From 00ec2fd2dba6306edacdf5b69f099912226a32d2 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Sat, 10 Mar 2018 23:04:25 -0800
Subject: [PATCH 1/4] Add heapfrom command

---
 commands/FBDebugCommands.py | 42 +++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/commands/FBDebugCommands.py b/commands/FBDebugCommands.py
index 9afe6d7..459e2f9 100644
--- a/commands/FBDebugCommands.py
+++ b/commands/FBDebugCommands.py
@@ -380,6 +380,48 @@ def chiselLibraryPath(self):
     return os.path.join(source_dir, '..', '..', 'lib', 'Chisel.framework', 'Chisel')
 
 
+class FBHeapFromCommand(fb.FBCommand):
+  def name(self):
+    return 'heapfrom'
+
+  def description(self):
+    return 'Show all nested heap pointers contained within a given variable.'
+
+  def run(self, arguments, options):
+    # This command is like `expression --synthetic-type false`, except only showing nested heap references.
+    var = self.context.frame.var(arguments[0])
+    # Use the actual underlying structure of the variable, not the human friendly (synthetic) one.
+    root = var.GetNonSyntheticValue()
+
+    # Traversal of SBValue tree to get leaf nodes, which is where heap pointers will be.
+    leafs = []
+    queue = [root]
+    while queue:
+        node = queue.pop(0)
+        if node.num_children == 0:
+            leafs.append(node)
+        else:
+            queue += [node.GetChildAtIndex(i) for i in range(node.num_children)]
+
+    pointers = {}
+    for node in leafs:
+        # Assumption: an addr that has no value means a pointer.
+        if node.addr and not node.value:
+            pointers[node.load_addr] = node.path
+
+    options = lldb.SBExpressionOptions()
+    options.SetLanguage(lldb.eLanguageTypeC)
+    def isHeap(addr):
+        lookup = '(int)malloc_size({})'.format(addr)
+        return self.context.frame.EvaluateExpression(lookup, options).unsigned != 0
+
+    allocations = (addr for addr in pointers if isHeap(addr))
+    for addr in allocations:
+        print >>self.result, '0x{addr:x}: {path}'.format(addr=addr, path=pointers[addr])
+    if not allocations:
+        print >>self.result, "No heap addresses found"
+
+
 class FBSequenceCommand(fb.FBCommand):
   def name(self):
     return 'sequence'

From a99f6634f3b20af684ff72257b234cc69ce251f1 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Sat, 10 Mar 2018 23:12:37 -0800
Subject: [PATCH 2/4] Export heapfrom command

---
 commands/FBDebugCommands.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/commands/FBDebugCommands.py b/commands/FBDebugCommands.py
index 459e2f9..0c06923 100644
--- a/commands/FBDebugCommands.py
+++ b/commands/FBDebugCommands.py
@@ -17,6 +17,7 @@ def lldbcommands():
     FBFindInstancesCommand(),
     FBMethodBreakpointEnableCommand(),
     FBMethodBreakpointDisableCommand(),
+    FBHeapFromCommand(),
     FBSequenceCommand(),
   ]
 

From 30997628f7692bda907995e5a67dd9e883dee2f4 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Sat, 10 Mar 2018 23:21:30 -0800
Subject: [PATCH 3/4] Add heapfrom input validity check

---
 commands/FBDebugCommands.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/commands/FBDebugCommands.py b/commands/FBDebugCommands.py
index 0c06923..9816ed5 100644
--- a/commands/FBDebugCommands.py
+++ b/commands/FBDebugCommands.py
@@ -391,6 +391,10 @@ def description(self):
   def run(self, arguments, options):
     # This command is like `expression --synthetic-type false`, except only showing nested heap references.
     var = self.context.frame.var(arguments[0])
+    if not var or not var.IsValid():
+      self.result.SetError('No variable named "{}"'.format(arguments[0]))
+      return
+
     # Use the actual underlying structure of the variable, not the human friendly (synthetic) one.
     root = var.GetNonSyntheticValue()
 

From ff3c25276163f75ac534779d543088e80e3e42d2 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Sun, 11 Mar 2018 14:40:01 -0700
Subject: [PATCH 4/4] Remove : after memory address

---
 commands/FBDebugCommands.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/commands/FBDebugCommands.py b/commands/FBDebugCommands.py
index 9816ed5..751ddf2 100644
--- a/commands/FBDebugCommands.py
+++ b/commands/FBDebugCommands.py
@@ -422,7 +422,7 @@ def isHeap(addr):
 
     allocations = (addr for addr in pointers if isHeap(addr))
     for addr in allocations:
-        print >>self.result, '0x{addr:x}: {path}'.format(addr=addr, path=pointers[addr])
+        print >>self.result, '0x{addr:x} {path}'.format(addr=addr, path=pointers[addr])
     if not allocations:
         print >>self.result, "No heap addresses found"