This test program highlights the recent munmap problem addressed by Corinna.
It works with the updated mmap, and with linux, fails on cygwin with the prior mmap.
/**
* mmap test.
* mmaps two chunks of adjacent memory, then munmaps one and a half,
* then sees if the remainder is still useable.
*/
#include <unistd.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <fcntl.h>
#include <string.h>
#ifndef _POSIX_MAPPED_FILES
#warning Testing mmap/munmap, but _POSIX_MAPPED_FILES not defined.
#endif
#define CHUNKSIZE 0x10000
#undef Dim
#define Dim(x) ((int)(sizeof(x)/sizeof(x[0])))
void * mapping1,*mapping2;
char buff[CHUNKSIZE*4];
int main()
{
int fd;
int r;
int temp_open_flags;
char name[] = "test_cygwin_munmapXXXXXX";
fd = mkstemp(name);
assert(fd != -1);
temp_open_flags = fcntl(fd, F_GETFL);
assert(temp_open_flags != -1);
assert((temp_open_flags & O_RDWR) == O_RDWR);
/* Have to write to the file for mapping to work. */
r = write(fd, buff, sizeof(buff));
assert(r == sizeof(buff));
mapping1 = mmap(0, 2*CHUNKSIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
assert(mapping1 != MAP_FAILED);
mapping2 = mmap(mapping1 + 2*CHUNKSIZE, 2*CHUNKSIZE,
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED, fd,
2*CHUNKSIZE);
if(mapping2 == MAP_FAILED)
{
printf("OS wont do contiguous memory file mappings. Cant do test. Try
changing CHUNKSIZE\n");
munmap(mapping1, 2*CHUNKSIZE);
close(fd);
unlink(name);
exit(0);
}
printf("mappings: %x %x\n",mapping1,mapping2);
/* Unmap from middle of first chunk to end of second chunk. */
r = munmap(mapping1 + CHUNKSIZE, 3*CHUNKSIZE);
assert(r == 0);
/* now try setting the first half of the first chunk */
memset(mapping1, 0, CHUNKSIZE);
close(fd);
/* Unmap the last bit, so hopefully the unlink of the temporary file will
work. */
r = munmap(mapping1, CHUNKSIZE);
assert(r == 0);
r = unlink(name);
assert(r == 0);
return 0;
}
--
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