From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 8 Mar 2021 21:43:07 +0000 (+0100)
Subject: docs: document not to use FILENAME_MAX in our codebase
X-Git-Tag: v248-rc3~24^2~4
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b775b1828df8d3ee53e8706cc8ca3d0b8726a621;p=thirdparty%2Fsystemd.git

docs: document not to use FILENAME_MAX in our codebase

It's a weird thing. Let's explain why.
---

diff --git a/docs/CODING_STYLE.md b/docs/CODING_STYLE.md
index 851676bc2bd..c15dc1abf7c 100644
--- a/docs/CODING_STYLE.md
+++ b/docs/CODING_STYLE.md
@@ -587,6 +587,12 @@ layout: default
   time you need that please immediately undefine `basename()`, and add a
   comment about it, so that no code ever ends up using the POSIX version!
 
+- Never use FILENAME_MAX. Use PATH_MAX instead (for checking maximum size of
+  paths) and NAME_MAX (for checking maximum size of filenames). FILENAME_MAX is
+  not POSIX, and is a confusingly named alias for PATH_MAX on Linux. Note the
+  NAME_MAX does not include space for a trailing NUL, but PATH_MAX does. UNIX
+  FTW!
+
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