svn commit: r345953 - stable/12/usr.bin/top

[Dimitry Andric]

Author: dim
Date: Fri Apr  5 16:12:31 2019
New Revision: 345953
URL: https://svnweb.freebsd.org/changeset/base/345953

Log:
  MFC r345807:
  
  Fix regression in top(1) after r344381, causing informational messages
  to no longer be displayed.  This was because the reimplementation of
  setup_buffer() did not copy the previous contents into any reallocated
  buffer.
  
  Reported by:	James Wright <james.wright at jigsawdezign.com>
  PR:		236947

Modified:
  stable/12/usr.bin/top/display.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/usr.bin/top/display.c
==============================================================================
--- stable/12/usr.bin/top/display.c	Fri Apr  5 16:09:23 2019	(r345952)
+++ stable/12/usr.bin/top/display.c	Fri Apr  5 16:12:31 2019	(r345953)
@@ -1347,7 +1347,8 @@ i_uptime(struct timeval *bt, time_t *tod)
 static char *
 setup_buffer(char *buffer, int addlen)
 {
-    size_t len;
+    size_t len, old_len;
+    char *new_buffer;
 
     setup_buffer_bufsiz = screen_width;
     if (setup_buffer_bufsiz < SETUPBUFFER_MIN_SCREENWIDTH)
@@ -1355,13 +1356,18 @@ setup_buffer(char *buffer, int addlen)
 	setup_buffer_bufsiz = SETUPBUFFER_MIN_SCREENWIDTH;
     }
 
-    free(buffer);
     len = setup_buffer_bufsiz + addlen + SETUPBUFFER_REQUIRED_ADDBUFSIZ;
-    buffer = calloc(len, sizeof(char));
-    if (buffer == NULL)
+    new_buffer = calloc(len, sizeof(char));
+    if (new_buffer == NULL)
     {
 	errx(4, "can't allocate sufficient memory");
     }
+    if (buffer != NULL)
+    {
+	old_len = strlen(buffer);
+	memcpy(new_buffer, buffer, old_len < len - 1 ? old_len : len - 1);
+	free(buffer);
+    }
 
-    return buffer;
+    return new_buffer;
 }