virsh: Clarify escape sequence

Currently, we put no strains on escape sequence possibly leaving users
with console that cannot be terminated. However, not all ASCII
characters can be used as escape sequence. Only those falling in
@ - _ can be; implement and document this constraint.

diff --git a/tools/console.c b/tools/console.c
index ca226c3356fc958d89e3d300fad11019a12d6f33..34fde05eb707821058cffa3787d3ad45b1ca6488 100644 (file)
--- a/tools/console.c
+++ b/tools/console.c
@@ -34,6 +34,7 @@
 # include <errno.h>
 # include <unistd.h>
 # include <signal.h>
+# include <c-ctype.h>
 
 # include "internal.h"
 # include "console.h"
@@ -292,7 +293,7 @@ static char
 vshGetEscapeChar(const char *s)
 {
     if (*s == '^')
-        return CONTROL(s[1]);
+        return CONTROL(c_toupper(s[1]));
 
     return *s;
 }

diff --git a/tools/virsh.c b/tools/virsh.c
index 1ed2ddaae61235ed5d9d9dcf45d9f341fedc22fe..cfdd040b5e03e271e0f5cad981dc7eb13918d623 100644 (file)
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -19879,6 +19879,16 @@ vshShowVersion(vshControl *ctl ATTRIBUTE_UNUSED)
     vshPrint(ctl, "\n");
 }
 
+static bool
+vshAllowedEscapeChar(char c)
+{
+    /* Allowed escape characters:
+     * a-z A-Z @ [ \ ] ^ _
+     */
+    return ('a' <= c && c <= 'z') ||
+        ('@' <= c && c <= '_');
+}
+
 /*
  * argv[]:  virsh [options] [command]
  *
@@ -19942,7 +19952,8 @@ vshParseArgv(vshControl *ctl, int argc, char **argv)
         case 'e':
             len = strlen(optarg);
 
-            if ((len == 2 && *optarg == '^') ||
+            if ((len == 2 && *optarg == '^' &&
+                 vshAllowedEscapeChar(optarg[1])) ||
                 (len == 1 && *optarg != '^')) {
                 ctl->escapeChar = optarg;
             } else {

diff --git a/tools/virsh.pod b/tools/virsh.pod
index d4971a32cb48c86a7fb054a2d533079f3c157e91..a60e66770adace36ba532b92376c9046e6055d4c 100644 (file)
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -95,7 +95,8 @@ Output elapsed time information for each command.
 =item B<-e>, B<--escape> I<string>
 
 Set alternative escape sequence for I<console> command. By default,
-telnet's B<^]> is used.
+telnet's B<^]> is used. Allowed characters when using hat notation are:
+alphabetic character, @, [, ], \, ^, _.
 
 =back