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test_util: use MAP_ANONYMOUS instead of /dev/zero

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Apparently, mmap'ing /dev/zero fails on macOS.  So contrary to the
intent, it's not actually portable.  Switch to MAP_ANONYMOUS instead,
with a fallback to MAP_ANON if it's not defined.
This commit is contained in:
Eric Biggers 2019-08-30 00:14:43 -05:00
parent 2a2e24dc8b
commit f1e56f54b2
1 changed files with 18 additions and 15 deletions
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33
programs/test_util.c
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@ -25,6 +25,16 @@
* OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef _WIN32
/* for MAP_ANONYMOUS or MAP_ANON, which unfortunately aren't part of POSIX... */
# undef _POSIX_C_SOURCE
# ifdef __APPLE__
# define _DARWIN_C_SOURCE
# elif defined(__linux__)
# define _GNU_SOURCE
# endif
#endif
#include "test_util.h"
#include <fcntl.h>
@ -37,6 +47,10 @@
# include <sys/time.h>
#endif
#ifndef MAP_ANONYMOUS
# define MAP_ANONYMOUS MAP_ANON
#endif
/* Abort with an error message */
_noreturn void
assertion_failed(const char *expr, const char *file, int line)
@ -68,8 +82,6 @@ alloc_guarded_buffer(size_t size, u8 **start_ret, u8 **end_ret)
u8 *start, *end;
#ifdef _WIN32
DWORD oldProtect;
#else
int fd;
#endif
*start_ret = NULL;
@ -95,20 +107,11 @@ alloc_guarded_buffer(size_t size, u8 **start_ret, u8 **end_ret)
return -1;
}
#else
/*
* Allocate buffer and guard pages.
* For portability, use /dev/zero instead of MAP_ANONYMOUS.
*/
fd = open("/dev/zero", O_RDONLY);
if (fd < 0) {
msg_errno("Unable to open /dev/zero");
return -1;
}
base_addr = mmap(NULL, (nr_pages + 2) * pagesize,
PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
close(fd);
/* Allocate buffer and guard pages. */
base_addr = mmap(NULL, (nr_pages + 2) * pagesize, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (base_addr == (u8 *)MAP_FAILED) {
msg_errno("Unable to allocate memory (unable to mmap /dev/zero)");
msg_errno("Unable to allocate memory (anonymous mmap)");
return -1;
}
start = base_addr + pagesize;