Theodore Ts'o 3658b8b339 ext4: replace strcmp with direct comparison for '.' and '..'
In a discussion over a proposed patch, "ext4: replace strcpy() with
'.' assignment"[1], I had asserted that directory entries in ext4 were
not NUL terminated, and hence it was safe to replace strcpy() with a
direct assignment.  As it turns out, this was incorrect.  It's true
for all all directory entries *except* for '.' and '..' where the
kernel was using strcmp() and where e2fsck actually checks and offers
to fix things if '.'  and '..' are not NUL terminated.

[1] https://lore.kernel.org/r/202505191316.JJMnPobO-lkp@intel.com

We can't change this without breaking old kernel versions, but in the
spirit of "be liberal in what you receive", use direct comparison of
de->name_len and de->name[0,1] instead of strcmp().  This has the side
benefit of reducing the compiled text size by 96 bytes on x86_64.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://patch.msgid.link/20250712181249.434530-1-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2025-07-17 23:25:21 -04:00
…
2025-06-21 07:34:28 -07:00
2025-02-19 14:53:27 -07:00
2025-06-29 13:09:04 -07:00
…

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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