+ if (__builtin_expect (thread->stackblock != NULL, 1))
+ {
+ iattr->stacksize = thread->stackblock_size;
+ iattr->stackaddr = (char *) thread->stackblock + iattr->stacksize;
+ }
+ else
+ {
+ /* No stack information available. This must be for the initial
+ thread. Get the info in some magical way. */
+ assert (thread->pid == thread->tid);
+
+ /* Defined in ld.so. */
+ extern void *__libc_stack_end;
+
+ /* Stack size limit. */
+ struct rlimit rl;
+
+ /* The safest way to get the top of the stack is to read
+ /proc/self/maps and locate the line into which
+ __libc_stack_end falls. */
+ FILE *fp = fopen ("/proc/self/maps", "rc");
+ if (fp == NULL)
+ ret = errno;
+ /* We need the limit of the stack in any case. */
+ else if (getrlimit (RLIMIT_STACK, &rl) != 0)
+ ret = errno;
+ else
+ {
+ /* We need no locking. */
+ __fsetlocking (fp, FSETLOCKING_BYCALLER);
+
+ /* Until we found an entry (which should always be the case)
+ mark the result as a failure. */
+ ret = ENOENT;
+
+ char *line = NULL;
+ size_t linelen = 0;
+
+ while (! feof_unlocked (fp))
+ {
+ if (__getdelim (&line, &linelen, '\n', fp) <= 0)
+ break;
+
+ uintptr_t from;
+ uintptr_t to;
+ if (sscanf (line, "%" SCNxPTR "-%" SCNxPTR, &from, &to) == 2
+ && from <= (uintptr_t) __libc_stack_end
+ && (uintptr_t) __libc_stack_end < to)
+ {
+ /* Found the entry. Now we have the info we need. */
+ iattr->stacksize = rl.rlim_cur;
+ iattr->stackaddr = (void *) to;
+
+ /* We succeed and no need to look further. */
+ ret = 0;
+ break;
+ }
+ }
+
+ fclose (fp);
+ free (line);
+ }
+ }
+