[src/trunk]: src/usr.bin/less/less Don't attempt to read or write ~/.lesshst ...

[dholland <dholland%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/994bab22f657
branches:  trunk
changeset: 750011:994bab22f657
user:      dholland <dholland%NetBSD.org@localhost>
date:      Mon Dec 14 03:58:27 2009 +0000

description:
Don't attempt to read or write ~/.lesshst if it's not a regular file
or a symlink to a regular file. Previously, symlinking to /dev/null
would cause less to trash /dev/null if run with sufficient privileges,
as seen in PR misc/42237.

While the official way to disable .lesshst is to set an environment
variable, that is problematic in some cases, such as single-user mode.
A safer way to prevent even an unpatched less from writing anything
out is to mkdir ~/.lesshst.

diffstat:

 usr.bin/less/less/cmdbuf.c |  27 ++++++++++++++++++++++++++-
 1 files changed, 26 insertions(+), 1 deletions(-)

diffs (63 lines):

diff -r 59228c6db368 -r 994bab22f657 usr.bin/less/less/cmdbuf.c
--- a/usr.bin/less/less/cmdbuf.c        Mon Dec 14 03:44:27 2009 +0000
+++ b/usr.bin/less/less/cmdbuf.c        Mon Dec 14 03:58:27 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cmdbuf.c,v 1.7 2006/10/26 01:33:08 mrg Exp $   */
+/*     $NetBSD: cmdbuf.c,v 1.8 2009/12/14 03:58:27 dholland Exp $      */
 
 /*
  * Copyright (C) 1984-2005  Mark Nudelman
@@ -22,6 +22,9 @@
 #if HAVE_STAT
 #include <sys/stat.h>
 #endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
 
 extern int sc_width;
 extern int utf_mode;
@@ -1362,10 +1365,20 @@
        char *filename;
        FILE *f;
        char *p;
+#ifdef HAVE_STAT
+       struct stat st;
+#endif
 
        filename = histfile_name();
        if (filename == NULL)
                return;
+#ifdef HAVE_STAT
+       /* ignore devices/fifos; allow symlinks */
+       if (stat(filename, &st) < 0)
+               return;
+       if (!S_ISREG(st.st_mode))
+               return;
+#endif
        f = fopen(filename, "r");
        free(filename);
        if (f == NULL)
@@ -1442,10 +1455,22 @@
 #if CMD_HISTORY
        char *filename;
        FILE *f;
+#ifdef HAVE_STAT
+       struct stat st;
+#endif
 
        filename = histfile_name();
        if (filename == NULL)
                return;
+#ifdef HAVE_STAT
+       /* ignore devices/fifos; allow symlinks */
+       if (stat(filename, &st) < 0) {
+               if (errno != ENOENT)
+                       return;
+       }
+       else if (!S_ISREG(st.st_mode))
+               return;
+#endif
        f = fopen(filename, "w");
        free(filename);
        if (f == NULL)