From 2371caac40766e7ab3d51669c885929135368a93 Mon Sep 17 00:00:00 2001
From: simon <simon@cda61777-01e9-0310-a592-d414129be87e>
Date: Thu, 17 May 2001 08:53:13 +0000
Subject: [PATCH] Fix the line-resizing bug in scroll(). (Thanks to RDB for
 pointing it out. A line was removed from the scrollback, cleared, and placed
 at the bottom of the screen. Fine, except that the clearing process assumed
 the line was the right length already, and thanks to lazy resizing this
 wasn't necessarily the case. Segfaults and memory corruption ensued.)

git-svn-id: svn://svn.tartarus.org/sgt/putty@1129 cda61777-01e9-0310-a592-d414129be87e
---
 terminal.c | 47 ++++++++++++++++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 15 deletions(-)

diff --git a/terminal.c b/terminal.c
index cf55f8ea..7fb20292 100644
--- a/terminal.c
+++ b/terminal.c
@@ -201,15 +201,40 @@ static FILE *lgfp = NULL;
 static void logtraffic(unsigned char c, int logmode);
 
 /*
+ * Resize a line to make it `cols' columns wide.
+ */
+unsigned long *resizeline(unsigned long *line, int cols)
+{
+    int i, oldlen;
+    unsigned long lineattrs;
+
+    if (line[0] != (unsigned long)cols) {
+	/*
+	 * This line is the wrong length, which probably means it
+	 * hasn't been accessed since a resize. Resize it now.
+	 */
+	oldlen = line[0];
+	lineattrs = line[oldlen + 1];
+	line = srealloc(line, TSIZE * (2 + cols));
+	line[0] = cols;
+	for (i = oldlen; i < cols; i++)
+	    line[i + 1] = ERASE_CHAR;
+	line[cols + 1] = lineattrs & LATTR_MODE;
+    }
+
+    return line;
+}
+
+/*
  * Retrieve a line of the screen or of the scrollback, according to
  * whether the y coordinate is non-negative or negative
  * (respectively).
  */
 unsigned long *lineptr(int y, int lineno)
 {
-    unsigned long *line, lineattrs;
+    unsigned long *line, *newline;
     tree234 *whichtree;
-    int i, treeindex, oldlen;
+    int treeindex;
 
     if (y >= 0) {
 	whichtree = screen;
@@ -223,20 +248,10 @@ unsigned long *lineptr(int y, int lineno)
     /* We assume that we don't screw up and retrieve something out of range. */
     assert(line != NULL);
 
-    if (line[0] != cols) {
-	/*
-	 * This line is the wrong length, which probably means it
-	 * hasn't been accessed since a resize. Resize it now.
-	 */
-	oldlen = line[0];
-	lineattrs = line[oldlen + 1];
+    newline = resizeline(line, cols);
+    if (newline != line) {
 	delpos234(whichtree, treeindex);
-	line = srealloc(line, TSIZE * (2 + cols));
-	line[0] = cols;
-	for (i = oldlen; i < cols; i++)
-	    line[i + 1] = ERASE_CHAR;
-	line[cols + 1] = lineattrs & LATTR_MODE;
-	addpos234(whichtree, line, treeindex);
+	addpos234(whichtree, newline, treeindex);
     }
 
     return line + 1;
@@ -568,6 +583,7 @@ static void scroll(int topline, int botline, int lines, int sb)
     if (lines < 0) {
 	while (lines < 0) {
 	    line = delpos234(screen, botline);
+            line = resizeline(line, cols);
 	    for (i = 0; i < cols; i++)
 		line[i + 1] = erase_char;
 	    line[cols + 1] = 0;
@@ -610,6 +626,7 @@ static void scroll(int topline, int botline, int lines, int sb)
 		addpos234(scrollback, line, sblen);
 		line = line2;
 	    }
+            line = resizeline(line, cols);
 	    for (i = 0; i < cols; i++)
 		line[i + 1] = erase_char;
 	    line[cols + 1] = 0;
-- 
2.11.0