From a0ac0f1bc48afa19611b72382abf8cc5250442bc Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Thu, 26 Nov 2020 12:05:34 +0100
Subject: [PATCH] WIP LoadPackageKernelExtension,
 IsPackageKernelExtensionAvailable

---
 lib/files.gd   | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/package.gi | 12 +++++++++++
 src/modules.c  | 15 +++++++-------
 3 files changed, 75 insertions(+), 7 deletions(-)

diff --git a/lib/files.gd b/lib/files.gd
index c13f250e3f7..c58b64bc409 100644
--- a/lib/files.gd
+++ b/lib/files.gd
@@ -626,6 +626,61 @@ BIND_GLOBAL( "LoadStaticModule", function( arg )
 end );
 
 
+#############################################################################
+##
+#F  IsPackageKernelExtensionAvailable( <pkgname> [, <modname> ] )
+##
+BIND_GLOBAL( "IsPackageKernelExtensionAvailable", function( pkgname, modname... )
+    local fname;
+
+    if Length(modname) = 0 then
+        modname := pkgname;
+    elif Length(modname) = 1 then
+        modname := modname[1];
+    else
+        Error( "usage: IsPackageKernelExtensionAvailable( <pkgname> [, <modname> ] )" );
+    fi;
+
+    if modname in SHOW_STAT() then
+        return true;
+    fi;
+    fname := Filename(DirectoriesPackagePrograms(pkgname), Concatenation(modname, ".so"));
+    if fname <> fail then
+        # TODO: better error handling?
+        return LOAD_DYN(fname, true);
+    fi;
+    return false;
+end );
+
+
+#############################################################################
+##
+#F  LoadPackageKernelExtension( <pkgname> [, <modname> ] )
+##
+BIND_GLOBAL( "LoadPackageKernelExtension", function( pkgname, modname... )
+    local fname;
+
+    if Length(modname) = 0 then
+        modname := pkgname;
+    elif Length(modname) = 1 then
+        modname := modname[1];
+    else
+        Error( "usage: LoadPackageKernelExtension( <pkgname> [, <modname> ] )" );
+    fi;
+
+    if modname in SHOW_STAT() then
+        LoadStaticModule(modname);
+        return true;
+    fi;
+    fname := Filename(DirectoriesPackagePrograms(pkgname), Concatenation(modname, ".so"));
+    if fname <> fail then
+        LoadDynamicModule(fname);
+        return true;
+    fi;
+    return false;
+end );
+
+
 #############################################################################
 ##
 #F  Edit( <filename> )  . . . . . . . . . . . . . . . . .  edit and read file
diff --git a/lib/package.gi b/lib/package.gi
index 489256f1638..ccfcad050d5 100644
--- a/lib/package.gi
+++ b/lib/package.gi
@@ -1210,6 +1210,18 @@ InstallGlobalFunction( DirectoriesPackagePrograms, function( name )
       # This package is not known.
       return [];
     fi;
+# FIXME: inject another secondary path??? to allow "out of tree builds"
+# for packages, and/or allow GAP itself to store binaries for the package
+# so that the precise combination of GAP and package are matched...
+# That is, take the precise GAP version (possibly including the git commit
+# it was compiled from), plus the package version (and possibly also the locations of both?)
+# and combine them into a unique ID (e.g. via a hash), then use that to
+# store .so binaries
+
+
+# also add a new mechanism to integrate kernel extensions into a package:
+# let the package declare in its PackageInfo.g that it has a kernel extension;
+# how to build it; what's its name; then GAP can take care of that dynamically
     return [ Directory( Concatenation( installationpath, "/bin/",
                             GAPInfo.Architecture, "/" ) ) ];
 end );
diff --git a/src/modules.c b/src/modules.c
index 4896b3a2a48..1cdab369ea4 100644
--- a/src/modules.c
+++ b/src/modules.c
@@ -229,17 +229,14 @@ static Int SyLoadModule(const Char * name, InitInfoFunc * func)
 #endif
 
 
-
 /****************************************************************************
 **
 *F  FuncLOAD_DYN( <self>, <name>, <crc> ) . . .  try to load a dynamic module
 */
-static Obj FuncLOAD_DYN(Obj self, Obj filename, Obj crc)
+static Obj FuncLOAD_DYN(Obj self, Obj filename, Obj justTestAvailability)
 {
     RequireStringRep(SELF_NAME, filename);
-    if (!IS_INTOBJ(crc) && crc != False) {
-        RequireArgument(SELF_NAME, crc, "must be a small integer or 'false'");
-    }
+    RequireTrueOrFalse(SELF_NAME, justTestAvailability);
 
 #if !defined(HAVE_DLOPEN)
     /* no dynamic library support                                          */
@@ -279,6 +276,7 @@ static Obj FuncLOAD_DYN(Obj self, Obj filename, Obj crc)
     if (info->type % 10 > 2)
         ErrorMayQuit("LOAD_DYN: Invalid kernel module", 0, 0);
 
+#if 0
     /* check the crc value                                                 */
     if (crc != False) {
         if (INT_INTOBJ(crc) != info->crc) {
@@ -289,9 +287,12 @@ static Obj FuncLOAD_DYN(Obj self, Obj filename, Obj crc)
             return False;
         }
     }
+#endif
 
-    ActivateModule(info);
-    RecordLoadedModule(info, 0, CONST_CSTR_STRING(filename));
+    if (justTestAvailability != True) {
+        ActivateModule(info);
+        RecordLoadedModule(info, 0, CONST_CSTR_STRING(filename));
+    }
 
     return True;
 #endif