From 0e5a63625e584bd8fc3ad4150cc8703c6f30ccdf Mon Sep 17 00:00:00 2001
From: erg <devnull@localhost>
Date: Thu, 31 Mar 2011 14:10:07 +0000
Subject: [PATCH] Fix strdup_and_subst_obj() so that calls not involving simple
 labels collapse \\ to \. Without this, users cannot get a lone backslash in
 an HTML-label or tooltip if it preceded G, E, N, etc. We don't do this for
 simple label text, as it is later processed to handle \n, \r, etc. and
 collapses \\ to \ at that time.

---
 lib/common/labels.c | 41 +++++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/lib/common/labels.c b/lib/common/labels.c
index 54f09befc..c657fe425 100644
--- a/lib/common/labels.c
+++ b/lib/common/labels.c
@@ -16,6 +16,8 @@
 #include "htmltable.h"
 #include <limits.h>
 
+static char *strdup_and_subst_obj0 (char *str, void *obj, int escBackslash);
+
 static void storeline(graph_t *g, textlabel_t *lp, char *line, char terminator)
 {
     pointf size;
@@ -165,7 +167,10 @@ textlabel_t *make_label(void *obj, char *str, int kind, double fontsize, char *f
     }
     else {
         assert(kind == LT_NONE);
-	rv->text = strdup_and_subst_obj(str, obj);
+	/* This call just processes the graph object based escape sequences. The formatting escape
+         * sequences (\n, \l, \r) are processed in make_simple_label. That call also replaces \\ with \.
+         */
+	rv->text = strdup_and_subst_obj0(str, obj, 0);
         switch (rv->charset) {
 	case CHAR_LATIN1:
 	    s = latin1ToUTF8(rv->text);
@@ -276,7 +281,13 @@ void emit_label(GVJ_t * job, emit_state_t emit_state, textlabel_t * lp)
     obj->emit_state = old_emit_state;
 }
 
-char *strdup_and_subst_obj(char *str, void *obj)
+/* strdup_and_subst_obj0:
+ * Replace various escape sequences with the name of the associated
+ * graph object. A double backslash \\ can be used to avoid a replacement.
+ * If escBackslash is true, convert \\ to \; else leave alone. All other dyads 
+ * of the form \. are passed through unchanged.
+ */
+static char *strdup_and_subst_obj0 (char *str, void *obj, int escBackslash)
 {
     char c, *s, *p, *t, *newstr;
     char *tp_str = "", *hp_str = "";
@@ -370,11 +381,12 @@ char *strdup_and_subst_obj(char *str, void *obj)
 	    case 'L':
 		newlen += l_len;
 		break; 
-#ifdef ESCAPE_BACKSLASH
 	    case '\\':
-		newlen += 1;
-		break; 
-#endif
+		if (escBackslash) {
+		    newlen += 1;
+		    break; 
+		}
+		/* Fall through */
 	    default:  /* leave other escape sequences unmodified, e.g. \n \l \r */
 		newlen += 2;
 	    }
@@ -419,11 +431,12 @@ char *strdup_and_subst_obj(char *str, void *obj)
 	    case 'L':
 		for (t = l_str; (*p = *t++); p++);
 		break;
-#ifdef ESCAPE_BACKSLASH
 	    case '\\':
-		*p++ = '\\';
-		break;
-#endif
+		if (escBackslash) {
+		    *p++ = '\\';
+		    break; 
+		}
+		/* Fall through */
 	    default:  /* leave other escape sequences unmodified, e.g. \n \l \r */
 		*p++ = '\\';
 		*p++ = c;
@@ -437,6 +450,14 @@ char *strdup_and_subst_obj(char *str, void *obj)
     return newstr;
 }
 
+/* strdup_and_subst_obj:
+ * Processes graph object escape sequences; also collapses \\ to \.
+ */
+char *strdup_and_subst_obj(char *str, void *obj)
+{
+    return strdup_and_subst_obj0 (str, obj, 1);
+}
+
 /* return true if *s points to &[A-Za-z]*;      (e.g. &Ccedil; )
  *                          or &#[0-9]*;        (e.g. &#38; )
  *                          or &#x[0-9a-fA-F]*; (e.g. &#x6C34; )
-- 
2.40.0