Fix lldb's macosx/heap.py cstr command

[davide]

Summary

Add a test while I'm around.
rdar://problem/44432167

[JDevlieghere]

LGTM. Thanks Davide!

[davide]

commit 44b5014ce138fa293238afeaa53cfd4c2f5b12d2 (HEAD -> master)
Author: Davide Italiano <[e-mail]>
Date: Mon Dec 17 10:23:44 2018 -0800

Fix lldb's macosx/heap.py cstr command.

<rdar://problem/44432167>

[clayborg]

nice! A lot of great commands in heap.py. Like see them fixed and improved

lldb/examples/darwin/heap_find/heap.py

     $malloc_match matches[MAX_MATCHES];
     const char *cstr;
     unsigned cstr_len;
 } callback_baton_t;
 range_callback_t range_callback = [](task_t task, void *baton, unsigned type, uintptr_t ptr_addr, uintptr_t ptr_size) -> void {
     callback_baton_t *lldb_info = (callback_baton_t *)baton;
     if (lldb_info->cstr_len < ptr_size) {
         const char *begin = (const char *)ptr_addr;
-        const char *end = begin + ptr_size - info->cstr_len;
+        const char *end = begin + ptr_size - lldb_info->cstr_len;
         for (const char *s = begin; s < end; ++s) {
             if ((int)memcmp(s, lldb_info->cstr, lldb_info->cstr_len) == 0) {
                 if (lldb_info->num_matches < MAX_MATCHES) {
                     lldb_info->matches[lldb_info->num_matches].addr = (void*)ptr_addr;
                     lldb_info->matches[lldb_info->num_matches].size = ptr_size;
                     lldb_info->matches[lldb_info->num_matches].offset = s - begin;
                     lldb_info->matches[lldb_info->num_matches].type = type;
                     ++lldb_info->num_matches;

lldb/lit/Heap/Inputs/cstr.c

+#include <stdlib.h>
+
+int main(void) {
+  char *str;
+  int size = 9; //strlen("patatino") + 1
+  str = (char *)malloc(sizeof(char)*size);
+  *(str+0) = 'p';
+  *(str+1) = 'a';
+  *(str+2) = 't';
+  *(str+3) = 'a';
+  *(str+4) = 't';
+  *(str+5) = 'i';
+  *(str+6) = 'n';
+  *(str+7) = 'o';
+  *(str+8) = '\0';
+  return 0;
+}

lldb/lit/Heap/heap-cstr.test

+# REQUIRES: system-darwin
+# RUN: %clang %p/Inputs/cstr.c -g -o %t
+# RUN: %lldb -b -s %s -f %t | FileCheck %s
+
+br set -p return
+command script import lldb.macosx.heap
+run
+cstr "patatino"
+
+# CHECK: {{.*}}: malloc(    16) -> {{.*}}