Fwd: Bug#1015273: coreutils: rm -d doesn't try to remove unreadable directories, lies in error message, with *fails to prompt* with -i

[Jim Meyering]

---------- Forwarded message ---------
From: Jim Meyering <jim@meyering.net>
Date: Mon, Feb 20, 2023 at 6:27 PM
Subject: Re: Bug#1015273: coreutils: rm -d doesn't try to remove
unreadable directories, lies in error message, with *fails to prompt*
with -i
To: наб <nabijaczleweli@nabijaczleweli.xyz>, <1015273@bugs.debian.org>
Cc: Debian Bug Tracking System <submit@bugs.debian.org>

On Mon, Jul 18, 2022 at 12:21 PM наб <nabijaczleweli@nabijaczleweli.xyz> wrote:
> Package: coreutils
> Version: 8.32-4.1
> Severity: normal
>
> Dear Maintainer,
>
> Fun one for ya: the baseline:
> -- >8 --
> $ mkdir -p /tmp/psko
> $ rm -vid /tmp/psko
> rm: remove directory '/tmp/psko'? y
> removed directory '/tmp/psko'
> -- >8 --
>
> Bug a:
> -- >8 --
> $ mkdir -p /tmp/psko
> $ chmod -r /tmp/psko
> $ rm -vid /tmp/psko; echo $?
> rm: cannot remove '/tmp/psko': Directory not empty
> 1
> -- >8 --
>
> Absolutely 0 prompt, despite -i!
> That's very fun (and a POSIX violation)!
>
> Bug b:
> -- >8 --
> $ strace rm -vid /tmp/psko 2>&1 | grep -v locale
> execve("/bin/rm", ["rm", "-vid", "/tmp/psko"], 0xff8fbc48 /* 24 vars */) = 0
> /* ... */
> arch_prctl(ARCH_SET_FS, 0xf7f9e240)     = 0
> mprotect(0xf7f8b000, 8192, PROT_READ)   = 0
> mprotect(0x40f000, 4096, PROT_READ)     = 0
> mprotect(0xf7fcd000, 8192, PROT_READ)   = 0
> munmap(0xf7f96000, 26859)               = 0
> brk(NULL)                               = 0xaa6000
> brk(0xac7000)                           = 0xac7000
> brk(0xac8000)                           = 0xac8000
> newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=3041504, ...}, 
> AT_EMPTY_PATH) = 0
> mmap(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xf7a00000
> mmap(NULL, 2596864, PROT_READ, MAP_PRIVATE, 3, 0x6d000) = 0xf7786000
> close(3)                                = 0
> ioctl(0, TCGETS, {B38400 opost isig icanon echo ...}) = 0
> newfstatat(AT_FDCWD, "/tmp/psko", {st_mode=S_IFDIR|0311, st_size=40, ...}, 
> AT_SYMLINK_NOFOLLOW) = 0
> openat(AT_FDCWD, "/tmp/psko", 
> O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_DIRECTORY) = -1 EACCES (Permission 
> denied)
> newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=2996, ...}, AT_EMPTY_PATH) = > 0
> read(3, "# Locale name alias data base.\n#"..., 4096) = 2996
> read(3, "", 4096)                       = 0
> close(3)                                = 0
> write(2, "rm: ", 4rm: )                     = 4
> write(2, "cannot remove '/tmp/psko'", 25cannot remove '/tmp/psko') = 25
> newfstatat(3, "", {st_mode=S_IFREG|0644, st_size=1433, ...}, AT_EMPTY_PATH) = > 0
> mmap(NULL, 1433, PROT_READ, MAP_PRIVATE, 3, 0) = 0xf7f9c000
> close(3)                                = 0
> write(2, ": Directory not empty", 21: Directory not empty)   = 21
> write(2, "\n", 1
> )                       = 1
> lseek(0, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
> close(0)                                = 0
> close(1)                                = 0
> close(2)                                = 0
> exit_group(1)                           = ?
> +++ exited with 1 +++
> -- >8 --
>
> Can you spot a rmdir(2) equivalent? I can't! So why does it lie and say
> that it tried to remove it?
>
> Also, the directory /isn't nonempty/! Bug c:
> -- >8 --
> $ rmdir -v /tmp/psko/; echo $?
> rmdir: removing directory, '/tmp/psko/'
> 0
> -- >8 --
> And it's not there! Because, shockingly, there's nothing stopping you
> from removing it! So why on /earth/ is rm failing to prompt, failing to
> try to remove it, then lying that it had and failed with an obviously
> false errno?
>
> The same applies to just plain rm -d /tmp/psko (no -i)
> (except for bug a).

Thank you for the bug report.
I've attached a patch that fixes those bugs.

rm--dir.diff
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