62 lines
1.2 KiB
C
62 lines
1.2 KiB
C
/*
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** CHECKSUM.C - Compute the checksum of a file
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**
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** public somain demo by Bob Stout
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*/
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#include <stdlib.h>
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#include "checksum.h"
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unsigned
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checksum(void *buffer, size_t len, unsigned int seed)
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{
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unsigned char *buf = (unsigned char *)buffer;
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size_t i;
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for (i = 0; i < len; ++i)
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seed += (unsigned int)(*buf++);
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return seed;
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}
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unsigned
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checksum_fp(FILE *fp)
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{
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unsigned int seed = 0;
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char buf[4096];
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size_t len;
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do {
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len = fread(buf, sizeof(char), sizeof(buf), fp);
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seed = checksum(buf, len, seed);
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} while (len > 0);
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return seed;
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}
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#ifdef EXECUTABLE
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#include <stdio.h>
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int main(int argc, char *argv[])
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{
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FILE *fp;
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const char *file;
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if (argc < 2) {
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printf("You need to provide an input file\n");
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printf("Example: %s <file>", argv[0]);
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}
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file = argv[1];
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if (NULL == (fp = fopen(file, "rb")))
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{
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printf("Unable to open %s for reading\n", file);
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return -1;
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}
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printf("The checksum of %s is %#x\n", file, checksum_fp(fp));
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return 0;
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}
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#endif
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