* * * * *
                                        
   99 ways to program a hex, Part 11: C89, const correctness, assertive, GCC
                                   extensions
                                        
Today's code is identical to part 9 [1] save for one line—it uses a GCC
extention [2] to notify the compiler that the do_dump() function accepts NULL
pointers, and that it won't throw any exceptions.

> /*************************************************************************
> *
> * Copyright 2012 by Sean Conner.  All Rights Reserved.
> *
> * This program is free software; you can redistribute it and/or
> * modify it under the terms of the GNU General Public License
> * as published by the Free Software Foundation; either version 2
> * of the License, or (at your option) any later version.
> *
> * This program is distributed in the hope that it will be useful,
> * but WITHOUT ANY WARRANTY; without even the implied warranty of
> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> * GNU General Public License for more details.
> *
> * You should have received a copy of the GNU General Public License
> * along with this program; if not, write to the Free Software
> * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
> *
> * Comments, questions and criticisms can be sent to: sean@conman.org
> *
> *************************************************************************/
> 
> /* Style: C89, const correctness, assertive, GCC extensions */
> 
> #include <stdio.h>
> #include <ctype.h>
> #include <string.h>
> #include <stdlib.h>
> #include <assert.h>
> 
> #define LINESIZE	  16
> 
> static void 	do_dump		(FILE *const,FILE *const) __attribute__((nonnull,nothrow));
> 
> /****************************************************************/
> 
> int main(const int argc,char *const argv[])
> {
>   assert(argc    >= 1);
>   assert(argv    != NULL);
>   assert(argv[0] != NULL);
>   
>   if (argc == 1)
>     do_dump(stdin,stdout);
>   else
>   {
>     int i;
>     
>     for (i = 1 ; i < argc ; i++)
>     {
>       FILE *fp;
>       
>       fp = fopen(argv[i],"rb");
>       if (fp == NULL)
>       {
>         perror(argv[i]);
>         continue;
>       }
> 
>       printf("-----%s-----\n",argv[i]);
>       do_dump(fp,stdout);
>       fclose(fp);
>     }
>   }
> 
>   return EXIT_SUCCESS;
> }
> 
> /******************************************************************/
> 
> static void do_dump(FILE *const fpin,FILE *const fpout)
> {
>   unsigned char  buffer[BUFSIZ];
>   unsigned char *pbyte;
>   size_t         offset;
>   size_t         bread;
>   size_t         j;
>   char           ascii[LINESIZE + 1];
>   
>   assert(fpin  != NULL);
>   assert(fpout != NULL);
>   
>   offset = 0;
> 
>   while((bread = fread(buffer,1,BUFSIZ,fpin)) > 0)
>   {
>     pbyte = buffer;
>     while (bread > 0)
>     {
>       fprintf(fpout,"%08lX: ",(unsigned long)offset);
>       j = 0;
>       do
>       {
>         fprintf(fpout,"%02X ",*pbyte);
>         if (isprint(*pbyte))
>           ascii [j] = *pbyte;
>         else
>           ascii [j] = '.';
>         pbyte  ++;
>         offset ++;
>         j      ++;
>         bread  --;
>       } while ((j < LINESIZE) && (bread > 0));
>       ascii [j] = '\0';
>       if (j < LINESIZE)
>       {
> 	size_t i;
> 
> 	for (i = j ; i < LINESIZE ; i++) fprintf(fpout,"   ");
>       }
>       fprintf(fpout,"%s\n",ascii);      
>     }
>     
>     if (fflush(fpout) == EOF)
>     {
>       perror("output");
>       exit(EXIT_FAILURE);
>     }
>   }
> }
> 
> /***************************************************************/
> 

* Part 10: C99, const and restrict correctness, assertive [3]
* Part 12: C99, const and restrict correctness, assertive, GCC extensions [4]

[1] gopher://gopher.conman.org/0Phlog:2012/01/17.1
[2] http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
[3] gopher://gopher.conman.org/0Phlog:2012/01/18.1
[4] gopher://gopher.conman.org/0Phlog:2012/01/20.2

Email Sean Conner at sean@conman.org

.