.1\n(c) 2008 Janosch Graef\n");
  90         return 0;
  91         break;
  92       case '?':
  93         fprintf(stderr,"Unrecognized option: -%c\n", optopt);
  94         usage(argv[0],1);
  95         break;
  96     }
  97   }
  98
  99   for (c=optind;c<argc;c++) {
 100     char *string;
 101     if (escape) string = escape_string(argv[c],&newline);
 102     else string = argv[c];
 103
 104     printf("%s",string);
 105     if (c<argc-1) putchar(' ');
 106
 107     if (escape) free(string);
 108   }
 109
 110   if (newline) putchar('\n');
 111
 112   return 0;
 113 }