Attachment 856464 Details for Bug 1058663 – Test program to test and verify write-behind with open(), seek(), write() and mmap()

Test program to test and verify write-behind with open(), seek(), write() and mmap()

bug-1058405.c (text/plain), 2.17 KB, created by Niels de Vos on 2014-01-28 10:11:28 UTC

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Creator: Niels de Vos

Created: 2014-01-28 10:11:28 UTC

Size: 2.17 KB

patch

obsolete

>#include <stdlib.h>
>#include <stdio.h>
>#include <stdint.h>
>#include <fcntl.h>
>#include <sys/stat.h>
>#include <sys/mman.h>
>#include <signal.h>
>
>#define FILE_SIZE 1048576
>
>/* number of tests to run */
>#define RUN_LOOP 1000
>
>/* number of SIGBUS before exiting */
>#define MAX_SIGBUS 1
>static int expect_sigbus = 0;
>static int sigbus_received = 0;
>
>/* test for truncate()/seek()/write()/mmap()
> * There should ne no SIGBUS triggered.
> */
>void seek_write(char *filename)
>{
>	int fd;
>	uint8_t* map;
>	int i;
>	
>	fd = open(filename, O_RDWR|O_CREAT|O_TRUNC, 0600);
>	lseek(fd, FILE_SIZE - 1, SEEK_SET);
>	write(fd, "\xff", 1);
>
>	map = mmap(NULL, FILE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
>	for (i = 0; i < (FILE_SIZE - 1); i++) {
>		if (map[i] != 0) /* should never be true */
>			abort();
>	}
>	munmap(map, FILE_SIZE);
>
>	close(fd);
>}
>
>int read_after_eof(char *filename)
>{
>	int ret = 0;
>	int fd;
>	char* data;
>	uint8_t* map;
>	
>	fd = open(filename, O_RDWR|O_CREAT|O_TRUNC, 0600);
>	lseek(fd, FILE_SIZE - 1, SEEK_SET);
>	write(fd, "\xff", 1);
>
>	/* trigger verify that reading after EOF fails */
>	ret = read(fd, data, FILE_SIZE / 2);
>	if (ret != 0)
>		return 1;
>
>	/* map an area of 1 byte after FILE_SIZE */
>	map = mmap(NULL, 1, PROT_READ, MAP_PRIVATE, fd, FILE_SIZE);
>	/* map[0] is an access after EOF, it should trigger SIGBUS */
>	if (map[0] != 0)
>		/* it is expected that we exit before we get here */
>		if (!sigbus_received)
>			return 1;
>	munmap(map, FILE_SIZE);
>
>	close(fd);
>
>	return ret;
>}
>
>/* signal handler for SIGBUS */
>void catch_sigbus(int signum)
>{
>	switch (signum) {
>		case SIGBUS:
>			sigbus_received++;
>			if (!expect_sigbus)
>				exit(EXIT_FAILURE);
>			if (sigbus_received >= MAX_SIGBUS)
>				exit(EXIT_SUCCESS);
>			break;
>		default:
>			printf("Unexpected signal received: %d\n", signum);
>	}
>}
>
>int main(int argc, char** argv)
>{
>	int i = 0;
>
>	if (argc == 1) {
>		printf("Usage: %s <filename>\n", argv[0]);
>		return EXIT_FAILURE;
>	}
>
>	signal(SIGBUS, catch_sigbus);
>
>	/* the next test should not trigger SIGBUS */
>	expect_sigbus = 0;
>	for (i = 0; i < RUN_LOOP; i++) {
>		seek_write(argv[1]);
>	}
>
>	/* the next test should trigger SIGBUS */
>	expect_sigbus = 1;
>	if (read_after_eof(argv[1]))
>		return EXIT_FAILURE;
>
>	return EXIT_SUCCESS;
>}

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