114 lines
2.1 KiB
C
114 lines
2.1 KiB
C
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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main()
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{
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int fd, r, w, l;
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char buf[1024];
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char *v;
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fd = open("/dev/zero", O_RDONLY);
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if (fd < 0)
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{
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fprintf(stderr, "Unable to open /dev/zero for reading\n");
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perror("The error was");
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exit(1);
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}
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l = read(fd, buf, 1024);
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if (l != 1024)
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{
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fprintf(stderr, "Asked to read 1024 bytes, got %d\n", l);
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exit(1);
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}
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for (r=0; r<1024; r++)
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if (buf[r] != 0)
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{
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fprintf(stderr, "/dev/zero returned a byte of %02x at offset %d\n",
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buf[r], r);
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exit(1);
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}
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l = lseek(fd, 4096, 0);
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if (l != 0)
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{
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fprintf(stderr, "l == %d\n", l);
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exit(1);
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}
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l = close(fd);
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if (l != 0)
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{
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fprintf(stderr, "close: returned %d\n", l);
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perror("The error was");
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exit(1);
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}
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fd = open("/dev/zero", O_WRONLY);
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if (fd < 0)
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{
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fprintf(stderr, "Unable to open /dev/zero for writing\n");
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perror("The error was");
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exit(1);
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}
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l = write(fd, buf, 1024);
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if (l != 1024)
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{
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fprintf(stderr, "Asked to write 1024 bytes, got %d\n", l);
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exit(1);
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}
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l = close(fd);
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if (l != 0)
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{
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fprintf(stderr, "close: returned %d\n", l);
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perror("The error was");
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exit(1);
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}
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fd = open("/dev/zero", O_RDWR);
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v = (char *)mmap(0, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
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if (v == (char *)-1)
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{
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fprintf(stderr, "mmap r/w /dev/zero failed\n");
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perror("The error was");
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exit(1);
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}
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for (r=0; r<65536; r++)
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if (v[r] != 0)
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{
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fprintf(stderr, "mmap'd r/w /dev/zero has byte %d at offset %d\n",
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v[r], r);
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exit(1);
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}
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munmap(v, 65536);
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close(fd);
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fd = open("/dev/zero", O_RDONLY);
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v = (char *)mmap(0, 65536, PROT_READ, MAP_SHARED, fd, 0);
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if (v == (char *)-1)
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{
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fprintf(stderr, "mmap /dev/zero r/o failed\n");
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perror("The error was");
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exit(1);
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}
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for (r=0; r<65536; r++)
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if (v[r] != 0)
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{
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fprintf(stderr, "mmap'd r/o /dev/zero has byte %d at offset %d\n",
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v[r], r);
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exit(1);
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}
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munmap(v, 65536);
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close(fd);
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exit(0);
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}
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