Date: Wed, 15 Nov 2023 06:19:57 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 275099] cat(1) can't read directories Message-ID: <bug-275099-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275099 Bug ID: 275099 Summary: cat(1) can't read directories Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: bin Assignee: bugs@FreeBSD.org Reporter: msl0000023508@gmail.com Attachment #246324 text/plain mime type: Created attachment 246324 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=246324&action=edit helloworld-dir.c While it is not common to read(2) a directory directly, this is still supported in FreeBSD (with security.bsd.allow_read_dir=1); and it could be actually useful in FUSE as an user space file system implementation may provide some data in a directory itself. The followings demonstrate the issue with a FUSE-based file system: # sysctl security.bsd.allow_read_dir=1 security.bsd.allow_read_dir: 0 -> 1 # helloworld-dir /mnt/3/ # ls -al /mnt/3/ total 0 drwxr-xr-x 2 root wheel 27 Jan 1 1970 . drwxr-xr-x 2 root wheel 13 Jan 1 1970 hello # ls -al /mnt/3/hello/ total 0 drwxr-xr-x 2 root wheel 13 Jan 1 1970 . drwxr-xr-x 2 root wheel 27 Jan 1 1970 .. -rw-r--r-- 1 root wheel 12 Jan 1 1970 world # cat /mnt/3/hello/world Hello world # cat /mnt/3/hello cat: stdout: Is a directory # dd status=none if=/mnt/3/hello Hello world! # cat /mnt/3/ cat: stdout: Is a directory # dd status=none if=/mnt/3/ This is the root directory # umount /mnt/3/ It shows that cat(1) failed to read the directories but dd(1) works without problem. The cause is that cat(1) tries to use copy_file_range(2) to copy input file to stdout but this system call dosen't work on directories as documented, and cat(1) didn't fallback to read(2) and write(2) on copy_file_range(2) fail with EISDIR. The FUSE program for demonstration is attached. -- You are receiving this mail because: You are the assignee for the bug.home | help
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