From 7197d069cb82286f9789a8ce987fe5f0f5b6f05d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 10 Jan 2024 12:02:13 +0200
Subject: Add ability to specify alternative sysroot for pkg-config files (GC
 issue #59)

Specifically, the new config.cc.pkgconfig.sysroot variable provides roughly
equivalent functionality to PKG_CONFIG_SYSROOT_DIR in pkg-config. For details
and limitations, see "Rewriting Installed Libraries System Root (sysroot)"
in the manual for details.
---
 libbuild2/cc/init.cxx      | 18 ++++++++++++++--
 libbuild2/cc/pkgconfig.cxx | 51 ++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 65 insertions(+), 4 deletions(-)

(limited to 'libbuild2')

diff --git a/libbuild2/cc/init.cxx b/libbuild2/cc/init.cxx
index d766b30..1bddbb2 100644
--- a/libbuild2/cc/init.cxx
+++ b/libbuild2/cc/init.cxx
@@ -100,13 +100,19 @@ namespace build2
       vp.insert<strings> ("config.cc.loptions");
       vp.insert<strings> ("config.cc.aoptions");
       vp.insert<strings> ("config.cc.libs");
-      vp.insert<string>  ("config.cc.internal.scope");
+
+      vp.insert<string> ("config.cc.internal.scope");
+
+      vp.insert<bool> ("config.cc.reprocess"); // See cc.preprocess below.
+
+      vp.insert<abs_dir_path> ("config.cc.pkgconfig.sysroot");
 
       vp.insert<strings> ("cc.poptions");
       vp.insert<strings> ("cc.coptions");
       vp.insert<strings> ("cc.loptions");
       vp.insert<strings> ("cc.aoptions");
       vp.insert<strings> ("cc.libs");
+
       vp.insert<string>  ("cc.internal.scope");
       vp.insert<strings> ("cc.internal.libs");
 
@@ -177,7 +183,6 @@ namespace build2
 
       // Ability to disable using preprocessed output for compilation.
       //
-      vp.insert<bool> ("config.cc.reprocess");
       vp.insert<bool> ("cc.reprocess");
 
       // Register scope operation callback.
@@ -337,6 +342,15 @@ namespace build2
       if (lookup l = lookup_config (rs, "config.cc.reprocess"))
         rs.assign ("cc.reprocess") = *l;
 
+      // config.cc.pkgconfig.sysroot
+      //
+      // Let's look it up instead of just marking for saving to make sure the
+      // path is valid.
+      //
+      // Note: save omitted.
+      //
+      lookup_config (rs, "config.cc.pkgconfig.sysroot");
+
       // Load the bin.config module.
       //
       if (!cast_false<bool> (rs["bin.config.loaded"]))
diff --git a/libbuild2/cc/pkgconfig.cxx b/libbuild2/cc/pkgconfig.cxx
index b0b9675..ff84dc4 100644
--- a/libbuild2/cc/pkgconfig.cxx
+++ b/libbuild2/cc/pkgconfig.cxx
@@ -316,9 +316,15 @@ namespace build2
 
       assert (!ap.empty () || !sp.empty ());
 
-      // Append -I<dir> or -L<dir> option suppressing duplicates.
+      const scope& rs (*s.root_scope ());
+
+      const dir_path* sysroot (
+        cast_null<abs_dir_path> (rs["config.cc.pkgconfig.sysroot"]));
+
+      // Append -I<dir> or -L<dir> option suppressing duplicates. Also handle
+      // the sysroot rewrite.
       //
-      auto append_dir = [] (strings& ops, string&& o)
+      auto append_dir = [sysroot] (strings& ops, string&& o)
       {
         char c (o[1]);
 
@@ -337,6 +343,47 @@ namespace build2
         //    Note that we do normalize -L paths in the usrd logic later
         //    (but not when setting as *.export.loptions).
 
+        if (sysroot != nullptr)
+        {
+          // Notes:
+          //
+          // - The path might not be absolute (we only rewrite absolute ones).
+          //
+          // - Do this before duplicate suppression since options in ops
+          //   already have the sysroot rewritten.
+          //
+          // - Check if the path already starts with sysroot since some .pc
+          //   files might already be in a good shape (e.g., because they use
+          //   ${pcfiledir} to support relocation properly).
+          //
+          const char* op (o.c_str () + 2);
+          size_t on (o.size () - 2);
+
+          if (path_traits::absolute (op, on))
+          {
+            const string& s (sysroot->string ());
+
+            const char* sp (s.c_str ());
+            size_t sn (s.size ());
+
+            if (!path_traits::sub (op, on, sp, sn)) // Already in sysroot.
+            {
+              // Find the first directory seperator that seperates the root
+              // component from the rest of the path (think /usr/include,
+              // c:\install\include). We need to replace the root component
+              // with sysroot. If there is no separator (say, -Ic:) or the
+              // path after the separator is empty (say, -I/), then we replace
+              // the entire path.
+              //
+              size_t p (path_traits::find_separator (o, 2));
+              if (p == string::npos || p + 1 == o.size ())
+                p = o.size ();
+
+              o.replace (2, p - 2, s);
+            }
+          }
+        }
+
         for (const string& x: ops)
         {
           if (x.size () > 2 && x[0] == '-' && x[1] == c)
-- 
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