sed: fix a command with multible trailing backslashes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

editors/sed.c

@@ -487,7 +487,7 @@ static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
 static void add_cmd(const char *cmdstr)
 {
 	sed_cmd_t *sed_cmd;
-	int temp;
+	unsigned len, n;
 
 	/* Append this line to any unfinished line from last time. */
 	if (G.add_cmd_line) {
@@ -496,12 +496,14 @@ static void add_cmd(const char *cmdstr)
 		cmdstr = G.add_cmd_line = tp;
 	}
 
-	/* If this line ends with backslash, request next line. */
-	temp = strlen(cmdstr);
-	if (temp && cmdstr[--temp] == '\\') {
+	/* If this line ends with unescaped backslash, request next line. */
+	n = len = strlen(cmdstr);
+	while (n && cmdstr[n-1] == '\\')
+		n--;
+	if ((len - n) & 1) { /* if odd number of trailing backslashes */
 		if (!G.add_cmd_line)
 			G.add_cmd_line = xstrdup(cmdstr);
-		G.add_cmd_line[temp] = '\0';
+		G.add_cmd_line[len-1] = '\0';
 		return;
 	}
 
@@ -560,7 +562,7 @@ static void add_cmd(const char *cmdstr)
 		/* last part (mandatory) will be a command */
 		if (!*cmdstr)
 			bb_error_msg_and_die("missing command");
-		sed_cmd->cmd = *(cmdstr++);
+		sed_cmd->cmd = *cmdstr++;
 		cmdstr = parse_cmd_args(sed_cmd, cmdstr);
 
 		/* Add the command to the command array */

testsuite/sed.tests

@@ -258,4 +258,18 @@ testing "sed nested {}s" \
 	"qwe\nasd\nacd\nacd\n" "" \
 	"qwe\nasd\nzxc\n"
 
+testing "sed a cmd ended by double backslash" \
+	"sed -e '/| one /a \\
+	| three \\\\' -e '/| one-/a \\
+	| three-* \\\\'" \
+'	| one \\
+	| three \\
+	| two \\
+' '' \
+'	| one \\
+	| two \\
+'
+
+# testing "description" "arguments" "result" "infile" "stdin"
+
 exit $FAILCOUNT

testsuite/testing.sh

@@ -73,7 +73,7 @@ testing()
 
   if [ $# -ne 5 ]
   then
-    echo "Test $NAME has wrong number of arguments (must be 5) ($# $*)" >&2
+    echo "Test $NAME has wrong number of arguments: $# (must be 5)" >&2
     exit 1
   fi