gdb/testsuite: check mmap ret val against MAP_FAILED

Fixup a few spots in the testsuite that use mmap to consistently check
the return value against MAP_FAILED.

One spot in gdb.base/coredump-filter.c checked against NULL, that is
wrong.  The other spots either didn't check, or checked against -1.
MAP_FAILED has the value -1, at least on Linux, but it's better to check
against the documented define.

gdb/testsuite/ChangeLog:

	PR gdb/26016
	* gdb.base/coredump-filter.c (do_mmap): Check mmap ret val
	against MAP_FAILED.
	* gdb.base/coremaker.c (mmapdata): Likewise.
	* gdb.base/jit-reader-host.c (main): Likewise.
	* gdb.base/sym-file-loader.c (load): Likewise.
	(load_shlib): Likewise.

1 files changed, 4 insertions, 1 deletions

diff --git a/gdb/testsuite/gdb.base/sym-file-loader.c b/gdb/testsuite/gdb.base/sym-file-loader.c
index 5fcabec..c8074b8 100644
--- a/gdb/testsuite/gdb.base/sym-file-loader.c
+++ b/gdb/testsuite/gdb.base/sym-file-loader.c
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
+#include <assert.h>
 
 #include "sym-file-loader.h"
 
@@ -112,6 +113,8 @@ load (uint8_t *addr, Elf_External_Phdr *phdr, struct segment *tail_seg)
   mapped_addr = (uint8_t *) mmap ((void *) GETADDR (phdr, p_vaddr),
 				  GET (phdr, p_memsz), perm,
 				  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  assert (mapped_addr != MAP_FAILED);
+
   mapped_size = GET (phdr, p_memsz);
 
   from = (void *) (addr + GET (phdr, p_offset));
@@ -255,7 +258,7 @@ load_shlib (const char *file)
     }
 
   addr = (uint8_t *) mmap (NULL, fsize, PROT_READ, MAP_PRIVATE, fd, 0);
-  if (addr == (uint8_t *) -1)
+  if (addr == MAP_FAILED)
     {
       perror ("mmap failed.");
       return NULL;