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| -rw-r--r-- | hurd/porting/guidelines.mdwn | 2 |
1 files changed, 2 insertions, 0 deletions
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 <http://pubs.opengroup.org/onlinepubs/009695399/basedefs/limits.h.html> +Also see <https://eklitzke.org/path-max-is-tricky> + 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 |