[GH-526] Reading named pipes with Java posix fails with Illegal seek

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/test_posix.py

@@ -173,6 +173,31 @@ def test_pipe(self):
             os.close(fd1)
             os.close(fd2)
 
+    @unittest.skipIf(sys.platform != 'linux', 'mkfifo is a linux command')
+    def test_seek_pipe(self):
+        new_file_path = './myscript.sh'
+        with io.open(new_file_path, 'w') as script:
+            script.write("""#!/bin/sh
+            mkfifo testpipe
+            echo "4" > testpipe &
+            """)
+        try:
+            st = os.stat(new_file_path)
+            os.chmod(new_file_path, st.st_mode | stat.S_IEXEC)
+            os.system(new_file_path)
+            with io.open("testpipe", "rb") as r:
+                out = r.read(1)
+            assert out == b"4", out
+        finally:
+            try:
+                os.remove(new_file_path)
+            except:
+                pass
+            try:
+                os.remove("testpipe")
+            except:
+                pass
+
     def test_mkdir_rmdir(self):
         os.mkdir(TEST_FULL_PATH1)
         try:

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/exception/OSErrorEnum.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0
@@ -312,7 +312,7 @@ public static ErrorAndMessagePair fromException(Exception e, TruffleString.Equal
                     return new ErrorAndMessagePair(oserror, oserror.getMessage());
                 }
             } else { // Generic IOException
-                OSErrorEnum oserror = tryFindErrnoFromMessage(e);
+                OSErrorEnum oserror = tryFindErrnoFromMessage(e, eqNode);
                 if (oserror == null) {
                     return new ErrorAndMessagePair(OSErrorEnum.EIO, getMessage(e));
                 } else {
@@ -360,15 +360,13 @@ private static TruffleString getReason(FileSystemException e) {
     }
 
     @TruffleBoundary
-    private static OSErrorEnum tryFindErrnoFromMessage(Exception e) {
-        if (e.getMessage().contains("Broken pipe")) {
-            return OSErrorEnum.EPIPE;
-        }
-        Matcher m = ERRNO_PATTERN.matcher(e.getMessage());
+    private static OSErrorEnum tryFindErrnoFromMessage(Exception e, TruffleString.EqualNode eqNode) {
+        String message = e.getMessage();
+        Matcher m = ERRNO_PATTERN.matcher(message);
         if (m.find()) {
             return fromNumber(Integer.parseInt(m.group(1)));
         }
-        return null;
+        return OSErrorEnum.fromMessage(toTruffleStringUncached(message), eqNode);
     }
 
     @ValueType

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/EmulatedPosixSupport.java

@@ -527,10 +527,15 @@ public Buffer read(int fd, long length,
     }
 
     @TruffleBoundary
-    private static Buffer readBytesFromChannel(ReadableByteChannel channel, long size) throws IOException {
+    private static Buffer readBytesFromChannel(ReadableByteChannel channel, long sizeIn) throws IOException {
+        long size = sizeIn;
         if (channel instanceof SeekableByteChannel seekableByteChannel) {
-            long availableSize = seekableByteChannel.size() - seekableByteChannel.position();
-            size = Math.min(size, availableSize);
+            try {
+                long availableSize = seekableByteChannel.size() - seekableByteChannel.position();
+                size = Math.min(size, availableSize);
+            } catch (IOException e) {
+                // pass and read what we can
+            }
         }
         size = Math.min(size, MAX_READ);
         ByteBuffer dst = ByteBuffer.allocate((int) size);