Add support for PATH and other environment variables

Also, the shell prompt now has color

Makefile

@@ -1,6 +1,6 @@
 CC=gcc
-CFLAGS=-Wall -Werror -std=c99
-OBJS= err_handling.o trie/trie.o trie/intern.o builtin.o argbuild.o vsh.o
+CFLAGS=-pedantic -Wall -Wextra -Werror -std=c99
+OBJS=err_handling.o trie/trie.o trie/intern.o builtin.o argbuild.o vsh.o envmgr.o
 BINARY=vsh
 
 .PHONY: clean all debug release

builtin.c

@@ -5,6 +5,7 @@
 #include <unistd.h>
 #include <string.h>
 
+#include "envmgr.h"
 #include "vsh.h"
 #include "trie/trie.h"
 
@@ -17,7 +18,7 @@ typedef struct func_ary_elt{
   char* cmd_name;
 } func_ary_elt_t;
 
-int shell_exit(int argc, char** argv){
+int shell_exit(__attribute__((unused))int argc, __attribute__((unused))char** argv){
   running = 0;
   return 0;
 }
@@ -33,6 +34,8 @@ int change_directory(int argc, char** argv){
   last_cmd_errno = errno;
   if(toreturn){
     errstr = strerror(last_cmd_errno);
+  }else{
+      update_pwd();
   }
   return toreturn;
 }

envmgr.c

@@ -0,0 +1,78 @@
+#include "envmgr.h"
+
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <linux/limits.h>
+
+static char* pwd;
+static char* old_pwd;
+
+static char prog_path[PATH_MAX];
+
+//The compiler throws a hissyfit if setenv doesn't have a function declaration
+//here, despite the fact that it *IS* in stdlib.h which *IS* #include'd
+int setenv(const char*, const char*, int);
+
+void init_envmgr(){
+    pwd = malloc(sizeof(char) * PATH_MAX);
+    if(getcwd(pwd, PATH_MAX) != pwd){
+	pwd[0] = '\0';
+    }
+    old_pwd = malloc(sizeof(char) * PATH_MAX);
+}
+
+void deinit_envmgr(){
+    free(pwd);
+    free(old_pwd);
+}
+
+const char* get_pwd(){
+    return pwd;
+}
+
+void update_pwd(){
+    strncpy(old_pwd, pwd, PATH_MAX);
+    if(getcwd(pwd, PATH_MAX) != pwd){
+	pwd[0] = '\0';
+    }
+    setenv("PWD", pwd, 1);
+    setenv("OLDPWD", old_pwd, 1);
+}
+
+void execute_program(char* program, char** arguments){
+    //Try to execute the program in all the paths found in $PATH
+    //But first, try to execute it in the current directory
+    execv(program, arguments);
+    //If we return from an execv call, it failed
+    char* pathstr = getenv("PATH");
+
+    if(!pathstr)
+	return;
+
+    char* begincolon = pathstr;
+    char* endcolon = NULL;
+    do{
+	if(*pathstr == ':' || *pathstr == '\0'){
+	    endcolon = pathstr;
+	    int size = endcolon - begincolon;
+	    strncpy(prog_path, begincolon, size);
+	    //Add a slash to the end of the path before concatenating
+	    //our command string
+	    prog_path[size] = '/';
+
+	    //Now add our command to the end
+	    char* cat_begin = (prog_path + size + 1);
+	    //don't let anyone copy past the end of the array
+	    size = PATH_MAX - size - 1;
+	    strncpy(cat_begin, program, size);
+
+	    //Now try to run the program from that location
+	    execv(prog_path, arguments);
+	    begincolon = endcolon + 1;
+
+	}
+    }while(*(pathstr++) != '\0');
+
+    //If we get to here, then the command could not be found
+}

envmgr.h

@@ -0,0 +1,14 @@
+#ifndef ENVIRONMENT_MANAGER_H
+#define ENVIRONMENT_MANAGER_H
+
+#include <stdlib.h>
+
+void init_envmgr();
+void deinit_envmgr();
+
+void update_pwd();
+const char* get_pwd();
+void execute_program(char* program, char** arguments);
+
+
+#endif

vsh.c

@@ -6,81 +6,84 @@
 #include <sys/wait.h>
 #include <assert.h>
 
+#include "envmgr.h"
 #include "argbuild.h"
 #include "builtin.h"
 #include "err_handling.h"
 
-#define DIR_STR_SIZ 1024
+#define RED   "\x1B[31m"
+#define GRN   "\x1B[32m"
+#define YEL   "\x1B[33m"
+#define BLU   "\x1B[34m"
+#define MAG   "\x1B[35m"
+#define CYN   "\x1B[36m"
+#define WHT   "\x1B[37m"
+#define RESET "\x1B[0m"
+
+int main(int __attribute__((unused))argc, char** argv){
+    me = argv[0];
+    running = 1;
+
+    const long ARG_MAX = sysconf(_SC_ARG_MAX);
+    char* cmdbuf = malloc(sizeof(char) * ARG_MAX);
+    //This holds all the args that a child could be passed.
+    //ARG_MAX is the maximum length of an argument, so there
+    //can never be more than ARG_MAX/2 arguments (assuming there
+    //are ARG_MAX arguments of 1 char each separated by spaces)
+    char** child_argv = malloc(sizeof(char) * (ARG_MAX / 2));
+    last_argv = child_argv;
+
+    char user_prompt = '$';
+    if(geteuid() == 0)
+	user_prompt = '#';
+
+    init_builtin_commands();
+    init_envmgr();
+
+    puts("Welcome to vsh, the Vukelich Shell.\n");
+
+    while(running){
+
+	printf(CYN "%s %c " RESET, get_pwd(), user_prompt);
+
+	if(fgets(cmdbuf, ARG_MAX, stdin) != cmdbuf){
+	    puts("");
+	    running = 0;
+	    continue;
+	}
+
+	arg_t* args = build_args(cmdbuf, ARG_MAX);
+
+	//Get our argc and fill our argv
+	int child_argc = get_args(args, child_argv);
+
+	//See if the command we've been given should be
+	//executed internally.  If not, assume it's a
+	//program
+	run_builtin_command(child_argc, child_argv);
+	if(!builtin_cmd_found){
+	    if(!fork()){
+		execute_program(child_argv[0], child_argv);
+		printf("%s: %s: Command not found\n", me, child_argv[0]);
+		return 1;
+	    }
+	    wait(NULL);
+	}
+
+	//If the user ran a command built in to the shell
+	//(like cd), and it had an error, print that error
+	if(builtin_cmd_found && last_cmd_code){
+	    print_error();
+	}
+
+	free_args(args);
 
-int main(int argc, char** argv, char** envp){
-  me = argv[0];
-  running = 1;
-  char pwd[DIR_STR_SIZ];
-  const long ARG_MAX = sysconf(_SC_ARG_MAX);
-  char* cmdbuf = malloc(sizeof(char) * ARG_MAX);
-  //This holds all the args that a child could be passed.
-  //ARG_MAX is the maximum length of an argument, so there
-  //can never be more than ARG_MAX/2 arguments (assuming there
-  //are ARG_MAX arguments of 1 char each separated by spaces)
-  char** child_argv = malloc(sizeof(char) * (ARG_MAX / 2));
-  last_argv = child_argv;
-
-  char user_prompt = '$';
-  if(geteuid() == 0)
-    user_prompt = '#';
-
-  init_builtin_commands();
-
-  puts("Welcome to vsh, the Vukelich Shell.\n");
-
-
-  while(running){
-
-    //Get the current working directory.  If an error occurs, then
-    //set the pwd string to empty
-    if(getcwd(pwd, DIR_STR_SIZ) != pwd){
-      pwd[0] = '\0';
     }
+    puts("Exiting");
+    free(cmdbuf);
+    free(child_argv);
+    deinit_builtin_commands();
+    deinit_envmgr();
 
-    printf("%s %c ", pwd, user_prompt);
-
-    if(fgets(cmdbuf, ARG_MAX, stdin) != cmdbuf){
-      puts("");
-      running = 0;
-      continue;
-    }
-
-    arg_t* args = build_args(cmdbuf, ARG_MAX);
-
-    //Get our argc and fill our argv
-    int child_argc = get_args(args, child_argv);
-
-    //See if the command we've been given should be
-    //executed internally.  If not, assume it's a
-    //program
-    run_builtin_command(child_argc, child_argv);
-    if(!builtin_cmd_found){
-      if(!fork()){
-	execve(child_argv[0], child_argv, envp);
-	printf("%s: %s: Command not found\n", me, child_argv[0]);
-	return 1;
-      }
-      wait(NULL);
-    }
-
-    //If the user ran a command built in to the shell
-    //(like cd), and it had an error, print that error
-    if(builtin_cmd_found && last_cmd_code){
-      print_error();
-    }
-
-    free_args(args);
-
-  }
-  puts("Exiting");
-  free(cmdbuf);
-  free(child_argv);
-  deinit_builtin_commands();
-
-  return 0;
+    return 0;
 }