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nptl: Use uintptr_t for address diagnostic in nptl/tst-pthread-getattr

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Recent GCC versions warn about the attempt to return the address of a
local variable:

tst-pthread-getattr.c: In function ‘allocate_and_test’:
tst-pthread-getattr.c:54:10: error: function returns address of local variable [-Werror=return-local-addr]
   54 |   return mem;
      |          ^~~
In file included from ../include/alloca.h:3,
                 from tst-pthread-getattr.c:26:
../stdlib/alloca.h:35:23: note: declared here
   35 | # define alloca(size) __builtin_alloca (size)
      |                       ^~~~~~~~~~~~~~~~~~~~~~~
tst-pthread-getattr.c:51:9: note: in expansion of macro ‘alloca’
   51 |   mem = alloca ((size_t) (mem - target));
      |         ^~~~~~

The address itself is used in a check in the caller, so using
uintptr_t instead is reasonable.
This commit is contained in:
Florian Weimer 2019-07-30 10:35:08 +02:00
parent b8b3d5a14e
commit 8a814e20d4
2 changed files with 15 additions and 8 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2019-07-30 Florian Weimer <fweimer@redhat.com>
* nptl/tst-pthread-getattr.c (allocate_and_test): Change return
type to uintptr_t. Update comment.
(check_stack_top): Adjust.
2019-07-29 Florian Weimer <fweimer@redhat.com> 2019-07-29 Florian Weimer <fweimer@redhat.com>
Linux: Move declaration of getdents64 to <dirent.h>. Linux: Move declaration of getdents64 to <dirent.h>.

17
nptl/tst-pthread-getattr.c
View File

@ -41,9 +41,11 @@
static size_t pagesize; static size_t pagesize;
/* Check if the page in which TARGET lies is accessible. This will segfault /* Test that the page in which TARGET lies is accessible. This will
if it fails. */ segfault if the write fails. This function has only half a page
static volatile char * of thread stack left and so should not do anything and immediately
return the address to which the stack reached. */
static volatile uintptr_t
allocate_and_test (char *target) allocate_and_test (char *target)
{ {
volatile char *mem = (char *) &mem; volatile char *mem = (char *) &mem;
@ -51,7 +53,7 @@ allocate_and_test (char *target)
mem = alloca ((size_t) (mem - target)); mem = alloca ((size_t) (mem - target));
*mem = 42; *mem = 42;
return mem; return (uintptr_t) mem;
} }
static int static int
@ -84,7 +86,6 @@ check_stack_top (void)
{ {
struct rlimit stack_limit; struct rlimit stack_limit;
void *stackaddr; void *stackaddr;
volatile void *mem;
size_t stacksize = 0; size_t stacksize = 0;
int ret; int ret;
uintptr_t pagemask = ~(pagesize - 1); uintptr_t pagemask = ~(pagesize - 1);
@ -130,14 +131,14 @@ check_stack_top (void)
stack and test access there. It is however sufficient to simply check if stack and test access there. It is however sufficient to simply check if
the top page is accessible, so we target our access halfway up the top the top page is accessible, so we target our access halfway up the top
page. Thanks Chris Metcalf for this idea. */ page. Thanks Chris Metcalf for this idea. */
mem = allocate_and_test (stackaddr + pagesize / 2); uintptr_t mem = allocate_and_test (stackaddr + pagesize / 2);
/* Before we celebrate, make sure we actually did test the same page. */ /* Before we celebrate, make sure we actually did test the same page. */
if (((uintptr_t) stackaddr & pagemask) != ((uintptr_t) mem & pagemask)) if (((uintptr_t) stackaddr & pagemask) != (mem & pagemask))
{ {
printf ("We successfully wrote into the wrong page.\n" printf ("We successfully wrote into the wrong page.\n"
"Expected %#" PRIxPTR ", but got %#" PRIxPTR "\n", "Expected %#" PRIxPTR ", but got %#" PRIxPTR "\n",
(uintptr_t) stackaddr & pagemask, (uintptr_t) mem & pagemask); (uintptr_t) stackaddr & pagemask, mem & pagemask);
return 1; return 1;
} }