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w5/codes/dshlib.c

+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "dshlib.h"
+
+/*
+ *  build_cmd_list
+ *    cmd_line:     the command line from the user
+ *    clist *:      pointer to clist structure to be populated
+ *
+ *  This function builds the command_list_t structure passed by the caller
+ *  It does this by first splitting the cmd_line into commands by spltting
+ *  the string based on any pipe characters '|'.  It then traverses each
+ *  command.  For each command (a substring of cmd_line), it then parses
+ *  that command by taking the first token as the executable name, and
+ *  then the remaining tokens as the arguments.
+ *
+ *  NOTE your implementation should be able to handle properly removing
+ *  leading and trailing spaces!
+ *
+ *  errors returned:
+ *
+ *    OK:                      No Error
+ *    ERR_TOO_MANY_COMMANDS:   There is a limit of CMD_MAX (see dshlib.h)
+ *                             commands.
+ *    ERR_CMD_OR_ARGS_TOO_BIG: One of the commands provided by the user
+ *                             was larger than allowed, either the
+ *                             executable name, or the arg string.
+ *
+ *  Standard Library Functions You Might Want To Consider Using
+ *      memset(), strcmp(), strcpy(), strtok(), strlen(), strchr()
+ */
+
+/*
+ * Helper function to trim leading and trailing spaces
+ */
+void trim_whitespace(char *str) {
+    char *end;
+
+    // Trim leading space
+    while (isspace((unsigned char)*str)) str++;
+
+    if (*str == 0) return; // Empty string
+
+    // Trim trailing space
+    end = str + strlen(str) - 1;
+    while (end > str && isspace((unsigned char)*end)) end--;
+
+    // Write new null terminator
+    *(end + 1) = '\0';
+}
+
+/*
+ *  build_cmd_list
+ *    cmd_line:     the command line from the user
+ *    clist *:      pointer to clist structure to be populated
+ */
+int build_cmd_list(char *cmd_line, command_list_t *clist)
+{
+    
+    if (cmd_line == NULL || strlen(cmd_line) == 0) {
+        return WARN_NO_CMDS;
+    }
+
+    // Initialize command list
+    memset(clist, 0, sizeof(command_list_t));
+
+    char *token;
+    char *rest = cmd_line;
+    int cmd_count = 0;
+
+    // Split input line by pipes (`|`)
+    while ((token = strtok_r(rest, PIPE_STRING, &rest))) {
+        if (cmd_count >= CMD_MAX) {
+            return ERR_TOO_MANY_COMMANDS;  // return the error
+        }
+
+        // Trim leading and trailing spaces
+        trim_whitespace(token);
+
+        // Check if command is too large
+        if (strlen(token) >= SH_CMD_MAX) {
+            return ERR_CMD_OR_ARGS_TOO_BIG; // return the error
+        }
+
+        // Split command into executable and arguments
+        char *cmd_part = strtok(token, " ");
+        if (cmd_part == NULL) {
+            continue;  // Skip empty commands
+        }
+
+        // Store the executable name
+        strncpy(clist->commands[cmd_count].exe, cmd_part, EXE_MAX - 1);
+        clist->commands[cmd_count].exe[EXE_MAX - 1] = '\0';
+
+        // Store the arguments
+        char *arg_buffer = clist->commands[cmd_count].args;
+        arg_buffer[0] = '\0';
+
+        cmd_part = strtok(NULL, " ");
+        while (cmd_part) {
+            strncat(arg_buffer, cmd_part, ARG_MAX - strlen(arg_buffer) - 1);
+            strncat(arg_buffer, " ", ARG_MAX - strlen(arg_buffer) - 1);
+            cmd_part = strtok(NULL, " ");
+        }
+
+        // Remove trailing space from arguments
+        trim_whitespace(arg_buffer);
+
+        cmd_count++;
+    }
+
+    clist->num = cmd_count;
+    return OK;
+
+    
+    //printf(M_NOT_IMPL);
+    //return EXIT_NOT_IMPL;
+}