cat is not working

[DoBi]

I've installed the new release 0.0.5 and now cat is not working any more:
Sometimes it gives me:

$ cat config.log
cat: error: EINVAL: Invalid argument

This file exists and GNU cat is working printing its content.

For some other files there is no output.
I don't know, what causes this different behaviour.
But at least cat is not working as expected.

[sylvestre]

Yeah, I noticed that too :(
I will do a 0.0.6 to fix it.

I guess it is caused by
#1978
cc @ArniDagur

We should improve the coverage:
https://codecov.io/gh/uutils/coreutils/src/master/src/uu/cat/src/cat.rs

[sylvestre]

I yanked 0.0.5 from crates.io because of this

[ArniDagur]

Well... This is embarrassing. @DoBi could you tell me:

• The output of uname -a
• Which kind of file config.log is. Is it regular? A symlink?

The tests in #2001 find this regression; that's why they fail. The weird thing is however that manually calling cat never fails for me, it only ever fails through cargo test. I will investigate further.

[sylvestre]

on a regular debian:

$ echo "foo" >> /tmp/a.xt
$ /usr/lib/cargo/bin/coreutils/cat /tmp/a.txt
$ /usr/lib/cargo/bin/coreutils/cat /tmp/a.txt|wc -c
0
$ /usr/lib/cargo/bin/coreutils/cat --version
cat 0.0.5
$ uname -a
Linux xxxx 5.10.0-1-amd64 #1 SMP Debian 5.10.4-1 (2020-12-31) x86_64 GNU/Linux

[ArniDagur]

[arni][~/src/coreutils][cat-tests]% yes | head -c16383 > 16k_minus1_file.txt
[arni][~/src/coreutils][cat-tests]% yes | head -c16384 > 16k_file.txt
[arni][~/src/coreutils][cat-tests]% yes | head -c16385 > 16k_plus1_file.txt
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_plus1_file.txt
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_plus1_file.txt | wc -c
16384
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_file.txt | wc -c
0
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_minus1_file.txt | wc -c
0
[arni][~/src/coreutils][cat-tests]% yes | head -c16387 > 16k_plus3_file.txt
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_plus3_file.txt | wc -c
16384

It seems that any file of length <= 16384 fails to print anything. That's the buffer size I used for the splice operation. I have an idea of what is wrong.

[tertsdiepraam]

@ArniDagur those tests match what's happening on my machine. It only seems to fail without options. Hope that helps!

$ echo "foo" > /tmp/a.txt
$ target/debug/coreutils cat /tmp/a.txt
$ target/debug/coreutils cat -s /tmp/a.txt
foo
$ target/debug/coreutils cat -n /tmp/a.txt
     1  foo
$ target/debug/coreutils cat -v /tmp/a.txt
foo

[ArniDagur]

wow I'm so dumb.

openat(AT_FDCWD, "16k_plus3_file.txt", O_RDONLY|O_CLOEXEC) = 3
pipe([4, 5])                            = 0
splice(3, NULL, 5, NULL, 16384, 0)      = 16384
splice(3, NULL, 5, NULL, 16384, 0)      = 3
splice(4, NULL, 1, NULL, 16384, 0)      = 16384
splice(3, NULL, 5, NULL, 16384, 0)      = 0

I'll post a fix in a minute.

[DoBi]

@ArniDagur in case you need some more info for cat: error: EINVAL: Invalid argument:

Output of uname -a:
Linux XXX 5.11.10-hardened1-1-hardened #1 SMP PREEMPT Thu, 25 Mar 2021 21:32:46 +0000 x86_64 unknown unknown GNU/Linux

It is a regular file. Output of ls -las config.log
40 -rw-r--r-- 1 <username> <groupname> 38586 3. Apr 17:02 config.log

The same error appears when executing the command on a symlink to this file.

[ArniDagur]

One line fix:

[arni][~/src/coreutils][cat-tests]% git diff | cat
diff --git a/src/uu/cat/src/cat.rs b/src/uu/cat/src/cat.rs
index f39708fd..5861e348 100644
--- a/src/uu/cat/src/cat.rs
+++ b/src/uu/cat/src/cat.rs
@@ -459,6 +459,7 @@ fn write_fast_using_splice<R: Read>(handle: &mut InputHandle<R>, writer: RawFd)
             }
         }
     }
+    splice(pipe_rd, None, writer, None, BUF_SIZE, SpliceFFlags::empty())?;

     loop {
         let n = splice(
[arni][~/src/coreutils][cat-tests]% target/release/cat 16k_plus3_file.txt | wc -c
16387
[arni][~/src/coreutils][cat-tests]% cargo test --release test_no_options
...
     Running tests/tests.rs (target/release/deps/tests-3f4336eae7fd152c)

running 2 tests
test test_cat::test_no_options ... ok
test test_cat::test_no_options_big_input ... ok

test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 764 filtered out; finished in 0.01s

[ArniDagur]

@DoBi Could you try #2020 and see if that fixes the EINVAL error?

[sylvestre]

Thanks :)
by the way, if you want to benchmark it, hyperfine is pretty good
https://github.com/sharkdp/hyperfine

[DoBi]

@DoBi Could you try #2020 and see if that fixes the EINVAL error?

Yes, it works fine with both, the regular file as well as with the symlink 👍

[sylvestre]

This issue is now fixed in tree. So, closing :)