From a30e675f56ca6803b2940281ec79cccb97fcd9a8 Mon Sep 17 00:00:00 2001
From: Lucas Trzesniewski <lucas.trzesniewski@gmail.com>
Date: Sun, 6 Oct 2024 16:26:44 +0200
Subject: [PATCH] Reduce number of calls to pcre2_substitute

---
 src/PCRE.NET.Native/pcrenet_substitute.c      | 9 +++++++--
 src/PCRE.NET.Tests/PcreNet/SubstituteTests.cs | 6 +++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/PCRE.NET.Native/pcrenet_substitute.c b/src/PCRE.NET.Native/pcrenet_substitute.c
index 49f1095..c2b0823 100644
--- a/src/PCRE.NET.Native/pcrenet_substitute.c
+++ b/src/PCRE.NET.Native/pcrenet_substitute.c
@@ -41,6 +41,11 @@ typedef struct
     replay_queue callout_queue;
 } substitute_callout_data;
 
+static size_t max_size(const size_t a, const size_t b)
+{
+    return a > b ? a : b;
+}
+
 static void replay_queue_init(replay_queue* queue)
 {
     queue->buffer = NULL;
@@ -83,7 +88,7 @@ static void replay_queue_try_enqueue(replay_queue* queue, uint8_t result)
 
     if (queue->count == queue->buffer_size)
     {
-        const size_t new_size = max(64, 2 * queue->buffer_size);
+        const size_t new_size = max_size(64, 2 * queue->buffer_size);
         uint8_t* new_buf = realloc(queue->buffer, new_size * sizeof(uint8_t));
         if (!new_buf)
             return;
@@ -279,7 +284,7 @@ static void substitute_with_callout(const pcrenet_substitute_input* input,
         // Output buffer is too small
         if (result->result_code == PCRE2_ERROR_NOMEMORY)
         {
-            buffer_length *= 2;
+            buffer_length = max_size(2 * buffer_length, 2 * (size_t)input->subject_length);
 
             if (!result->output_on_heap)
             {
diff --git a/src/PCRE.NET.Tests/PcreNet/SubstituteTests.cs b/src/PCRE.NET.Tests/PcreNet/SubstituteTests.cs
index 3fd0dd0..72b1078 100644
--- a/src/PCRE.NET.Tests/PcreNet/SubstituteTests.cs
+++ b/src/PCRE.NET.Tests/PcreNet/SubstituteTests.cs
@@ -265,7 +265,7 @@ public void should_execute_each_callout_once()
 
         var execCount = 0;
 
-        var result = re.InternalRegex.Substitute(str.AsSpan(), null, "#".AsSpan(), PcreMatchSettings.Default, 0, (uint)PcreSubstituteOptions.SubstituteGlobal, data =>
+        var result = re.InternalRegex.Substitute(str.AsSpan(), null, "#:#:#:#".AsSpan(), PcreMatchSettings.Default, 0, (uint)PcreSubstituteOptions.SubstituteGlobal, data =>
         {
             ++execCount;
             Assert.That(data.SubstitutionCount, Is.EqualTo(execCount));
@@ -274,8 +274,8 @@ public void should_execute_each_callout_once()
         }, out var substituteCallCount);
 
         Assert.That(execCount, Is.EqualTo(str.Length));
-        Assert.That(result, Is.EqualTo(str.Replace("aaa", "aa#")));
-        Assert.That(substituteCallCount, Is.EqualTo(6));
+        Assert.That(result, Is.EqualTo(str.Replace("aaa", "aa#:#:#:#")));
+        Assert.That(substituteCallCount, Is.EqualTo(3));
     }
 
     [Test]