add set variable builtin

src/builtins.c

@@ -13,6 +13,7 @@
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
@@ -34,6 +35,10 @@ bool is_builtin(char *command) {
         return true;
     }
 
+    if (strcmp(command, "set") == 0) {
+        return true;
+    }
+
     return false;
 }
 
@@ -47,6 +52,9 @@ void run_builtin(StringArray *args) {
     else if (strcmp(args->array[0], "environ") == 0) {
         print_environ(args);
     }
+    else if (strcmp(args->array[0], "set") == 0) {
+        set_variable(args);
+    }
     else {
         fprintf(stderr, "Builtin %s does not exist!\n", args->array[0]);
     }
@@ -72,10 +80,15 @@ void change_directory(StringArray *args) {
     }
     else {
         if (chdir(args->array[1]) != 0) {
-            perror("cd");
+            fprintf(stderr, "cd: %s \"%s\"\n", strerror(errno), args->array[1]);
         }
         else {
-            set_array_list(variables, "PWD", get_working_directory());
+            char *cwd = get_working_directory();
+            set_array_list(variables, "PWD", cwd);
+            if (cwd != NULL) {
+                free(cwd);
+                cwd = NULL;
+            }
         }
     }
 }
@@ -89,3 +102,81 @@ void print_environ(StringArray *args) {
         fprintf(stdout, "%s=%s\n", variables->keys->array[i], variables->values->array[i]);
     }
 }
+
+void set_variable(StringArray *args) {
+    if (args->size < 4) {
+        fprintf(stderr, "Too few arguments!\n");
+        return;
+    }
+
+    if (strcmp(args->array[2], "=") != 0) {
+        fprintf(stderr, "Invalid arguments!\n");
+        return;
+    }
+
+    if (args->array[1][0] != '$') {
+        fprintf(stderr, "Invalid variable argument!\n");
+        return;
+    }
+
+    char *variable = malloc((strlen(args->array[1])) * sizeof(char *));
+    if (variable == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+    memset(variable, 0, strlen(args->array[1]));
+
+    // Remove the $ symbol from the string
+    for (size_t i = 0; i < strlen(args->array[1]); i++) {
+        variable[i] = args->array[1][i + 1];
+    }
+
+    // Check variable name for invalid characters
+    for (size_t i = 0; i < strlen(variable); i++) {
+        if (!((variable[i] >= 48 && variable[i] <= 57) || 
+                (variable[i] >= 65 && variable[i] <= 90) ||
+                (variable[i] >= 97 && variable[i] <= 122))) {
+            fprintf(stderr, "Invalid character \"%d\" in variable name!\n", variable[i]);
+            return;
+        }
+    }
+
+    size_t value_length = 1;
+    for (size_t i = 3; i < args->size; i++) {
+        if (i != 3) {
+            value_length++;
+        }
+        value_length += strlen(args->array[i]);
+    }
+
+    char *value = malloc(value_length * sizeof(char *));
+    if (value == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+    memset(value, 0, value_length);
+
+    for (size_t i = 3; i < args->size; i++) {
+        if (i != 3) {
+            strcat(value, " ");
+        }
+        strcat(value, args->array[i]);
+    }
+
+    if (strcmp(variable, "PWD") == 0) {
+        StringArray *chdir_args = create_string_array();
+        insert_string_array(chdir_args, "cd");
+        insert_string_array(chdir_args, args->array[3]);
+        change_directory(chdir_args);
+        free_string_array(chdir_args);
+        free(variable);
+        free(value);
+        // return without setting the variable because change directory will set it on success.
+        return;
+    }
+
+    set_array_list(variables, variable, value);
+
+    free(variable);
+    free(value);
+}

src/include/builtins.h

@@ -48,6 +48,12 @@ void change_directory(StringArray *args);
  * Print all of the environment variables.
  * @param args The arguments the user input.
  */
-void print_environ(StringArray * args);
+void print_environ(StringArray *args);
+
+/**
+ * Set an environment variable.
+ * @param args The arguments passed to set.
+ */
+void set_variable(StringArray *args);
 
 #endif