Move the last remaining tests out of corecheck.

Also introduced VG_(showing_core_errors)() to make core error display
more consistent.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@4073

memcheck/tests/stack_changes.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <ucontext.h>
+
+#include "valgrind.h"
+
+#define STACK_SIZE 4096
+
+struct ucontext ctx1, ctx2, oldc;
+int count;
+
+void hello(struct ucontext *newc)
+{
+    printf("hello, world: %d\n", count);
+    if (count++ == 2)
+        newc = &oldc;
+    setcontext(newc);
+}
+
+int init_context(struct ucontext *uc)
+{
+    void *stack;
+    int ret;
+
+    if (getcontext(uc) == -1) {
+        perror("getcontext");
+        exit(1);
+    }
+
+    if ((stack = malloc(STACK_SIZE)) == NULL) {
+        perror("malloc");
+        exit(1);
+    }
+
+    ret = VALGRIND_STACK_REGISTER(stack, stack + STACK_SIZE);
+
+    uc->uc_link = NULL;
+    uc->uc_stack.ss_sp = stack;
+    uc->uc_stack.ss_size = STACK_SIZE;
+    uc->uc_stack.ss_flags = 0;
+
+    return ret;
+}
+
+int main(int argc, char **argv)
+{
+    int c1 = init_context(&ctx1);
+    int c2 = init_context(&ctx2);
+
+    makecontext(&ctx1, (void (*)()) hello, 2, &ctx2);
+    makecontext(&ctx2, (void (*)()) hello, 2, &ctx1);
+
+    swapcontext(&oldc, &ctx1);
+
+    VALGRIND_STACK_DEREGISTER(c1);
+    free(ctx1.uc_stack.ss_sp);
+    VALGRIND_STACK_DEREGISTER(c2);
+    free(ctx2.uc_stack.ss_sp);
+
+    return 0;
+}