50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
#include <err.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/eventfd.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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int efd;
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uint64_t u;
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ssize_t s;
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if (argc < 2) {
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fprintf(stderr, "Usage: %s <num>...\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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efd = eventfd(0, 0);
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if (efd == -1)
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err(EXIT_FAILURE, "eventfd");
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switch (fork()) {
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case 0:
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for (size_t j = 1; j < argc; j++) {
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printf("Child writing %s to efd\n", argv[j]);
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u = strtoull(argv[j], NULL, 0);
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/* strtoull() allows various bases */
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s = write(efd, &u, sizeof(uint64_t));
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if (s != sizeof(uint64_t))
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err(EXIT_FAILURE, "write");
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}
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printf("Child completed write loop\n");
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exit(EXIT_SUCCESS);
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default:
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sleep(2);
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printf("Parent about to read\n");
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s = read(efd, &u, sizeof(uint64_t));
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if (s != sizeof(uint64_t))
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err(EXIT_FAILURE, "read");
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printf("Parent read %" PRIu64 " (%#" PRIx64 ") from efd\n", u, u);
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exit(EXIT_SUCCESS);
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case -1:
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err(EXIT_FAILURE, "fork");
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}
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} |