bugfix: endless loop in exif.inf parsing

This fixes an endless loop that occured when reading from an exif.inf file that starts with an empty line. Bug reported and patch to `functions/getExifDescription.php` submitted by Roland Dieterich. Many thanks to Roland! Co-authored-by: Roland Dieterich <dieterich@mpipz.mpg.de>
Boris-de · Jan 26, 2024 · 2e8107d · 2e8107d
1 parent 3b330e9
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diff --git a/docs/changelog.md b/docs/changelog.md
@@ -3,10 +3,18 @@ Mig - Changelog
 
 ## Version 1.7.2 (tbd)
 
+### Notable changes
+
+Fixed endless loop when reading from an exif.inf file that starts with an empty line.
+
 ### Other changes
 
 Fixed warnings reported by psalm and phpstorm and replaced outdated constructs.
 
+### Acknowledgements
+
+A special thanks to Roland Dieterich <dieterich@mpipz.mpg.de> for reporting and fixing the bug in the exif.inf parsing.
+
 ## Version 1.7.1 (Sat, 17 Dec 2022)
 
 ### Notable changes

diff --git a/functions/getExifDescription.php b/functions/getExifDescription.php
@@ -6,7 +6,7 @@
 function getExifDescription ( $unsafe_currDir, $formatString )
 {
     global $mig_config;
-    
+
     $aperture   = array ();
     $day        = array ();
     $desc       = array ();
@@ -22,12 +22,10 @@ function getExifDescription ( $unsafe_currDir, $formatString )
 
     $localExifFilename = $mig_config['albumdir'] . "/$unsafe_currDir/exif.inf";
     if (file_exists($localExifFilename)) {
-
         $fname = NULL;
         $file = fopen($localExifFilename, 'r');
-        $line = fgets($file, 4096);     // get first line
         while (!feof($file)) {
-
+            $line = fgets($file, 4096);
             if (strpos($line, 'File name    : ') === 0) {
                 $fname = str_replace('File name    : ', '', $line);
                 $fname = chop($fname);
@@ -103,12 +101,10 @@ function getExifDescription ( $unsafe_currDir, $formatString )
                 $day[$fname]      = $y;
                 $time[$fname]     = $z;
             }
-
-            $line = fgets($file, 4096);
         }
 
         fclose($file);
-        
+
         $unsafe_image = $mig_config['unsafe_image'];
 
         if (!isset($knownFiles[$unsafe_image])) {

diff --git a/test/GetExifDescriptionTest.php b/test/GetExifDescriptionTest.php
@@ -24,7 +24,6 @@ public function testNoExifInfo()
 
     public function test()
     {
-        global $mig_config;
         $this->set_mig_config_image('test.jpg');
         $dir = $this->album_dir . '/foo';
         $this->mkdir($dir);
@@ -55,7 +54,6 @@ public function test()
 
     public function testEmptyFile()
     {
-        global $mig_config;
         $this->set_mig_config_image('test.jpg');
         $dir = $this->album_dir . '/foo';
         $this->mkdir($dir);
@@ -64,9 +62,27 @@ public function testEmptyFile()
             getExifDescription('./foo', '%c %a %f %i %l %m %s %Y %M %D %T'));
     }
 
+    public function testOnlyNewline()
+    {
+        $this->set_mig_config_image('test.jpg');
+        $dir = $this->album_dir . '/foo';
+        $this->mkdir($dir);
+        $this->touchWithContent($dir . '/exif.inf', "\n");
+        $this->assertEquals('',
+            getExifDescription('./foo', '%c %a %f %i %l %m %s %Y %M %D %T'));
+    }
+
+    public function testContentAfterEmptyLine()
+    {
+        $this->set_mig_config_image('test.jpg');
+        $dir = $this->album_dir . '/foo';
+        $this->mkdir($dir);
+        $this->touchWithContent($dir . '/exif.inf', "\nFile name    : test.jpg\nCamera model : Canon EOS 70D");
+        $this->assertEquals('Canon EOS 70D', getExifDescription('./foo', '%m'));
+    }
+
     public function testMultipleFiles()
     {
-        global $mig_config;
         $this->touchWithContent($this->album_dir . '/exif.inf', "File name    : test1.jpg\n
 Camera model : Canon EOS 70D\n
 Date/Time    : 2013:12:05 18:37:14\n
@@ -98,7 +114,6 @@ public function testMultipleFiles()
 
     public function testFileNotInExifData()
     {
-        global $mig_config;
         $this->set_mig_config_image('not_existing.jpg');
         $dir = $this->album_dir . '/foo';
         $this->mkdir($dir);