Re: Segmentation fault in notmuch search --format=json

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+From: Mark Walters <markwalters1009@gmail.com>\r
+To: Ben Gamari <bgamari.foss@gmail.com>, notmuch@notmuchmail.org\r
+Subject: Re: Segmentation fault in notmuch search --format=json\r
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+\r
+On Tue, 07 Aug 2012, Ben Gamari <bgamari.foss@gmail.com> wrote:\r
+> It seems some messages trigger a segmentation fault in\r
+> `do_search_threads()`. It appears the problem occurs (at least) when\r
+> `authors` is NULL.\r
+\r
+Hi thanks for the bug report and detailed debugging. I think I can see\r
+the problem and there is a test patch to fix it below, and this does\r
+appear to be a regression.\r
+\r
+In json.c the function json_quote_str explicitly checks/allows for a\r
+NULL pointer passed as a string and pretends it is just an empty\r
+string. That behaviour was lost in the move to structured formatters.\r
+\r
+A simple fix is to put this check for a null pointer in json_string in\r
+sprinter-json.c which is what this patch does.\r
+\r
+Incidentally this is the second time this bug has appeared: \r
+\r
+        commit cacefbf3d6dd5bce0b60b3cdfce29bfa371dfaea\r
+        Author: David Edmondson <dme@dme.org>\r
+        Date:   Tue Apr 6 08:24:00 2010 +0100\r
+\r
+            json: Avoid calling strlen(NULL)\r
+                \r
+                    MIME parts may have no filename, which previously resulted in calling\r
+                        strlen(NULL).\r
+\r
+so it really might be worth having a test for it!\r
+\r
+Finally, I think nothing in json.c is used anymore so perhaps it\r
+ could be removed.\r
+\r
+\r
+diff --git a/sprinter-json.c b/sprinter-json.c\r
+index c9b6835..0a07790 100644\r
+--- a/sprinter-json.c\r
++++ b/sprinter-json.c\r
+@@ -118,6 +118,8 @@ json_string_len (struct sprinter *sp, const char *val, size_t len)\r
+ static void\r
+ json_string (struct sprinter *sp, const char *val)\r
+ {\r
++    if (val == NULL)\r
++      val = "";\r
+     json_string_len (sp, val, strlen (val));\r
+ }\r
+ \r
+\r