47 lines
856 B
C
47 lines
856 B
C
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/*
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** Extract a range of bytes from a file.
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**
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** Usage:
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**
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** extract FILENAME OFFSET AMOUNT
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**
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** The bytes are written to standard output.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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int main(int argc, char **argv){
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FILE *f;
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char *zBuf;
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int ofst;
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int n;
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size_t got;
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if( argc!=4 ){
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fprintf(stderr, "Usage: %s FILENAME OFFSET AMOUNT\n", *argv);
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return 1;
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}
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f = fopen(argv[1], "rb");
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if( f==0 ){
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fprintf(stderr, "cannot open \"%s\"\n", argv[1]);
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return 1;
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}
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ofst = atoi(argv[2]);
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n = atoi(argv[3]);
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zBuf = malloc( n );
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if( zBuf==0 ){
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fprintf(stderr, "out of memory\n");
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return 1;
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}
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fseek(f, ofst, SEEK_SET);
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got = fread(zBuf, 1, n, f);
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fclose(f);
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if( got<n ){
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fprintf(stderr, "got only %d of %d bytes\n", got, n);
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return 1;
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}else{
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fwrite(zBuf, 1, n, stdout);
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}
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return 0;
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}
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