8062795: (fs) Files.setPermissions requires read access when NOFOLLOW_LINKS specified

[bplb]

If setting POSIX permissions while not following links fails with AccessDeniedException but the path does not contain any symbolic links, then retry the operation as if the NOFOLLOW_LINKS option had not been specified.

---

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Issue

• JDK-8062795: (fs) Files.setPermissions requires read access when NOFOLLOW_LINKS specified (Bug - P4)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)

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[openjdk]

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Webrevs

• 03: Full - Incremental (39b07548)
• 02: Full - Incremental (2e044467)
• 01: Full - Incremental (1cf6b36c)
• 00: Full (add38151)

[AlanBateman]

I don't think this is the right thing as it may do the wrong thing when there are concurrency changes on the file system. I think the simplest is to just attempt to open the file for write access, this should work for regular files.

Not tested, but I expect something like this is what you want here.

diff --git a/src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java b/src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java
index f35541a9e19..bcab5319d8d 100644
--- a/src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java
+++ b/src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java
@@ -31,6 +31,7 @@ import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.io.IOException;
 
+import static sun.nio.fs.UnixConstants.*;
 import static sun.nio.fs.UnixNativeDispatcher.*;
 
 class UnixFileAttributeViews {
@@ -262,20 +263,45 @@ class UnixFileAttributeViews {
         // chmod
         final void setMode(int mode) throws IOException {
             checkWriteExtended();
-            try {
-                if (followLinks) {
+
+            if (followLinks) {
+                try {
                     chmod(file, mode);
-                } else {
-                    int fd = file.openForAttributeAccess(false);
+                } catch (UnixException e) {
+                    e.rethrowAsIOException(file);
+                }
+                return;
+            }
+
+            if (O_NOFOLLOW == 0) {
+                throw new IOException("NOFOLLOW_LINKS is not supported on this platform");
+            }
+
+            int fd = -1;
+            try {
+                fd = open(file, O_RDONLY, O_NOFOLLOW);
+            } catch (UnixException e1) {
+                if (e1.errno() == EACCES) {
                     try {
-                        fchmod(fd, mode);
-                    } finally {
-                        close(fd);
+                        fd = open(file, O_WRONLY, O_NOFOLLOW);
+                    } catch (UnixException e2) {
+                        e2.rethrowAsIOException(file);
                     }
+                } else {
+                    e1.rethrowAsIOException(file);
                 }
-            } catch (UnixException x) {
-                x.rethrowAsIOException(file);
             }
+
+            try {
+                try {
+                    fchmod(fd, mode);
+                } finally {
+                    close(fd);
+                }
+            } catch (UnixException e) {
+                e.rethrowAsIOException(file);
+            }
+
         }
 
         // chown

[bplb]

I think the simplest is to just attempt to open the file for write access [...].

This in fact works. So changed in 2e04446.

[openjdk]

@bplb This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8062795: (fs) Files.setPermissions requires read access when NOFOLLOW_LINKS specified

Reviewed-by: alanb

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 98 new commits pushed to the master branch:

• 13f6450: 8313765: Invalid CEN header (invalid zip64 extra data field size)
• 24e896d: 8310275: Bug in assignment operator of ReservedMemoryRegion
• 1925508: 8314144: gc/g1/ihop/TestIHOPStatic.java fails due to extra concurrent mark with -Xcomp
• b80001d: 8314209: Wrong @SInCE tag for RandomGenerator::equiDoubles
• ef6db5c: 8314211: Add NativeLibraryUnload event
• 49ddb19: 8313760: [REDO] Enhance AES performance
• d46f0fb: 8313720: C2 SuperWord: wrong result with -XX:+UseVectorCmov -XX:+UseCMoveUnconditionally
• 38687f1: 8314262: GHA: Cut down cross-compilation sysroots deeper
• a602624: 8314020: Print instruction blocks in byte units
• 0b12480: 8314233: C2: assert(assertion_predicate_has_loop_opaque_node(iff)) failed: unexpected
• ... and 88 more: https://git.openjdk.org/jdk/compare/515add88ed6c290ee90f3d6f522a22971e37a62c...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[bplb]

/integrate

[openjdk]

Going to push as commit 6b396da.
Since your change was applied there have been 100 commits pushed to the master branch:

• 7b28d36: 8314330: java/foreign tests should respect vm flags when start new processes
• b32d641: 8311943: Cleanup usages of toLowerCase() and toUpperCase() in java.base
• 13f6450: 8313765: Invalid CEN header (invalid zip64 extra data field size)
• 24e896d: 8310275: Bug in assignment operator of ReservedMemoryRegion
• 1925508: 8314144: gc/g1/ihop/TestIHOPStatic.java fails due to extra concurrent mark with -Xcomp
• b80001d: 8314209: Wrong @SInCE tag for RandomGenerator::equiDoubles
• ef6db5c: 8314211: Add NativeLibraryUnload event
• 49ddb19: 8313760: [REDO] Enhance AES performance
• d46f0fb: 8313720: C2 SuperWord: wrong result with -XX:+UseVectorCmov -XX:+UseCMoveUnconditionally
• 38687f1: 8314262: GHA: Cut down cross-compilation sysroots deeper
• ... and 90 more: https://git.openjdk.org/jdk/compare/515add88ed6c290ee90f3d6f522a22971e37a62c...master

Your commit was automatically rebased without conflicts.

[openjdk]

@bplb Pushed as commit 6b396da.

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