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/*
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 * Given a filename, outputs a 32bit key for use in 
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 * context keyed payload encoding. The key is derived from
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 * XOR-ing the st_size and st_mtime fields of the
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 * relevant struct stat for this file.
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 *
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 * Author: Dimitris Glynos <dimitris at census-labs.com>
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 */
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#include <stdio.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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int main(int argc, char *argv[])
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{
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	char *filename;
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	struct stat stat_buf;
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	if (argc != 2) {
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		fprintf(stderr, "usage: %s <filename>\n", argv[0]);
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		return 1;
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	}
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	filename = argv[1];
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	if (stat(filename, &stat_buf) == -1) {
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		perror("error while stat(2)-ing file");
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		return 1;
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	} 	
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	printf("%#.8lx\n", stat_buf.st_mtime ^ stat_buf.st_size);
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	return 0;
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}
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