From d6e503a493d2a54221531654d48a62fddc8ae9a2 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 9 Jun 2010 02:39:34 +0000
Subject: [PATCH] Attempt to fix EXPLAIN (FORMAT YAML) quoting to behave
sanely.
The previous code failed to quote in many cases where quoting was necessary -
YAML has loads of special characters, including -:[]{},"'|*& - so quote much
more aggressively, and only refrain from quoting things where it seems fairly
clear that it isn't necessary.
Per report from Dean Rasheed.
---
src/backend/commands/explain.c | 44 +++++++++++++++++++++++++++-------
1 file changed, 35 insertions(+), 9 deletions(-)
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 2409a01e2dd..d6a0f65acff 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.204 2010/02/26 02:00:39 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.205 2010/06/09 02:39:34 rhaas Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2152,22 +2152,48 @@ escape_json(StringInfo buf, const char *str)
}
/*
- * YAML is a superset of JSON: if we find quotable characters, we call
- * escape_json. If not, we emit the property unquoted for better readability.
+ * YAML is a superset of JSON, so we can use JSON escaping when escaping is
+ * needed. However, some things that need to be quoted in JSON don't require
+ * quoting in YAML, and we prefer not to quote unnecessarily, to improve
+ * readability.
+ *
+ * Unfortunately, the YAML quoting rules are ridiculously complicated -- as
+ * documented in sections 5.3 and 7.3.3 of http://yaml.org/spec/1.2/spec.html
+ * -- and it doesn't seem worth expending a large amount of energy to avoid
+ * all unnecessary quoting, so we just do something (sort of) simple: we quote
+ * any string which is empty; any string which contains characters other than
+ * alphanumerics, period, underscore, or space; or begins or ends with a
+ * space. The exception for period is mostly so that floating-point numbers
+ * (e.g., cost values) won't be quoted.
*/
static void
escape_yaml(StringInfo buf, const char *str)
{
- const char *p;
+ bool needs_quoting = false;
- for (p = str; *p; p++)
+#define is_safe_yaml(x) \
+ (isalnum(((unsigned char) x)) || (x) == '.' || (x) == '_')
+
+ if (!is_safe_yaml(str[0]))
+ needs_quoting = true;
+ else
{
- if ((unsigned char) *p < ' ' || strchr("\"\\\b\f\n\r\t", *p))
+ const char *p;
+
+ for (p = str; *p; p++)
{
- escape_json(buf, str);
- return;
+ if (*p != ' ' && !is_safe_yaml(*p))
+ {
+ needs_quoting = true;
+ break;
+ }
}
+ if (!*p && p[-1] == ' ')
+ needs_quoting = true;
}
- appendStringInfo(buf, "%s", str);
+ if (needs_quoting)
+ escape_json(buf, str);
+ else
+ appendStringInfoString(buf, str);
}
--
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