JRuby File.lstat (and possibly others) Raise Errno::ENOENT Instead of Errno::EACCES on Linux

Weirdly enough, we explicitly raise ENOENT for all stat/lstat return values < 0. Easy fix: don't raise anything from lstat and just return the value; consumers can then handle errno properly.

Also fstat.

Ok, I fixed this in jnr-posix, but we're behind master now. We need to pull in the newer versions or branch off from 1.1.8 for JRuby 1.6.x.

commit 6e4f3fb479cde83c668bd2e117a7e4f377228eeb
Author: Charles Oliver Nutter <headius@headius.com>
Date: Wed Aug 24 21:14:23 2011 -0500

Fix JRUBY-6021: JRuby File.lstat (and possibly others) Raise Errno::ENOENT Instead of Errno::EACCES on Linux

• fstat, lstat, and stat were hardcoded to always raise ENOENT regardless of the actual errno.

This is also fixed on 1.6 branch pending new release of jnr-posix (one used for 1.6.x). A temporary version of jnr-posix.jar is committed here until formal release of new jnr-posix. Keeping open to remember to release new jnr-posix (still waiting on another fix before new release).

Still broken in 1.7 preview?

user@host ~
> touch /tmp/foo/bar
user@host ~
> chmod ugo-x /tmp/foo
user@host ~
> irb
jruby-1.7.0.preview1 :001 > dir = "/tmp/foo"
 => "/tmp/foo" 
jruby-1.7.0.preview1 :002 > File.lstat dir
 => #<File::Stat dev=0x801, ino=753666, mode=040644, nlink=2, uid=4473, gid=1015, rdev=0x0, size=4096, blksize=4096, blocks=8, atime=2012-05-23 08:07:15 +1200, mtime=2012-05-24 09:01:03 +1200, ctime=2012-05-24 09:01:09 +1200> 
jruby-1.7.0.preview1 :003 > Dir.foreach(dir) {|e| File.lstat File.join(dir, e)}
Errno::ENOENT: No such file or directory - /tmp/foo/.
	from org/jruby/RubyFile.java:772:in `lstat'
	from (irb):3:in `evaluate'
	from org/jruby/RubyDir.java:528:in `foreach'
	from (irb):3:in `evaluate'
	from org/jruby/RubyKernel.java:1037:in `eval'
	from org/jruby/RubyKernel.java:1353:in `loop'
	from org/jruby/RubyKernel.java:1146:in `catch'
	from org/jruby/RubyKernel.java:1146:in `catch'
	from ~/.rvm/rubies/jruby-1.7.0.preview1/bin/irb:17:in `(root)'

I've just installed jruby-1.7.0 via rvm (2012/10/23) and this issue still exists. Is the jnr-posix with the fix for this bundled with jruby, or do I need to get it separately?

Does appear to be broken, assuming this behavior is broken:

headius@headius-Server:~/jruby$ bin/jruby -e "Dir.foreach('/tmp/foo') {|e| p e; begin; File.lstat File.join('/tmp/foo', e); rescue => e; p e; end}"
"."
#<Errno::ENOENT: No such file or directory - /tmp/foo/.>
".."
#<Errno::ENOENT: No such file or directory - /tmp/foo/..>
"bar"
#<Errno::ENOENT: No such file or directory - /tmp/foo/bar>

headius@headius-Server:~/jruby$ ruby -v -e "Dir.foreach('/tmp/foo') {|e| p e; begin; File.lstat File.join('/tmp/foo', e); rescue => e; p e; end}"
ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
"bar"
#<Errno::EACCES: Permission denied - /tmp/foo/bar>
".."
#<Errno::EACCES: Permission denied - /tmp/foo/..>
"."
#<Errno::EACCES: Permission denied - /tmp/foo/.>

What's strange is that we do appear to be using errno to get the last error.

Strange. Yes I would say that behaviour is broken.

Put it this way ...

> stat /tmp/foo/bar
stat: cannot stat `/tmp/foo/bar': Permission denied

... 'Permission denied', not 'No such file or directory'

It works correctly on OS X...

system ~/projects/jruby $ bin/jruby -e "Dir.foreach('/tmp/foo') {|e| p e; begin; File.lstat File.join('/tmp/foo', e); rescue => e; p e; end}"
"."
#<Errno::EACCES: Permission denied - /tmp/foo/.>
".."
#<Errno::EACCES: Permission denied - /tmp/foo/..>
"bar"
#<Errno::EACCES: Permission denied - /tmp/foo/bar>

system ~/projects/jruby $ ls -ld /tmp/foo
drw-r--r--  2 headius  wheel  102 Oct 26 22:07 /tmp/foo

I suspect we have a bad errno value in the constants for Linux. Investigating further.

So far no leads...it appears that errno 2 is mapped correctly to ENOENT and errno 13 (I think) is mapped to EACCESS, so we definitely seem to be getting ENOENT. I wonder if MRI has some special logic here...

I found the problem. We do a pre-check before actually calling stat/lstat that raises ENOENT if the JVM can't locate the file. Because the JVM is kinda stupid about the other errno reasons, this masks the real errno.

I will try to fix this.

Bleh, false alarm...the ENOENT I found is only used for bogus filenames like null, "", or if JVM security prevents accessing the filesystem. I have confirmed it's actually getting to the lstat call by dumping a real Java backtrace:

Errno::ENOENT: No such file or directory - /tmp/foo/.
      getStackTrace at java/lang/Thread.java:1495
   getBacktraceData at org/jruby/runtime/backtrace/TraceType.java:171
       getBacktrace at org/jruby/runtime/backtrace/TraceType.java:39
   prepareBacktrace at org/jruby/RubyException.java:213
           preRaise at org/jruby/exceptions/RaiseException.java:214
           preRaise at org/jruby/exceptions/RaiseException.java:195
             <init> at org/jruby/exceptions/RaiseException.java:112
  newRaiseException at org/jruby/Ruby.java:3552
    newErrnoFromInt at org/jruby/Ruby.java:3327
              error at org/jruby/ext/JRubyPOSIXHandler.java:34
              lstat at jnr/posix/LinuxPOSIX.java:82
              lstat at jnr/posix/LazyPOSIX.java:199
              setup at org/jruby/RubyFileStat.java:158
        newFileStat at org/jruby/RubyFileStat.java:92
        newFileStat at org/jruby/Ruby.java:3016
              lstat at org/jruby/RubyFile.java:774
       cacheAndCall at org/jruby/runtime/callsite/CachingCallSite.java:326
               call at org/jruby/runtime/callsite/CachingCallSite.java:170
             (root) at -e:1
             (root) at ruby/-e:1
          runScript at org/jruby/Ruby.java:776
          runScript at org/jruby/Ruby.java:769
        runNormally at org/jruby/Ruby.java:646
        runFromMain at org/jruby/Ruby.java:495
      doRunFromMain at org/jruby/Main.java:375
        internalRun at org/jruby/Main.java:264
                run at org/jruby/Main.java:230
                run at org/jruby/Main.java:214
               main at org/jruby/Main.java:194

It looks like this is fixed in JRuby 1.7.1 and continues to work in JRuby 1.7.2:

$ rvm jruby-1.7.0,jruby-1.7.1,jruby-1.7.2 --verbose do ruby -e "Dir.foreach('/tmp/foo')

"
jruby-1.7.0: jruby 1.7.0 (1.9.3p203) 2012-10-22 ff1ebbe on OpenJDK 64-Bit Server VM 1.7.0_09-b30 [linux-amd64]
"."
#<Errno::ENOENT: No such file or directory - /tmp/foo/.>
".."
#<Errno::ENOENT: No such file or directory - /tmp/foo/..>
"bar"
#<Errno::ENOENT: No such file or directory - /tmp/foo/bar>
jruby-1.7.1: jruby 1.7.1 (1.9.3p327) 2012-12-03 30a153b on OpenJDK 64-Bit Server VM 1.7.0_09-b30 [linux-amd64]
"."
#<Errno::EACCES: Permission denied - /tmp/foo/.>
".."
#<Errno::EACCES: Permission denied - /tmp/foo/..>
"bar"
#<Errno::EACCES: Permission denied - /tmp/foo/bar>
jruby-1.7.2: jruby 1.7.2 (1.9.3p327) 2013-01-04 302c706 on OpenJDK 64-Bit Server VM 1.7.0_09-b30 [linux-amd64]
"."
#<Errno::EACCES: Permission denied - /tmp/foo/.>
".."
#<Errno::EACCES: Permission denied - /tmp/foo/..>
"bar"
#<Errno::EACCES: Permission denied - /tmp/foo/bar>