Thursday, January 19, 2012
99 ways to program a hex, Part 11: C89, const correctness, assertive, GCC extensions
Today's code is identical to part
9 save for one line—it uses a GCC
extention 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); } } } /***************************************************************/