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@@ -0,0 +1,39 @@
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+/*
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License,
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+ * version 2 as published by the Free Software Foundation.
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+ *
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+ * (C) John Crispin <[email protected]>
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+ */
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+
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+#include <sys/types.h>
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+#include <sys/stat.h>
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+#include <fcntl.h>
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+#include <stdio.h>
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+#include <stdint.h>
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+#include <unistd.h>
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+#include <errno.h>
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+
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+int main(int argc, char **argv)
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+{
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+ uint32_t t = 0, sum = 0x55aa55aa;
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+ int fd;
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+
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+ if ((argc != 2) || ((fd = open(argv[1], O_RDWR)) == -1)) {
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+ fprintf(stderr, "Usage: %s input_file\n", *argv);
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+ return -EINVAL;
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+ }
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+
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+ lseek(fd, -4, SEEK_END);
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+ write(fd, &t, 4);
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+ lseek(fd, 0, SEEK_SET);
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+
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+ while (read(fd, &t, 4) > 0)
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+ sum -= t;
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+
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+ lseek(fd, -4, SEEK_END);
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+ write(fd, &sum, 4);
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+ close(fd);
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+
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+ return 0;
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+}
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