190 lines
3.1 KiB
C
190 lines
3.1 KiB
C
#include <sys/types.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <setjmp.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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sigset_t unblock_sigsegv;
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jmp_buf r;
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size_t pg;
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int fd;
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/* Checks behaviour of anonymous mmap.
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test_1: If we map a 2-page region and unmap its second page, the first page
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must remain.
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test_2: If we map a 2-page region and unmap its first page, the second
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page must remain.
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test_3: If we map two consecutive 1-page regions and unmap them both with
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one munmap, both must go away.
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*/
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void
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perror_exit (char *str, int code)
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{
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printf ("%s: %s\n", str, strerror (errno));
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exit (code);
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}
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void
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anonmap_init ()
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{
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sigemptyset (&unblock_sigsegv);
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sigaddset (&unblock_sigsegv, SIGSEGV);
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pg = getpagesize ();
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fd = open ("/dev/zero", O_RDWR);
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}
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char *
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anonmap (size_t size)
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{
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return (char *) mmap (0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
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}
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void
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anonfree (char *loc, size_t size)
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{
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munmap (loc, size);
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}
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void
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sigsegv (int unused)
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{
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sigprocmask (SIG_UNBLOCK, &unblock_sigsegv, 0);
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longjmp (r, 1);
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}
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int
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compare_pointers (const void *a, const void *b)
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{
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const char *x = *(const char *const *)a;
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const char *y = *(const char *const *)b;
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if (x > y)
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return 1;
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if (x < y)
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return -1;
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return 0;
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}
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void
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test_1 ()
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{
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char *x = anonmap (pg * 2);
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if (x == (char *)MAP_FAILED)
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perror_exit ("test 1 mmap", 1);
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signal (SIGSEGV, sigsegv);
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if (setjmp (r))
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perror_exit ("test 1 fault", 2);
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x[0] = 1;
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x[pg] = 1;
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anonfree (x + pg, pg);
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x[0] = 2;
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if (setjmp (r) == 0)
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{
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x[pg] = 1;
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perror_exit ("test 1 no fault", 3);
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}
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}
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void
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test_2 ()
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{
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char *x = anonmap (pg * 2);
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if (x == (char *)MAP_FAILED)
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perror_exit ("test 2 mmap", 4);
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signal (SIGSEGV, sigsegv);
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if (setjmp (r))
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perror_exit ("test 2 fault", 5);
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x[0] = 1;
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x[pg] = 1;
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anonfree (x, pg);
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x[pg] = 2;
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if (setjmp (r) == 0)
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{
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x[0] = 1;
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perror_exit ("test 2 no fault", 6);
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}
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}
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void
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test_3 ()
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{
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char *x[10];
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char *y;
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int i;
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/* There's no way to guarantee we get consecutive pages from the OS. The
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approach taken here is to allocate ten of them, sort the list, and
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look for consecutive pages. */
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for (i = 0; i < 10; i++)
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{
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x[i] = anonmap (pg);
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if (x[i] == (char *)MAP_FAILED)
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perror_exit ("test 3 mmap 1", 7);
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}
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qsort (x, 10, sizeof (char *), compare_pointers);
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y = 0;
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for (i = 0; i < 9; i++)
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if (x[i] + pg == x[i+1])
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{
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y = x[i];
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break;
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}
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if (y == 0)
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{
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fputs ("test 3: couldn't get two consecutive pages, giving up\n", stdout);
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exit (65);
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}
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signal (SIGSEGV, sigsegv);
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if (setjmp (r))
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perror_exit ("test 3 fault", 8);
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y[0] = 1;
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y[pg] = 1;
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anonfree (y, pg * 2);
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if (setjmp (r) == 0)
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{
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y[0] = 1;
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perror_exit ("test 3 no fault 1", 9);
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}
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signal (SIGSEGV, sigsegv);
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if (setjmp (r) == 0)
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{
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y[pg] = 1;
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perror_exit ("test 3 no fault 2", 10);
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}
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}
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int
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main ()
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{
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anonmap_init();
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test_1();
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test_2();
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test_3();
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exit(0);
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}
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