Prevent race condition in executable "generation"

a-schild · Sep 3, 2021 · 5cec8b1 · naffan2014 · Sep 3, 2021 · 5cec8b1
1 parent a5b98d6
commit 5cec8b1
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Showing 2 changed files with 19 additions and 15 deletions.
diff --git a/Changelog.md b/Changelog.md
@@ -10,6 +10,7 @@
    - Added constructor for color filter which allows string expressions
    - Added support for multiple video filters in one conversion pass
    - Added enhanced meta data detection in MultiMedia object
+   - Implement critical section in executable location+creation to prevent race condition (Issue #163)
 - **3.1.0**
    - Added support for arm32 bit (Thanks to jmformenti)
    - Added option to use a specific quote character for command line

diff --git a/jave-core/src/main/java/ws/schild/jave/process/ffmpeg/DefaultFFMPEGLocator.java b/jave-core/src/main/java/ws/schild/jave/process/ffmpeg/DefaultFFMPEGLocator.java
@@ -71,22 +71,25 @@ public DefaultFFMPEGLocator() {
     File ffmpegFile = new File(dirFolder, "ffmpeg-" + arch + "-" + Version.getVersion() + suffix);
     LOG.debug("Executable path: {}", ffmpegFile.getAbsolutePath());
 
-    // Check the version of existing .exe file
-    if (ffmpegFile.exists()) {
-      // OK, already present
-      LOG.debug("Executable exists in <{}>", ffmpegFile.getAbsolutePath());
-    } else {
-      LOG.debug("Need to copy executable to <{}>", ffmpegFile.getAbsolutePath());
-      copyFile("ffmpeg-" + arch + suffix, ffmpegFile);
-    }
+    synchronized(this)
+    {
+        // Check the version of existing .exe file
+        if (ffmpegFile.exists()) {
+          // OK, already present
+          LOG.debug("Executable exists in <{}>", ffmpegFile.getAbsolutePath());
+        } else {
+          LOG.debug("Need to copy executable to <{}>", ffmpegFile.getAbsolutePath());
+          copyFile("ffmpeg-" + arch + suffix, ffmpegFile);
+        }
 
-    // Need a chmod?
-    if (!isWindows) {
-      try {
-        Runtime.getRuntime().exec(new String[] {"/bin/chmod", "755", ffmpegFile.getAbsolutePath()});
-      } catch (IOException e) {
-        LOG.error("Error setting executable via chmod", e);
-      }
+        // Need a chmod?
+        if (!isWindows) {
+          try {
+            Runtime.getRuntime().exec(new String[] {"/bin/chmod", "755", ffmpegFile.getAbsolutePath()});
+          } catch (IOException e) {
+            LOG.error("Error setting executable via chmod", e);
+          }
+        }
     }
 
     // Everything seems okay