From cc0e4c5670083feecdfd1dff0abfb9a685462c15 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 20 Oct 2016 17:17:50 -0400 Subject: [PATCH] Fix EXPLAIN so that it doesn't emit invalid XML in corner cases. With track_io_timing = on, EXPLAIN (ANALYZE, BUFFERS) will emit fields named like "I/O Read Time". The slash makes that invalid as an XML element name, so that adding FORMAT XML would produce invalid XML. We already have code in there to translate spaces to dashes, so let's generalize that to convert anything that isn't a valid XML name character, viz letters, digits, hyphens, underscores, and periods. We could just reject slashes, which would run a bit faster. But the fact that this went unnoticed for so long doesn't give me a warm feeling that we'd notice the next creative violation, so let's make it a permanent fix. Reported by Markus Winand, though this isn't his initial patch proposal. Back-patch to 9.2 where track_io_timing was added. The problem is only latent in 9.1, so I don't feel a need to fix it there. Discussion: --- src/backend/commands/explain.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 11047f7982..b57eab752a 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -3190,13 +3190,15 @@ ExplainSeparatePlans(ExplainState *es) * Optionally, OR in X_NOWHITESPACE to suppress the whitespace we'd normally * add. * - * XML tag names can't contain white space, so we replace any spaces in - * "tagname" with dashes. + * XML restricts tag names more than our other output formats, eg they can't + * contain white space or slashes. Replace invalid characters with dashes, + * so that for example "I/O Read Time" becomes "I-O-Read-Time". */ static void ExplainXMLTag(const char *tagname, int flags, ExplainState *es) { const char *s; + const char *valid = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_."; if ((flags & X_NOWHITESPACE) == 0) appendStringInfoSpaces(es->str, 2 * es->indent); @@ -3204,7 +3206,7 @@ ExplainXMLTag(const char *tagname, int flags, ExplainState *es) if ((flags & X_CLOSING) != 0) appendStringInfoCharMacro(es->str, '/'); for (s = tagname; *s; s++) - appendStringInfoCharMacro(es->str, (*s == ' ') ? '-' : *s); + appendStringInfoChar(es->str, strchr(valid, *s) ? *s : '-'); if ((flags & X_CLOSE_IMMEDIATE) != 0) appendStringInfoString(es->str, " /"); appendStringInfoCharMacro(es->str, '>');