From e58215e5e271bae899c910f04d646a65105071f6 Mon Sep 17 00:00:00 2001
From: Adam <607975+adam-vessey@users.noreply.github.com>
Date: Fri, 13 Mar 2026 19:36:24 -0300
Subject: [PATCH 1/2] Potential read issue.

Reading a single `"0"` could potentially be interpreted as a false response per PHP's truth table, resulting in returning a `null`.
---
 src/SourceResource.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/SourceResource.php b/src/SourceResource.php
index 9eaefdd..55d6caf 100644
--- a/src/SourceResource.php
+++ b/src/SourceResource.php
@@ -21,7 +21,9 @@ public function __construct($resource)
         parent::__construct();
 
         $this->onRead(static function (int $length) use (&$resource): ?string {
-            return fread($resource, $length) ?: null;
+            return (($read = fread($resource, $length)) !== '') ?
+                $read :
+                null;
         });
 
         if (stream_get_meta_data($resource)['seekable']) {

From 06066510f9fd2a66479d1d38db27bfad558f97f7 Mon Sep 17 00:00:00 2001
From: Adam <607975+adam-vessey@users.noreply.github.com>
Date: Fri, 13 Mar 2026 19:43:48 -0300
Subject: [PATCH 2/2] `fseek()` can fail.

Should `fseek()` fail, we probably want to flag the error.

https://www.libvips.org/API/8.17/vfunc.Source.seek.html#return-value seems to suggest that a `-1` would be appropriate to return in such a case?
---
 src/SourceResource.php | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/SourceResource.php b/src/SourceResource.php
index 55d6caf..73f8fd0 100644
--- a/src/SourceResource.php
+++ b/src/SourceResource.php
@@ -28,8 +28,9 @@ public function __construct($resource)
 
         if (stream_get_meta_data($resource)['seekable']) {
             $this->onSeek(static function (int $offset, int $whence) use (&$resource): int {
-                fseek($resource, $offset, $whence);
-                return ftell($resource);
+                return fseek($resource, $offset, $whence) === 0 ?
+                    ftell($resource) :
+                    -1;
             });
         }
     }