From: Fletcher T. Penney <fletcher@fletcherpenney.net>
Date: Sun, 29 Jan 2017 13:33:39 +0000 (-0500)
Subject: FIXED: Avoid pathologic slowdown on nested brackets
X-Git-Tag: 0.1.2a^2~18
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5b38ea2874af4c16a1a1917b8297e2416cd5b2a9;p=multimarkdown

FIXED: Avoid pathologic slowdown on nested brackets
---

diff --git a/src/writer.c b/src/writer.c
index f5b847b..9b60658 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -1160,11 +1160,29 @@ void parse_brackets(const char * source, scratch_pad * scratch, token * bracket,
 		temp_char = text_inside_pair(source, next);
 
 		if (temp_char[0] == '\0') {
-			// Empty label, use first bracket
+			// Empty label, use first bracket (e.g. implicit link `[foo][]`)
 			free(temp_char);
 			temp_char = text_inside_pair(source, bracket);
 		}
 	} else {
+		// This may be a simplified implicit link, e.g. `[foo]`
+
+		// But not if it's nested brackets, since it would not
+		// end up being a valid reference
+		token * walker = bracket->child;
+		while (walker) {
+			switch (walker->type) {
+				case PAIR_BRACKET:
+				case PAIR_BRACKET_CITATION:
+				case PAIR_BRACKET_FOOTNOTE:
+				case PAIR_BRACKET_VARIABLE:
+					*final_link = NULL;
+					return;
+			}
+
+			walker = walker->next;
+		}
+
 		temp_char = text_inside_pair(source, bracket);
 		// Don't skip tokens
 		temp_short = 0;
diff --git a/tools/pathological_tests.sh b/tools/pathological_tests.sh
index 329f25d..72402c0 100755
--- a/tools/pathological_tests.sh
+++ b/tools/pathological_tests.sh
@@ -76,17 +76,15 @@ echo "**x <a href=\"d\">*b**c*</a></p>" >>	path8.html
 
 
 # Nested brackets
-# TODO: Performance hit between 1000 and 10,000 iterations
-# Checking each level to see if it's a valid link on the stack
-# seq -s " " -f "[" $X >				path9.text
-# echo -n "a" >> 						path9.text
-# seq -s " " -f "]" $X >>				path9.text
-# 
-# echo -n "<p>" >						path9.html
-# seq -s " " -f "[" $X >>				path9.html
-# echo -n "a" >> 						path9.html
-# seq -s " " -f "]" $Y >>				path9.html
-# echo "]</p>" >>						path9.html
+seq -s " " -f "[" $X >				path9.text
+echo -n "a" >> 						path9.text
+seq -s " " -f "]" $X >>				path9.text
+
+echo -n "<p>" >						path9.html
+seq -s " " -f "[" $X >>				path9.html
+echo -n "a" >> 						path9.html
+seq -s " " -f "]" $Y >>				path9.html
+echo "]</p>" >>						path9.html
 
 
 # Nested block quotes