[lldb] Improve meta data stripping from JSON crashlogs

lldb/examples/python/crashlog.py

@@ -415,8 +415,14 @@ def parse(self):
         with open(self.path, 'r') as f:
             buffer = f.read()
 
-        # First line is meta-data.
-        buffer = buffer[buffer.index('\n') + 1:]
+        # Skip the first line if it contains meta data.
+        head, _, tail = buffer.partition('\n')
+        try:
+            metadata = json.loads(head)
+            if 'app_name' in metadata and 'app_version' in metadata:
+                buffer = tail
+        except ValueError:
+            pass
 
         try:
             self.data = json.loads(buffer)

lldb/test/Shell/ScriptInterpreter/Python/Crashlog/json.test

@@ -1,8 +1,13 @@
 # RUN: %clang_host -g %S/Inputs/test.c -o %t.out
+
 # RUN: cp %S/Inputs/a.out.ips %t.crash
 # RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}' --json
 # RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.crash' 2>&1 | FileCheck %s
 
+# RUN: cp %S/Inputs/a.out.ips %t.nometadata.crash
+# RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.nometadata.crash --offsets '{"main":20, "bar":9, "foo":16}' --json --no-metadata
+# RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.nometadata.crash' 2>&1 | FileCheck %s
+
 # CHECK: Thread[0] Crashing Thread Name EXC_BAD_ACCESS (SIGSEGV) (KERN_INVALID_ADDRESS at 0x0000000000000000)
 # CHECK: [  0] {{.*}}out`foo + 16 at test.c
 # CHECK: [  1] {{.*}}out`bar + 8 at test.c

lldb/test/Shell/ScriptInterpreter/Python/Crashlog/patch-crashlog.py

@@ -49,13 +49,17 @@ def patch_addresses(self):
                     self.data = self.data.replace(
                         "@{}@".format(symbol), str(representation(patch_addr)))
 
+    def remove_metadata(self):
+        self.data= self.data[self.data.index('\n') + 1:]
+
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(description='Crashlog Patcher')
     parser.add_argument('--binary', required=True)
     parser.add_argument('--crashlog', required=True)
     parser.add_argument('--offsets', required=True)
     parser.add_argument('--json', default=False, action='store_true')
+    parser.add_argument('--no-metadata', default=False, action='store_true')
     args = parser.parse_args()
 
     offsets = json.loads(args.offsets)
@@ -68,5 +72,8 @@ def patch_addresses(self):
     p.patch_uuid()
     p.patch_addresses()
 
+    if args.no_metadata:
+        p.remove_metadata()
+
     with open(args.crashlog, 'w') as file:
         file.write(p.data)