Re: sourc. can't handle /sys/block/*/uevent on Linux

[Chet Ramey]

On 7/12/25 12:52 PM, Emanuele Torre wrote:

User zen_desu mentioned this bug report on the #bash IRC channel of
libera.chat today: https://github.com/desultory/ugrd/pull/328

Basically, in bash 5.3, if you try to source a /sys/block/*/uevent file;
example:

     $ cat /sys/block/sda/uevent
     MAJOR=8
     MINOR=0
     DEVNAME=sda
     DEVTYPE=disk
     DISKSEQ=1

source or . will fail printing the error message"bash: ${file}: Success"

Hmmmm. Let's see here.

One of the assumptions bash makes is that when the kernel tells it the size
of a regular file using stat(2), it's telling the truth, and that reading
fewer bytes than that when asking for the entire file indicates some kind
of problem.

This happens because /sys/block/*/uevent show up as regular files, and
reports a file size of 4096 in stat:

Which isn't the true file size.

..and there is a new check in evalfile_internal() that treats like an
error to not get filesize bytes after one read from a regular file
(given a large enough buffer)

Yes. It seems like that assumption isn't valid on Linux.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    c...@case.edu    http://tiswww.cwru.edu/~chet/

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