From ddcf611815c145b1fadca042e65648a7a81cc497 Mon Sep 17 00:00:00 2001
From: "Douglas B. Rumbaugh" <doug@douglasrumbaugh.com>
Date: Sat, 1 Nov 2025 14:53:14 -0400
Subject: Added variable support

---
 src/command.c   | 10 +++++++++-
 src/hush.c      | 38 +++++++++++++++++++++++++++++++++++---
 src/variables.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+), 4 deletions(-)
 create mode 100644 src/variables.c

(limited to 'src')

diff --git a/src/command.c b/src/command.c
index 20b00b1..3d63121 100644
--- a/src/command.c
+++ b/src/command.c
@@ -119,7 +119,15 @@ pid_t execute_command(command *cmd) {
       close(cmd->pipe[1]);
     }
     
-    execvp(cmd->command, cmd->args);
+    /* 
+     * NOTE: discarding the const qualifier here is okay because either
+     * 1) exec fails, in which case the process is aborted immediately
+     * 2) exec succeeds, in which case the memory is released immediately
+     *
+     * In either case, the args won't be accessed again.
+     */
+    execvp(cmd->command, (char**)cmd->args);
+
     perror("Could not run command");
     exit(EXIT_FAILURE);
   }  else if (res < 0) {
diff --git a/src/hush.c b/src/hush.c
index 557ae1e..0d25244 100644
--- a/src/hush.c
+++ b/src/hush.c
@@ -14,6 +14,7 @@
 #include "config.h"
 #include "lexer.h"
 #include "command.h"
+#include "variables.h"
 
 FILE *open_input(int argc, char **argv) {
   FILE *input_file = (argc > 1) ? fopen(argv[1], "r") : stdin;
@@ -34,10 +35,38 @@ static size_t get_command_len(char *cmdstr) {
   return len;
 }
 
+void variable_substitution(command *cmds) {
+  for (command *cmd = cmds; cmd; cmd = cmd->next) {
+    fprintf(stderr, "Before substitution\n");
+    print_commands(stderr, cmd);
+    for (size_t i=0; i < MAX_ARGUMENT_CNT + 1; i++) {
+      if (is_variable(cmd->args[i])) { 
+        cmd->args[i] = get_variable(cmd->args[i]);
+      }
+    }
+
+    if (is_variable(cmd->outfile)) {
+      cmd->outfile = get_variable(cmd->outfile);
+    }
+
+    if (is_variable(cmd->infile)) {
+      cmd->infile = get_variable(cmd->infile);
+    }
+
+    fprintf(stderr, "After substitution\n");
+    print_commands(stderr, cmd);
+  }
+}
+
 int main(int argc, char **argv) {
   FILE *input_file = open_input(argc, argv);
   char buffer[MAX_LINE_LEN];
 
+  if (!init_variable_store()) {
+    fprintf(stderr, "ERROR: Failed to initialize variable store\n");
+    exit(EXIT_FAILURE);
+  }
+
   fprintf(stdout, "$ ");
   while (fgets(buffer, MAX_LINE_LEN, input_file)) {
     char *cmdstr = trim(buffer);
@@ -68,7 +97,9 @@ int main(int argc, char **argv) {
     // print_parsed_command(stdout, parsed_cmd);
 
     if (parsed_cmd->type == TKN_VARKEY) {
-      /* handle variable creation */
+      if (!add_variable(parsed_cmd->text, parsed_cmd->next->text)) {
+        fprintf(stderr, "ERROR: Failed to create variable\n");
+      }
       goto free_tokens;
     }
 
@@ -79,6 +110,7 @@ int main(int argc, char **argv) {
       goto free_tokens;
     }
 
+    variable_substitution(cmds);
 
     for (command *cmd = cmds; cmd; cmd = cmd->next) {
       pid_t result = execute_command(cmd);
@@ -91,9 +123,7 @@ int main(int argc, char **argv) {
 
     for (command *cmd = cmds; cmd; cmd = cmd->next) {
       if (cmd->pid > 0) {
-        fprintf(stderr, "Waiting for %d\n", cmd->pid);
         waitpid(cmd->pid, NULL, 0);
-        fprintf(stderr, "%d completed\n", cmd->pid);
       }
     }
 
@@ -107,4 +137,6 @@ int main(int argc, char **argv) {
   draw_prompt:
     fprintf(stdout, "$ ");
   }
+
+  destroy_variable_store();
 }
diff --git a/src/variables.c b/src/variables.c
new file mode 100644
index 0000000..c7cc4da
--- /dev/null
+++ b/src/variables.c
@@ -0,0 +1,57 @@
+/* 
+ *
+ */
+
+#include "variables.h"
+#include "strmap.h"
+
+static strmap *map;
+
+bool init_variable_store(void) {
+  map = strmap_create(hash_key);
+  return map;
+}
+
+bool add_variable(const char *key, const char *val) {
+  if (strmap_put(map, key, val) != STRMAP_OK) {
+    return false;
+  }
+
+  return true;
+}
+
+const char *get_variable(const char *key) {
+  fprintf(stderr, "Key is: %s\n", key);
+
+  key += (key[0] == '$');
+  const char *val;
+  strmap_status stat = strmap_get(map, key, &val);
+  switch (stat) {
+    case STRMAP_OK:
+      break;
+    case STRMAP_NOTFOUND:
+      val = getenv(key);
+      break;
+    default:
+      val = NULL;
+      break;
+  }
+
+  val = (val) ? val : "";
+  fprintf(stderr, "Value is: %s\n", val);
+
+  return val;
+}
+
+bool promote_variable_to_env(const char *key) {
+  const char *val = get_variable(key);
+  if (!val) {
+    val = "";
+  }
+
+  return !setenv(key, val, 1);
+}
+
+void destroy_variable_store() {
+  strmap_destroy(map);
+}
-- 
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