[PATCH] subshell_name_quote() use printf instead of echo

[Pavel Tsekov <ptsekov gmx net>]

Hello,

This is patch which makes subshell_name_quote() use the printf
utility instead of echo. Please, test it and let me know whether
to commit it.

P.S. This is not related to the patch - subshell_name_quote() 
includes code to deal with leading '-' character. I think
that this code could eventually lead to memory being overwritten
in certain cases because no space is reserved for those two
characters. What do you think about the following solution -
instead of checking whether we have '-' in the directory
name and prepending ./ we could always prepend "--" - is
this portable ?

Thanks!

Index: src/subshell.c
===================================================================
RCS file: /sources/mc/mc/src/subshell.c,v
retrieving revision 1.94
diff -u -p -r1.94 subshell.c
--- src/subshell.c	1 Mar 2007 11:07:04 -0000	1.94
+++ src/subshell.c	1 Mar 2007 15:43:55 -0000
@@ -687,30 +687,25 @@ exit_subshell (void)
  * executing any commands in the shell.  Escape all control characters.
  * Use following technique:
  *
- * for bash - echo with `-e', 3-digit octal numbers:
- *   cd "`echo -e '\ooo...\ooo'`"
+ * printf(1) with format string containing a single conversion specifier, b,
+ * and an argument which contains a copy of the string passed to 
+ * subshell_name_quote() with all characters, except digits and letters,
+ * replaced by the backslash-escape sequence \0nnn, where "nnn" is the
+ * numeric value of the character converted to octal number.
+ * 
+ *   cd "`printf "%b" 'ABC\0nnnDEF\0nnnXYZ'`"
  *
- * for zsh - echo with `-e', 4-digit octal numbers:
- *   cd "`echo '\oooo...\oooo'`"
- *
- * for tcsh - echo without `-e', 4-digit octal numbers:
- *   cd "`echo '\oooo...\oooo'`"
  */
 static char *
 subshell_name_quote (const char *s)
 {
     char *ret, *d;
-    const char echo_cmd[] = "\"`echo '";
-    const char echo_e_cmd[] = "\"`echo -e '";
-    const char common_end[] = "'`\"";
-    const char *cmd_start;
-    int len;
+    const char quote_cmd_start[] = "\"`printf \"%b\" '";
+    const char quote_cmd_end[] = "'`\"";
 
-    /*
-     * Factor 5 because we need \, 0 and 3 other digits per character
-     * in the worst case (tcsh and zsh).
-     */
-    d = ret = g_malloc (5 * strlen (s) + 16);
+    /* Factor 5 because we need \, 0 and 3 other digits per character. */
+    d = ret = g_malloc (1 + (5 * strlen (s)) + (sizeof(quote_cmd_start) - 1)
+				+ (sizeof(quote_cmd_end) - 1));
     if (!d)
 	return NULL;
 
@@ -720,46 +715,25 @@ subshell_name_quote (const char *s)
 	*d++ = '/';
     }
 
-    /* echo in tcsh doesn't understand the "-e" option */
-    if (subshell_type == TCSH)
-	cmd_start = echo_cmd;
-    else
-	cmd_start = echo_e_cmd;
-
     /* Copy the beginning of the command to the buffer */
-    len = strlen (cmd_start);
-    memcpy (d, cmd_start, len);
-    d += len;
+    strcpy (d, quote_cmd_start);
+    d += sizeof(quote_cmd_start) - 1;
 
     /*
-     * Print every character in octal format with the leading backslash.
-     * bash >= 3.2, tcsh and zsh require 4-digit octals, 2.05b <= bash < 3.2
-     * support 3-digit octals as well as 4-digit octals.
-     * For bash < 2.05b fix below to use 3-digit octals.
+     * Print every character except digits and letters as a backslash-escape
+     * sequence of the form \0nnn, where "nnn" is the numeric value of the
+     * character converted to octal number.
      */
-    if (subshell_type == BASH) {
-	for (; *s; s++) {
-	    /* Must quote numbers, so that they are not glued to octals
-	       for bash < 3.2 */
-	    if (isalpha ((unsigned char) *s)) {
-		*d++ = (unsigned char) *s;
-	    } else {
-		sprintf (d, "\\0%03o", (unsigned char) *s);
-		d += 5;
-	    }
-	}
-    } else {
-	for (; *s; s++) {
-	    if (isalnum ((unsigned char) *s)) {
-		*d++ = (unsigned char) *s;
-	    } else {
-		sprintf (d, "\\0%03o", (unsigned char) *s);
-		d += 5;
-	    }
+    for (; *s; s++) {
+	if (isalnum ((unsigned char) *s)) {
+	    *d++ = (unsigned char) *s;
+	} else {
+	    sprintf (d, "\\0%03o", (unsigned char) *s);
+	    d += 5;
 	}
     }
 
-    memcpy (d, common_end, sizeof (common_end));
+    strcpy (d, quote_cmd_end);
 
     return ret;
 }