commit be9fbecca88fca8099239c55c1b394bb2b4dcc72
author Benjamin Peterson <bp@benjamin.pe> Wed Mar 27 05:25:18 2019 -0700
committer Copybara-Service <copybara-worker@google.com> Wed Mar 27 05:26:37 2019 -0700
tree 40d762d93fa7a3ac6e19fe7b54e7a58b3d70bbea
parent 3bd9a105701abfad891363df9de0f5454196f6a1

Implement a native file OutputStream for Unix.

Bazel's VFS classes make the assumption that all filenames are encoded with latin-1. That theoretically allows roundtripping any sort of horrible byte pattern a Unix filesystem can produce through Bazel's Path class. This scheme falls apart, though, when trying to use the JDK I/O libraries. The filename encoding assumed by the JDK I/O libraries comes from the sun.jnu.encoding property, which can't be overriden with the normal -D JVM command line syntax. The Bazel client still tries quite hard to force this property to be latin-1: https://github.com/bazelbuild/bazel/blob/6641ad986f436926a75b31b47314c193a9a7e032/src/main/cpp/blaze.cc#L1467-L1473 But even a fusillade of 4 environmental variables is sometimes not enough. On macOS, the JDK simply hardcodes UTF-8 as sun.jnu.encoding. Even on Linux, if a the en_US.ISO-8859-1 locale isn't installed, glibc will fall back to an ASCII encoding. Since there's no public way to create a JDK FileOutputStream from either a byte[] filename or a raw file descriptor, I conclude the only workaround is to implement open() and write() in Bazel's unix_jni. This CL does that.

We should probably implement a native file InputStream, too, for completeness. However, as merely implementing OutputStream fixes the relevant issue, I'm only doing that in this CL.

Fixes https://github.com/bazelbuild/bazel/issues/7055.

Closes #7757.

PiperOrigin-RevId: 240538266

src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java

diff --git a/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java b/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
index 0098934..cca0b4b 100644
--- a/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
+++ b/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
@@ -37,9 +37,7 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
-/**
- * This class tests the FilesystemUtils class.
- */
+/** Tests for the {@link NativePosixFiles} class. */
 @RunWith(JUnit4.class)
 public class NativePosixFilesTest {
   private FileSystem testFS;
@@ -156,4 +154,30 @@
     assertThrows(
         FileNotFoundException.class, () -> NativePosixFiles.lgetxattr(nonexistentFile, "foo"));
   }
+
+  @Test
+  public void writing() throws Exception {
+    java.nio.file.Path myfile = Files.createTempFile("myfile", null);
+    int fd1 = NativePosixFiles.openWrite(myfile.toString(), false);
+    assertThrows(
+        IndexOutOfBoundsException.class,
+        () -> NativePosixFiles.write(fd1, new byte[] {0, 1, 2, 3}, 5, 1));
+    assertThrows(
+        IndexOutOfBoundsException.class,
+        () -> NativePosixFiles.write(fd1, new byte[] {0, 1, 2, 3}, -1, 1));
+    assertThrows(
+        IndexOutOfBoundsException.class,
+        () -> NativePosixFiles.write(fd1, new byte[] {0, 1, 2, 3}, 0, -1));
+    assertThrows(
+        IndexOutOfBoundsException.class,
+        () -> NativePosixFiles.write(fd1, new byte[] {0, 1, 2, 3}, 0, 5));
+    NativePosixFiles.write(fd1, new byte[] {0, 1, 2, 3}, 0, 4);
+    NativePosixFiles.close(fd1, null);
+    assertThat(Files.readAllBytes(myfile)).isEqualTo(new byte[] {0, 1, 2, 3});
+    // Try appending.
+    int fd2 = NativePosixFiles.openWrite(myfile.toString(), true);
+    NativePosixFiles.write(fd2, new byte[] {5, 6, 7, 8, 9}, 1, 3);
+    NativePosixFiles.close(fd2, null);
+    assertThat(Files.readAllBytes(myfile)).isEqualTo(new byte[] {0, 1, 2, 3, 6, 7, 8});
+  }
 }