From 903f33f40bc668843c8e8aaf6b61b28366e9e8c3 Mon Sep 17 00:00:00 2001
From: Nicolas Berr <nicolas@igor.lfbs.rwth-aachen.de>
Date: Fri, 23 Sep 2011 15:31:44 +0200
Subject: [PATCH] - added support for changing current working directory -
 added cd, pwd command

---
 newlib/examples/mshell.c | 83 ++++++++++++++++++++++++++++++++++------
 1 file changed, 72 insertions(+), 11 deletions(-)

diff --git a/newlib/examples/mshell.c b/newlib/examples/mshell.c
index 74323f3b..1f43a821 100644
--- a/newlib/examples/mshell.c
+++ b/newlib/examples/mshell.c
@@ -24,7 +24,9 @@
 #include <ctype.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/stat.h>
 #undef errno
+
 extern int errno;
 
 void showlogo() {
@@ -35,14 +37,22 @@ void showlogo() {
 }
 
 void help() {
-	printf("possible commands: \n");
-	printf("exit > exit shell \n");
+	printf("shell builtin commands: \n");
+	printf("cd <path>:\t change current working directory to path\n");
+	printf("pwd      :\t show current working directory\n");
+	printf("help     :\t this short help\n");
+	printf("exit     :\t exit the shell \n");
 }
 
-#define MAXARGS 16
+#define MAXARGS    16
+#define MAXPATH    128
+#define MAXCMDLINE 1024
 
 #define ST_WHITE 0
-#define ST_ARG 1
+#define ST_ARG   1
+#define ST_QUOTE 2
+
+#define USE_STAT 0
 
 char** splitargs(char* args) {
 	static char* ret[MAXARGS+1];
@@ -51,14 +61,22 @@ char** splitargs(char* args) {
 	while (*args != '\0') {
 		if (state == ST_WHITE) {
 			if (!isspace(*args)) {
+				if(*args == '"') {
+					args++;
+					state = ST_QUOTE;
+					if (*args == '\0')
+						break;
+				}
+				else {
+					state = ST_ARG;
+				}
 				ret[i++] = args;
 				if (i == MAXARGS)
 					break;
-				state = ST_ARG;
 			}
 		}
 		else {
-			if (isspace(*args)) {
+			if ((state == ST_QUOTE && *args == '"') || isspace(*args)) {
 				*args = '\0';
 				state = ST_WHITE;
 			}
@@ -70,18 +88,57 @@ char** splitargs(char* args) {
 	return ret;
 }
 
+char* ms_getcwd() {
+	return getenv("PWD");
+}
+
+void ms_setcwd(char* path) {
+	static char newpath[MAXPATH];
+	static struct stat stats;
+
+	if (path == NULL)
+		return;
+	
+	if (*path == NULL)
+		return;
+	
+	if (*path == '/') {
+		strcpy(newpath, path);
+	}
+	else {
+		char* oldpath = ms_getcwd();
+
+		if(oldpath[strlen(oldpath)-1] == '/')
+			sprintf(newpath,"%s%s", oldpath, path);
+		else
+			sprintf(newpath,"%s/%s", oldpath, path);
+	}
+
+#if USE_STAT
+	if (stat(newpath, &stats)) {
+		printf("mshell: %s is not a valid path\n", newpath);
+		return;
+	}
+	if (!S_ISDIR(stats.st_mode)) {
+		printf("mshell: %s is not a directory\n", newpath);
+		return;
+	}
+#endif
+
+	setenv("PWD", newpath, 1);
+}
+
 int main(int argc, char** argv)
 {
-	char  commandline[1024];
+	char  commandline[MAXCMDLINE];
 	char* command;
 
-	int size = 0, status = 0;
+	int status = 0;
 	pid_t pid;
 	system("clear");
 	showlogo();
 	while(1) {
 		char** newargv;
-		char*  newenv[] = {"USER=root", "PATH=/bin:/sbin:/usr/bin", "PWD=/", "TEMP=/tmp", NULL};
 		
 		printf("mshell> ");
 		gets(commandline);
@@ -97,12 +154,16 @@ int main(int argc, char** argv)
 		}
 		if(!strcmp(command, "help")) {
 			help();
+		} else if (!strcmp(command, "pwd")) {
+			printf("%s\n", ms_getcwd());
+		} else if (!strcmp(command, "cd")) {
+			ms_setcwd(newargv[1]);
 		} else {
-			char path[128];
+			char path[MAXPATH];
 			sprintf(path, "/bin/%s", command);
 			pid = fork();
 			if (pid == 0) { //child
-				status = execve(path, newargv, newenv);
+				status = execve(path, newargv, environ);
 				if (status)
 					printf("mshell: %s: command not found\n", path);
 				return errno;