From 63274ac7f99c516b88bd1f94e05e5c715a4800ce Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Tue, 12 Jul 2011 20:41:15 -0400
Subject: [PATCH] Avoid modifying the input command string.

This gives the individual command functions access to the entire
(unadultered) input from the user.
---
 src/cdecl99.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/cdecl99.c b/src/cdecl99.c
index 5c67ed8..2df7ec8 100644
--- a/src/cdecl99.c
+++ b/src/cdecl99.c
@@ -92,7 +92,7 @@ retry:
 	return buf;
 }
 
-static int cmd_explain(char *cmd, char *arg)
+static int cmd_explain(const char *cmd, const char *arg)
 {
 	struct cdecl *decl;
 	const char *str;
@@ -116,7 +116,7 @@ out:
 	return ret;
 }
 
-static int cmd_simplify(char *cmd, char *arg)
+static int cmd_simplify(const char *cmd, const char *arg)
 {
 	struct cdecl *decl;
 	const char *str;
@@ -151,16 +151,16 @@ out:
 	return ret;
 }
 
-static int cmd_quit(char *cmd, char *arg)
+static int cmd_quit(const char *cmd, const char *arg)
 {
 	return 0;
 }
 
-static int cmd_help(char *cmd, char *arg);
+static int cmd_help(const char *cmd, const char *arg);
 
 static const struct command {
 	char name[16];
-	int (*func)(char *cmd, char *arg);
+	int (*func)(const char *cmd, const char *arg);
 	const char *blurb;
 } commands[] = {
 	{ "explain",  cmd_explain,  "Explain a C declaration." },
@@ -171,7 +171,7 @@ static const struct command {
 };
 static const size_t ncommands = sizeof commands / sizeof commands[0];
 
-static int cmd_help(char *cmd, char *arg)
+static int cmd_help(const char *cmd, const char *arg)
 {
 	for (size_t i = 0; i < ncommands; i++) {
 		if (!commands[i].blurb)
@@ -183,24 +183,37 @@ static int cmd_help(char *cmd, char *arg)
 	return 1;
 }
 
-static int run_command(char *line)
+/*
+ * Ensure that the first n characters of str equal the entire (null-terminated)
+ * string cmd.
+ */
+static int cmd_cmp(const char *str, const char *cmd, size_t n)
+{
+	size_t cmdlen = strlen(cmd);
+
+	if (n < cmdlen)
+		return -1;
+	if (n > cmdlen)
+		return 1;
+	return memcmp(str, cmd, n);
+}
+
+static int run_command(const char *line)
 {
-	char *cmd = line + strspn(line, " \t");
-	char *arg = cmd  + strcspn(cmd, " \t");
+	const char *cmd = line + strspn(line, " \t");
+	const char *arg = cmd  + strcspn(cmd, " \t");
 
 	if (cmd[0] == '\0')
 		return 1;
-	if (arg[0] != '\0')
-		*arg++ = '\0';
 
 	for (size_t i = 0; i < ncommands; i++) {
-		if (strcmp(cmd, commands[i].name) != 0)
+		if (cmd_cmp(cmd, commands[i].name, arg-cmd) != 0)
 			continue;
 
 		return commands[i].func(cmd, arg);
 	}
 
-	fprintf(stderr, "Undefined command: %s\n", cmd);
+	fprintf(stderr, "Undefined command: %.*s\n", (int)(arg-cmd), cmd);
 	return -1;
 }
 
-- 
2.43.2