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] /boston/2012/01/17.1 | [2] http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html | [3] /boston/2012/01/18.1 | [4] /boston/2012/01/20.2

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