[cmdline] Add generic concat_args() function

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/exec.c

 	return rc;
 }
 
+/**
+ * Concatenate arguments
+ *
+ * @v args		Argument list (NULL-terminated)
+ * @ret string		Concatenated arguments
+ *
+ * The returned string is allocated with malloc().  The caller is
+ * responsible for eventually free()ing this string.
+ */
+char * concat_args ( char **args ) {
+	char **arg;
+	size_t len;
+	char *string;
+	char *ptr;
+
+	/* Calculate total string length */
+	len = 1 /* NUL */;
+	for ( arg = args ; *arg ; arg++ )
+		len += ( 1 /* possible space */ + strlen ( *arg ) );
+
+	/* Allocate string */
+	string = zalloc ( len );
+	if ( ! string )
+		return NULL;
+
+	/* Populate string */
+	ptr = string;
+	for ( arg = args ; *arg ; arg++ ) {
+		ptr += sprintf ( ptr, "%s%s",
+				 ( ( ptr == string ) ? "" : " " ), *arg );
+	}
+	assert ( ptr < ( string + len ) );
+
+	return string;
+}
+
 /**
  * "echo" command
  *
  * @v argv		Argument list
  * @ret rc		Return status code
  */
-static int echo_exec ( int argc, char **argv ) {
-	int i;
+static int echo_exec ( int argc __unused, char **argv ) {
+	char *text;
 
-	for ( i = 1 ; i < argc ; i++ ) {
-		printf ( "%s%s", ( ( i == 1 ) ? "" : " " ), argv[i] );
-	}
-	printf ( "\n" );
+	text = concat_args ( &argv[1] );
+	if ( ! text )
+		return -ENOMEM;
+	printf ( "%s\n", text );
+	free ( text );
 	return 0;
 }
 

src/hci/commands/image_cmd.c

  * Fill in image command line
  *
  * @v image		Image
- * @v nargs		Argument count
  * @v args		Argument list
  * @ret rc		Return status code
  */
-static int imgfill_cmdline ( struct image *image, unsigned int nargs, 
-			     char **args ) {
-	size_t len = 0;
-	unsigned int i;
-
-	/* Clear command line if no arguments given */
-	if ( ! nargs )
-		return image_set_cmdline ( image, NULL );
-
-	/* Determine total length of command line */
-	for ( i = 0 ; i < nargs ; i++ )
-		len += ( strlen ( args[i] ) + 1 /* space or NUL */ );
-
-	{
-		char buf[len];
-		char *ptr = buf;
-
-		/* Assemble command line */
-		buf[0] = '\0';
-		for ( i = 0 ; i < nargs ; i++ ) {
-			ptr += sprintf ( ptr, "%s%s", ( i ? " " : "" ),
-					 args[i] );
-		}
-		assert ( ptr < ( buf + len ) );
+static int imgfill_cmdline ( struct image *image, char **args ) {
+	char *cmdline = NULL;
+	int rc;
 
-		return image_set_cmdline ( image, buf );
+	/* Construct command line (if arguments are present) */
+	if ( *args ) {
+		cmdline = concat_args ( args );
+		if ( ! cmdline )
+			return -ENOMEM;
 	}
+
+	/* Apply command line */
+	rc = image_set_cmdline ( image, cmdline );
+	free ( cmdline );
+	return rc;
 }
 
 /** "imgfetch" options */
 		return rc;
 
 	/* Fill in command line */
-	if ( ( rc = imgfill_cmdline ( image, ( argc - optind - 1 ),
-				      &argv[ optind + 1 ] ) ) != 0 )
+	if ( ( rc = imgfill_cmdline ( image, &argv[ optind + 1 ] ) ) != 0 )
 		return rc;
 
 	/* Fetch the image */
 		return rc;
 
 	/* Fill in command line */
-	if ( ( rc = imgfill_cmdline ( image, ( argc - optind - 1 ),
-				      &argv[ optind + 1 ] ) ) != 0 )
+	if ( ( rc = imgfill_cmdline ( image, &argv[ optind + 1 ] ) ) != 0 )
 		return rc;
 
 	return 0;

src/include/ipxe/command.h

 
 #define __command __table_entry ( COMMANDS, 01 )
 
+extern char * concat_args ( char **args );
+
 #endif /* _IPXE_COMMAND_H */