From 46fd8f585cf4ce8cb4ae163e445bd44ce1e456b4 Mon Sep 17 00:00:00 2001
From: Emil Lerch <emil@lerch.org>
Date: Wed, 24 Sep 2025 10:31:34 -0700
Subject: [PATCH] avoid memory corruption with multiple replacements, deinit
 fixes, clean up output

---
 src/root.zig | 37 +++++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/src/root.zig b/src/root.zig
index 753df65..fd98a36 100644
--- a/src/root.zig
+++ b/src/root.zig
@@ -365,7 +365,7 @@ pub const Parser = struct {
     /// sentenceObject and sentenceAction will return non-zero results. If that
     /// condition cannot be satisfied, error.NoValidParse will be returned
     pub fn adaptiveParse(self: *Parser, sentence: [:0]const u8, replacements: std.StaticStringMap([]const u8)) !ParseTree {
-        var altered_buf: [1024]u8 = undefined;
+        var final_buf: [1024]u8 = undefined;
 
         const replacement_keys = replacements.keys();
         const replacement_values = replacements.values();
@@ -374,6 +374,7 @@ pub const Parser = struct {
 
         // Step 1: Replacements
         for (replacement_keys, replacement_values) |key, value| {
+            var altered_buf: [1024]u8 = undefined;
             const altered_size = std.mem.replacementSize(
                 u8,
                 altered,
@@ -394,7 +395,8 @@ pub const Parser = struct {
             );
 
             altered_buf[altered_size] = 0; // add sentinel
-            altered = altered_buf[0..altered_size :0];
+            @memcpy(final_buf[0 .. altered_size + 1], altered_buf[0 .. altered_size + 1]);
+            altered = final_buf[0..altered_size :0];
 
             if (replacement_count > 0)
                 // we have altered the deal. Pray we don't alter it further
@@ -406,13 +408,19 @@ pub const Parser = struct {
                 });
         }
         var tree = self.parse(altered) catch |err| {
-            if (shouldLog())
-                std.log.err("Failed to parse sentence: {}\n\t{s}", .{ err, altered });
+            if (shouldLog()) {
+                if (altered.len > 0)
+                    std.log.err("Failed to parse sentence: {}\n\t{s}", .{ err, altered })
+                else
+                    std.log.err("Sentence is empty: not parsing", .{});
+            }
             // continue;
             return err;
         };
+        var tree_ptr: ?*ParseTree = &tree;
+        errdefer if (tree_ptr) |p| p.deinit();
 
-        std.log.debug("adaptiveParse (step 1 - replacements):\n\toriginal:\n\t\t{s}\n\taltered:\n\t\t{s}\n{f}", .{
+        std.log.debug("adaptiveCommandParse (step 1 - replacements):\n\toriginal:\n\t\t{s}\n\taltered:\n\t\t{s}\n{f}", .{
             sentence,
             altered,
             tree,
@@ -424,6 +432,7 @@ pub const Parser = struct {
             nulls_removed = false;
             for (tree.words) |word| {
                 if (std.mem.indexOf(u8, word, "[?]")) |i| {
+                    var altered_buf: [1024]u8 = undefined;
                     nulls_removed = true;
                     // We need to alter this further
                     const trimmed = word[0..i];
@@ -436,8 +445,13 @@ pub const Parser = struct {
                     );
                     const len = altered.len - (removals * trimmed.len);
                     altered_buf[len] = 0;
-                    altered = altered_buf[0..len :0];
+                    @memcpy(final_buf[0 .. len + 1], altered_buf[0 .. len + 1]);
+                    altered = final_buf[0..len :0];
 
+                    if (altered.len == 0) {
+                        std.log.info("Removed null word '{s}' in sentence {d} time(s). Sentence now empty", .{ trimmed, removals });
+                        return error.SentenceEmptyAfterNullRemoval;
+                    }
                     std.log.info("Removed null word '{s}' in sentence {d} time(s). Sentence now:\n\t{s}", .{
                         trimmed,
                         removals,
@@ -446,11 +460,13 @@ pub const Parser = struct {
                     // Retry parsing with the word removed
                     tree.deinit();
                     tree = self.parse(altered) catch |err| {
+                        tree_ptr = null;
                         if (shouldLog())
                             std.log.err("Failed to parse altered sentence: {}\n\t{s}", .{ err, altered });
                         // continue;
                         return err;
                     };
+                    tree_ptr = &tree;
                     break; // we will remove these words conservatively...
                 }
             }
@@ -475,9 +491,9 @@ pub const Parser = struct {
 
         // Validate that we can extract action and object before returning
         const action_words = tree.sentenceAction() catch |err| {
-            if (shouldLog())
-                std.log.err("Failed to extract action: {}\n", .{err});
-            tree.deinit();
+            // This is the first catch, so we don't want to log here as it
+            // gets super noisy
+            std.log.debug("Failed to extract action: {}\n", .{err});
             return err;
             // continue;
         };
@@ -485,7 +501,6 @@ pub const Parser = struct {
 
         if (action_words.len == 0) {
             std.log.info("Failed to extract action from sentence", .{});
-            tree.deinit();
             return error.SentenceActionNotFound;
             // continue;
         }
@@ -493,7 +508,6 @@ pub const Parser = struct {
         const object_words = tree.sentenceObject() catch |err| {
             if (shouldLog())
                 std.log.err("Failed to extract object: {}\n", .{err});
-            tree.deinit();
             // continue;
             return err;
         };
@@ -501,7 +515,6 @@ pub const Parser = struct {
 
         if (object_words.len == 0) {
             std.log.info("Failed to extract object from sentence", .{});
-            tree.deinit();
             // continue;
             return error.SentenceObjectNotFound;
         }