Sandbox::https://github.com/CoderLawrence/sqlcipher/blob/Xcode5/tool/extract.c

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** Extract a range of bytes from a file.

** Usage:

** extract FILENAME OFFSET AMOUNT

** The bytes are written to standard output.

#include <stdio.h>

#include <stdlib.h>

int main(int argc, char **argv){

FILE *f;

char *zBuf;

int ofst;

int n;

size_t got;

if( argc!=4 ){

fprintf(stderr, "Usage: %s FILENAME OFFSET AMOUNT\n", *argv);

return 1;

}

f = fopen(argv[1], "rb");

if( f==0 ){

fprintf(stderr, "cannot open \"%s\"\n", argv[1]);

return 1;

}

ofst = atoi(argv[2]);

n = atoi(argv[3]);

zBuf = malloc( n );

if( zBuf==0 ){

fprintf(stderr, "out of memory\n");

return 1;

}

fseek(f, ofst, SEEK_SET);

got = fread(zBuf, 1, n, f);

fclose(f);

if( got<n ){

fprintf(stderr, "got only %d of %d bytes\n", got, n);

return 1;

}else{

fwrite(zBuf, 1, n, stdout);

}

return 0;

}