Fix small behaviors

smallsh/main.c

@@ -5,16 +5,11 @@ int stop_msg = 0;
 
 int main() {
 
-  /*
+  // Signal Handling
-  struct sigaction sa;
-    sa.sa_handler = sigstop_handle;
-    sa.sa_flags = 0;
-    sigemptyset(&sa.sa_mask);
-    */
-
   signal(SIGINT, sigint_handle);
   signal(SIGTSTP, sigstop_handle);
 
+  // Reusable Variables
   int status = 0;
   size_t input_size = 2048;
   size_t getline_len;
@@ -22,9 +17,10 @@ int main() {
 
   while(1) {
 
+    // Check and reap children that have exited
     clean_children();
 
-    //signal handling
+    // Handle Switching Between Stop Mode
     if(stop_msg) {
       if(stop_flag) 
         printf("Entering Stop Mode: Background Processes Do Not Work (&)\n");
@@ -34,11 +30,13 @@ int main() {
     }
 
 
+    // Shell Value Grabbing
     printf(": ");
     fflush(stdout);
     getline_len = getline(&input, &input_size, stdin);
     input[getline_len - 1] = '\0';
 
+    // Fill in PID for '$$'
     expand_dollar(input, input_size);
 
     // Ignore whitespace or comments
@@ -47,8 +45,7 @@ int main() {
       continue;
     }
 
-
+    // Format Line as Array
-
     char*** array = malloc(sizeof(char**));
     int num_strings = input_format(input, input_size, array);
 
@@ -68,6 +65,7 @@ int main() {
   }
 }
 
+// Build the array with each argument out of line
 int input_format(char* input, size_t input_size, char*** array) {
 
   const int max_args = 512;
@@ -99,6 +97,7 @@ void inbuilt_cd(char* args) {
 
 int run_command(char*** array, int num_array) {
 
+  // Point all executables to /usr/bin (bad Idea but it works)
   char* comb_string = malloc(sizeof(char) * 100);
   sprintf(comb_string, "/usr/bin/");
   strcat(comb_string, (*array)[0]);
@@ -131,6 +130,7 @@ int run_command(char*** array, int num_array) {
     }
   }
 
+  // Make array not have nullspace between non-null values
   sterilize_array(array, num_array);
 
   // Check to see if the process has input redirected
@@ -152,17 +152,21 @@ int run_command(char*** array, int num_array) {
     }
   }
 
+  // Make array not have nullspace between non-null values
   sterilize_array(array, num_array);
 
+  // Forking/Child processes
   int f = fork();
   pid_t pid;
   if(!f) {
+    // Handle Redirected output
     if(redirect_o) {
       int fd = open(redirect_o_str, O_WRONLY | O_CREAT, 0666);
       dup2(fd, STDOUT_FILENO);
       dup2(fd, STDERR_FILENO);
 
     }
+    // Or direct to null if in background
     else if(background) {
       int fd = open("/dev/null", O_WRONLY, 0666);
       //Direct to dev null
@@ -170,24 +174,32 @@ int run_command(char*** array, int num_array) {
       dup2(fd, STDERR_FILENO);
     }
 
+    // Handle Redirected input
     if(redirect_i) {
       int fd = open(redirect_i_str, O_RDONLY);
       dup2(fd, STDIN_FILENO);
     }
+
+    // Or direct to null if in background
     else if(background) {
       int fd = open("/dev/null", O_RDONLY);
       dup2(fd, STDIN_FILENO);
     }
 
+    // Spawn new Process
     pid = execv(comb_string, (*array));
 
+    // Handle error on spawning process
     perror(comb_string);
     exit(1);
   }
+
+  // If in background, tell user the pid that was spawned
   else if(background){
     printf("background pid is %d\n", f);
   }
 
+  // Wait on the process if it is running in forground
   int status;
   if(!background)
     waitpid(f, &status, 0);
@@ -195,7 +207,6 @@ int run_command(char*** array, int num_array) {
   free(comb_string);
 
   return status;
-
 }
 
 
@@ -207,14 +218,15 @@ void expand_dollar(char* input, size_t input_size) {
 
   char* dollar;
 
+  // Check for two '$$'s and exchange them to the pid if they exist
   dollar = strstr(input, "$$");
   while(dollar != NULL) {
 
-  dollar[0] = '%';
+    dollar[0] = '%';
-  dollar[1] = 's';
+    dollar[1] = 's';
-  sprintf(buffer, input, pid);
+    sprintf(buffer, input, pid);
-  strcpy(input, buffer);
+    strcpy(input, buffer);
-  dollar = strstr(input, "$$");
+    dollar = strstr(input, "$$");
   }
 }
 
@@ -246,7 +258,8 @@ void sterilize_array(char*** array, size_t num_array) {
 void sigint_handle() {
 }
 
-void sigstop_handle(int n) {
+void sigstop_handle() {
+  // Negate flags so that it handles both starting and stopping
   stop_flag = !stop_flag;
   stop_msg = !stop_msg;
 }
@@ -257,9 +270,14 @@ void clean_children() {
   int pid = 43110;
   while(pid >0) {
     int status;
-    pid = waitpid(0, &status, WNOHANG);
+    pid = waitpid(0, &status, WNOHANG | WUNTRACED );
 
-    if(pid > 0)
+    // Handle terminated with status or signal
-      printf("\nbackground pid %d is done: exit value %d\n", pid, WEXITSTATUS(status));
+    if(pid > 0) {
+      if(WIFSIGNALED(status))
+        printf("\nbackground pid %d is done: terminated with signal %d\n", pid, WTERMSIG(status));
+      else
+        printf("\nbackground pid %d is done: exit value %d\n", pid, WEXITSTATUS(status));
+    }
   }
 }