pipes

README.md

@@ -26,11 +26,10 @@ $ ./rush
 - Showing current time and directory with custom color
 - Syntax highlighting on valid commands using ANSI colors
 - History navigation using up and down keys with history command
-- Built in commands
-- Export environment variable
-- Source commands from a file
+- Support for environment variables
 - Editing using left and right arrow keys
 - !! to repeat last command
+- Pipes
 
 # Built in commands
 - cd
@@ -41,7 +40,6 @@ $ ./rush
 - source
 
 # Todo Features
-- splits commands based on pipes and whitespaces
 - stdin, stdout, stderr redirect
 - background jobs
 - tab completion

commands.c

@@ -159,8 +159,6 @@ int execute(char **args) {
         return 1;
     }
     
-    save_command_history(args); // save command to history file
-
     // prioritize builtin commands
     for (int i = 0; i < num_builtins(); i++) {
         if (strcmp(args[0], builtin_cmds[i]) == 0) {
@@ -199,3 +197,51 @@ int execute(char **args) {
 
     return 1;
 }
+
+// execute_pipe with as many pipes as needed
+int execute_pipe(char ***args) {
+    int pipefd[2];
+    int status;
+    pid_t pid;
+    int i = 0;
+    int in = 0;
+
+    int num_pipes = 0;
+    while (args[num_pipes] != NULL) {
+        num_pipes++;
+    }
+
+    for (i = 0; i < num_pipes; i++) {
+        pipe(pipefd);
+        if ((pid = fork()) == 0) {
+            dup2(in, 0); // change input according to the old one
+            if (i < num_pipes - 1) {
+                dup2(pipefd[1], 1); // change output according to the new one
+            }
+            close(pipefd[0]);
+            execvp(args[i][0], args[i]);
+            exit(EXIT_FAILURE);
+        } else if (pid < 0) {
+            perror("fork failed");
+        }
+        close(pipefd[1]);
+        in = pipefd[0];
+    }
+
+    if ((pid = fork()) == 0) {
+        dup2(in, 0);
+        execvp(args[i][0], args[i]);
+        exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        perror("fork failed");
+    }
+
+    close(pipefd[0]);
+    close(pipefd[1]);
+
+    for (i = 0; i <= num_pipes; i++) {
+        wait(&status);
+    }
+
+    return 1;
+}

commands.h

@@ -4,5 +4,6 @@
 int num_builtins();
 bool is_builtin(char *command);
 int execute(char **args);
+int execute_pipe(char ***args);
 
 #endif

history.c

@@ -47,7 +47,7 @@ void check_history_file() {
     }
 }
 
-void save_command_history(char **args) {
+void save_command_history(char *args) {
     history_file = fopen(histfile_path, "a+");
     if (history_file == NULL) {
         fprintf(stderr, "rush: Error opening history file\n");
@@ -55,10 +55,7 @@ void save_command_history(char **args) {
     }
     char cmd[RL_BUFSIZE];
     cmd[0] = '\0';
-    for (int i = 0; args[i] != NULL; ++i) {
-        strcat(cmd, args[i]);
-        strcat(cmd, " ");
-    }
+    strcat(cmd, args);
     int cmd_len = strlen(cmd);
     cmd[cmd_len] = '\n'; // put new line feed to split commands
     // ptr to first obj, size of each obj, number of obj, file ptr

history.h

@@ -1,7 +1,7 @@
 #ifndef HISTORY_H_
 #define HISTORY_H_
 
-void save_command_history(char **args);
+void save_command_history(char *args);
 void check_history_file();
 char *read_command(int direction);
 char **get_all_history(bool check);

rush.c

@@ -7,6 +7,7 @@
 #include <time.h>
 #include <stdbool.h>
 #include <signal.h>
+#include <ctype.h>
 
 #include "color.h"
 #include "constants.h"
@@ -386,8 +387,11 @@ char **argsplit(char *line) {
 char **modifyargs(char **args) {
     int num_arg = 0;
 
+    while (args[num_arg] != NULL) {
+        num_arg++;
+    }
     // makes ls and diff have color without user typing it
-    if (strncmp(args[0], "ls", 2) == 0 || strncmp(args[0], "diff", 4) == 0) {
+    if (strncmp(args[0], "ls", 2) == 0 || strncmp(args[0], "diff", 4) == 0 || strncmp(args[0], "grep", 4) == 0) {
         args[num_arg] = "--color=auto";
         num_arg++;
         args[num_arg] = NULL;
@@ -396,6 +400,49 @@ char **modifyargs(char **args) {
     return args;
 }
 
+char *trimws(char *str) {
+	char *end;
+	while (isspace((unsigned char) *str))
+        str++;
+	if(*str == 0)
+		return str;
+	end = str + strlen(str) - 1;
+	while (end > str && isspace((unsigned char) *end))
+        end--;
+	*(end+1) = 0;
+	return str;
+}
+
+char ***pipe_argsplit(char *line) {
+    char ***cmdv = malloc(sizeof(char **) * 128); // 127 commands, 1 for NULL
+    if (cmdv == NULL) {
+        fprintf(stderr, "rush: Error allocating memory\n");
+        exit(EXIT_FAILURE);
+    }
+    char **cmds = malloc(sizeof(char *) * 128); // 127 arguments, 1 for NULL
+    if (cmds == NULL) {
+        fprintf(stderr, "rush: Error allocating memory\n");
+        exit(EXIT_FAILURE);
+    }
+    int num_arg = 0;
+    char *pipe = strtok(line, "|");
+    while (pipe != NULL) {
+        pipe = trimws(pipe);
+        cmds[num_arg] = strdup(pipe);
+        pipe = strtok(NULL, "|");
+        num_arg++;
+    }
+    cmds[num_arg] = NULL;
+
+    for (int i = 0; i < num_arg; i++) {
+        char **splitted = argsplit(cmds[i]);
+        cmdv[i] = modifyargs(splitted);
+    }
+    cmdv[num_arg] = NULL;
+    free(cmds);
+    return cmdv;
+}
+
 // continously prompt for command and execute it
 void command_loop(char **paths) {
     char *line;
@@ -425,12 +472,28 @@ void command_loop(char **paths) {
 
 
         line = readline(paths);
-        args = argsplit(line);
-        args = modifyargs(args);
-        status = execute(args);
-
+        save_command_history(line);
+        bool has_pipe = false;
+        for (int i = 0; line[i] != '\0'; i++) {
+            if (line[i] == '|') {
+                has_pipe = true;
+                break;
+            }
+        }
+        if (has_pipe) {
+            char ***pipe_args = pipe_argsplit(line);
+            status = execute_pipe(pipe_args);
+            while (*pipe_args != NULL) {
+                free(*pipe_args);
+                pipe_args++;
+            }
+        } else {
+            args = argsplit(line);
+            args = modifyargs(args);
+            status = execute(args);
+            free(args);
+        }
         free(line);
-        free(args);
         free(cwd);
     };
 }