XDG Base Directory compliance

[kintel]

Split out from #125 as a separate, Unix/Linux-specific issue.

Idea from chrysn:

on linux and other free unices, the paths should follow the fdo basedir spec. for openscad library includes, that means for inclusion of a relative file $x (in pseudo code):

$XDG_DATA_HOME = $XDG_DATA_HOME if defined, otherwise ${HOME}/.local/share
$XDG_DATA_DIRS = $XDG_DATA_DIRS if defined, otherwise /usr/local/share/:/usr/share/
$xdgpaths = $XDG_DATA_HOME:$XDG_DATA_DIRS
$searchpaths = $xdgpaths, and append /openscad/libraries/ to each part separated by ':'
if $OPENSCADPATH is defined
    $searchpaths = $OPENSCADPATH:$searchpaths
for every $part of $searchpaths split by ':'
    if file $part/$x is readable:
        include that file

this also catches the current default paths /usr/share/openscad/libraries or /usr/local/share/openscad/libraries. if other paths can be configured at compile time, they should be appended to $searchpaths. (ie the default paths should stay there to conform to basedir spec).

---

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[Earnestly]

Hopefully this can help get you closer to this goal:

From a4e3054a8a57cfaf21570033c3bad6d24949b45c Mon Sep 17 00:00:00 2001
From: Earnestly <zibeon@gmail.com>
Date: Fri, 29 May 2015 15:15:46 +0100
Subject: [PATCH] Avoid hard-coding HOME/.local/share

Adapt the code from userConfigPath to documentsPath in order to avoid
hard-coding the location.  Use XDG_DATA_HOME instead and fallback
accordingly.

This also cleans up a few cases of trailing whitespace.
---
 src/PlatformUtils-posix.cc | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/src/PlatformUtils-posix.cc b/src/PlatformUtils-posix.cc
index cc45df4..6bdb5c6 100644
--- a/src/PlatformUtils-posix.cc
+++ b/src/PlatformUtils-posix.cc
@@ -19,22 +19,30 @@ std::string PlatformUtils::pathSeparatorChar()

 std::string PlatformUtils::documentsPath()
 {
+    fs::path docpath;
+
+    const char *xdg_env = getenv("XDG_DATA_HOME");
+    if (xdg_env && fs::exists(fs::path(xdg_env))) {
+   docpath = fs::path(xdg_env) / OPENSCAD_FOLDER_NAME;
+    } else {
    const char *home = getenv("HOME");
    if (home) {
-       fs::path docpath(home);
-       docpath = docpath / ".local" / "share";
-       return boosty::stringy(docpath);
-   }
-   else {
-       return "";
+       config_path = fs::path(home) / ".local" / "share" / OPENSCAD_FOLDER_NAME;
    }
+    }
+
+    if (fs::is_directory(config_path)) {
+   return boosty::stringy(boosty::absolute(docpath));
+    }
+
+    return "";
 }

 // see http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
 std::string PlatformUtils::userConfigPath()
 {
     fs::path config_path;
-    
+
     const char *xdg_env = getenv("XDG_CONFIG_HOME");
     if (xdg_env && fs::exists(fs::path(xdg_env))) {
    config_path = fs::path(xdg_env) / OPENSCAD_FOLDER_NAME;
@@ -48,7 +56,7 @@ std::string PlatformUtils::userConfigPath()
     if (fs::is_directory(config_path)) {
    return boosty::stringy(boosty::absolute(config_path));
     }
-    
+
     return "";
 }

@@ -110,7 +118,7 @@ static std::string checkEtcIssue()
     boost::regex esc("\\\\.");
     issue = boost::regex_replace(issue, esc, "");
     boost::algorithm::trim(issue);
-    
+
     return issue;
 }

@@ -125,14 +133,14 @@ static std::string detectDistribution()
     if (!etcissue.empty()) {
    return etcissue;
     }
-    
+
     return "";
 }

 std::string PlatformUtils::sysinfo(bool extended)
 {
     std::string result;
-    
+
     struct utsname osinfo;
     if (uname(&osinfo) == 0) {
            result += osinfo.sysname;
@@ -145,7 +153,7 @@ std::string PlatformUtils::sysinfo(bool extended)
     } else {
            result += "Unknown Linux";
     }
-    
+
     std::string distribution = detectDistribution();
     if (!distribution.empty()) {
            result += " ";
@@ -162,7 +170,7 @@ std::string PlatformUtils::sysinfo(bool extended)
                    result += "s";
                }
            }
-           
+
            long pages = sysconf(_SC_PHYS_PAGES);
            long pagesize = sysconf(_SC_PAGE_SIZE);
            if ((pages > 0) && (pagesize > 0)) {
@@ -171,7 +179,7 @@ std::string PlatformUtils::sysinfo(bool extended)
                result += " RAM";
            }
        }
-       
+
     return result;
 }

-- 
2.4.2