From a7393edb53560cfafb213eaf9e6d11af55c33047 Mon Sep 17 00:00:00 2001
From: onelin <oscar@nelin.dk>
Date: Tue, 22 Sep 2026 22:46:24 +0200
Subject: Fix off-by-one allocation and 0-terminating buffer, amongst memory
 cleanup

---
 main.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

(limited to 'main.c')

diff --git a/main.c b/main.c
index 5db1a7f..db86d05 100644
--- a/main.c
+++ b/main.c
@@ -90,6 +90,8 @@ main(int argc, char* argv[]) {
     // auxilliary structure to keep track of the lines, used for debugging
     // -- maybe turn off with a flag?
     line_offsets_t* lines = NULL;
+    // Resulting AST representing an arithmetic expression
+    AExp_t* expression    = NULL;
 
     srcfile               = fopen(argv[1], "re");
     if (srcfile == NULL) {
@@ -130,6 +132,9 @@ main(int argc, char* argv[]) {
     if (contents != NULL) {
       free(contents);
     }
+    if (expression != NULL) {
+      free(expression);
+    }
   }
   return 0;
 }
@@ -150,7 +155,7 @@ f_read(FILE* restrict stream, char** restrict dst) {
   }
 
   if (dst != NULL && *dst == NULL && file_sz > 0) {
-    *dst = (char*)malloc(file_sz * sizeof(char));
+    *dst = (char*)malloc((file_sz + 1) * sizeof(char));
   }
 
   if (dst != NULL && *dst == NULL && file_sz > 0) {
@@ -160,7 +165,8 @@ f_read(FILE* restrict stream, char** restrict dst) {
 
   usize bytes_read = 0;
   if (dst != NULL && *dst != NULL && file_sz > 0) {
-    bytes_read = fread(*dst, sizeof(char), file_sz, stream);
+    bytes_read      = fread(*dst, sizeof(char), file_sz, stream);
+    dst[bytes_read] = 0;
   }
 
   if (bytes_read < file_sz && feof(stream)) {
@@ -325,7 +331,7 @@ l_read(char const* restrict text, usize text_length,
 
 static AExp_t*
 p_arith(char const* restrict text, TokenList_t* restrict tokens) {
-  i64 exp_idx          = 0;
+  i64 exp_idx          = 1;
   // "groups" or parenthesized expressions
   // i64 groups           = 0;
 
@@ -418,7 +424,11 @@ p_arith(char const* restrict text, TokenList_t* restrict tokens) {
       exp_idx++;
     }
   }
-  return exp;
+
+  // We store the "root" as the first element, returning a pointer to the
+  // beginning of the memory also makes it much easier to free.
+  expression[0] = *exp;
+  return expression;
 }
 
 static AExp_t
-- 
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