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/* =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- */
/* Copyright (C) 2002,2005 by Duane H. Hesser. All rights reserved. */
/* */
/* See the file LICENSE.EXIFPROBE for terms of use. */
/* =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- */
/* This program extracts an arbitrary section of a file from */
/* 'start_offset' to 'end_offset', writing it to a file named with */
/* the original filename suffixed by ".%d-%d" start,end. */
/* section to be extracted may be specified by a second argument */
/* "@start:length" or by second and third arguments "start end". */
/* This is intended to extract sections from image files, and is much */
/* faster than 'dd' for the purpose. */
#ifndef lint
static char *ModuleId = "@(#) $Id: extract_section.c,v 1.1 2005/06/30 17:50:27 alex Exp $";
#endif
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <values.h>
#define END_OF_FILE MAXINT
#define COPYBUFSIZE 16384
#define NAMELENGTH 1024
extern char *optarg;
char *Progname;
main(int argc,char **argv)
{
char copybuf[COPYBUFSIZE];
char outfilename[NAMELENGTH];
char *arg,*infilename,*colon;
unsigned long start_offset = 0UL;
unsigned long end_offset = END_OF_FILE;
int opt;
FILE *ifp,*ofp;
int readsize = 0;
int bytesread = 0;
int byteswritten = 0;
int bytescopied = 0;
int sizeleft = 0;
int onamelength = 0;
Progname = *argv;
if(argc >= 2)
{
infilename = *++argv;
arg = *++argv;
if(arg && (*arg == '@'))
{
start_offset = strtoul(++arg,(char **)0,0);
colon = strchr(arg,':');
if(colon)
end_offset = start_offset + strtoul(++colon,(char **)0,0) - 1;
}
else if(arg)
{
start_offset = strtoul(arg,(char **)0,0);
if(*++argv)
{
arg = *argv;
end_offset = strtoul(arg,(char **)0,0);
}
}
}
if(infilename)
{
if(end_offset == END_OF_FILE)
onamelength = snprintf(outfilename,NAMELENGTH,"%s.%d-eof",infilename,start_offset);
else
onamelength = snprintf(outfilename,NAMELENGTH,"%s.%d-%d",infilename,start_offset,end_offset);
if(onamelength < (strlen(infilename) + 2))
{
fprintf(stderr,"%s: can't make output name",Progname);
perror("\tbecause");
exit(2);
}
}
else
{
fprintf(stderr,"%s: no input file name\n",Progname);
exit(1);
}
printf("copy from %s to %s\n",infilename,outfilename);
printf("start_offset = %lu, ",start_offset);
sizeleft = end_offset - start_offset + 1;
if(end_offset == END_OF_FILE)
printf("end_offset = end of file\n");
else
printf("end_offset = %d, copy length = %d\n",end_offset,sizeleft);
if((ifp = fopen(infilename,"r")) != (FILE *)0)
{
if((ofp = fopen(outfilename,"w")) == (FILE *)0)
{
fprintf(stderr,"%s: could not open output file \"%s\"\n",Progname,outfilename);
perror("\tbecause");
exit(3);
}
fseek(ifp,start_offset,SEEK_SET);
if(sizeleft < COPYBUFSIZE)
readsize = sizeleft;
else
readsize = COPYBUFSIZE;
while(sizeleft && ((bytesread = fread(copybuf,1,readsize,ifp)) > 0))
{
byteswritten = fwrite(copybuf,1,bytesread,ofp);
sizeleft -= byteswritten;
bytescopied += byteswritten;
if(sizeleft < COPYBUFSIZE)
readsize = sizeleft;
}
clearerr(ifp);
printf("copied %d bytes from %d to %d\n",bytescopied,start_offset,ftell(ifp) - 1);
}
else
{
fprintf(stderr,"%s: could not open input file \"%s\"\n",Progname,infilename);
perror("\tbecause");
exit(3);
}
exit(0);
}
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