Merge pull request #59441 from qgis/backport-59429-to-release-3_40

[Backport release-3_40] Use faster method to determine open file count

src/core/qgsfileutils.cpp

@@ -30,6 +30,7 @@
 // For getrlimit()
 #include <sys/resource.h>
 #include <sys/time.h>
+#include <dirent.h>
 #endif
 
 #ifdef _MSC_VER
@@ -561,10 +562,21 @@ int QgsFileUtils::openedFileLimit()
 int QgsFileUtils::openedFileCount()
 {
 #ifdef Q_OS_LINUX
-  int res = static_cast<int>( QDir( "/proc/self/fd" ).entryList().size() );
-  if ( res == 0 )
-    res = -1;
-  return res;
+  int fileCount = 0;
+
+  DIR *dirp = opendir( "/proc/self/fd" );
+  if ( !dirp )
+    return -1;
+
+  while ( struct dirent *entry = readdir( dirp ) )
+  {
+    if ( entry->d_type == DT_REG )
+    {
+      fileCount++;
+    }
+  }
+  closedir( dirp );
+  return fileCount;
 #else
   return -1;
 #endif