From f001583a040d9536074b3ad685bb57718df0f2af Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Wed, 28 Apr 2021 10:43:57 +0200 Subject: Add link to more explanation on PATH_MAX --- hurd/porting/guidelines.mdwn | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hurd/porting/guidelines.mdwn b/hurd/porting/guidelines.mdwn index 5986269e..d132f516 100644 --- a/hurd/porting/guidelines.mdwn +++ b/hurd/porting/guidelines.mdwn @@ -132,6 +132,8 @@ If you get Bad File Descriptor error when trying to read from a file (or accessi +Also see + Every unconditionalized use of `PATH_MAX`, `MAX_PATH` or `MAXPATHLEN` is a POSIX incompatibility. If there is no upper limit on the length of a path (as its the case for GNU), this symbol is not defined in any header file. Instead, you need to either use a different implementation that does not rely on the length of a string or use `sysconf()` to query the length at runtime. If `sysconf()` returns -1, you have to use `realloc()` to allocate the needed memory dynamically. Usually it is thus simpler to just use dynamic allocation. Sometimes the amount is actually known. Else, a geometrically growing loop can be used: for instance, see [Pulseaudio patch](http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=patch-pulse;att=1;bug=522100). Note that in some cases there are GNU extensions that just work fine: when the `__GLIBC__` macro is defined, `getcwd()` calls can be just replaced by `get_current_dir_name()` calls. Note: constants such as `_POSIX_PATH_MAX` are only the minimum required value -- cgit v1.2.3