kernel: add SyDefaultRootPath

The main motivation here is to avoid calling `SySetGapRootPath` in
`main` -- instead we want to defer this until just before we parse
the command line arguments specifying root paths. This will in the
future allow us to switch `SySetGapRootPath` to using GAP objects.

Author: fingolfin

src/main.c

@@ -41,7 +41,7 @@ extern int realmain(int argc, const char * argv[]);
 
 static void SetupInitialGapRoot(const char * argv0)
 {
-    SySetGapRootPath(SYS_DEFAULT_PATHS);
+    gap_strlcpy(SyDefaultRootPath, SYS_DEFAULT_PATHS, sizeof(SyDefaultRootPath));
 }
 
 #else
@@ -165,19 +165,14 @@ static void SySetInitialGapRootPaths(const char * GAPExecLocation)
             strxcat(initgbuf, "lib/init.g", sizeof(initgbuf));
 
             if (SyIsReadableFile(initgbuf) == 0) {
-                SySetGapRootPath(pathbuf);
+                gap_strlcpy(SyDefaultRootPath, pathbuf, sizeof(SyDefaultRootPath));
                 // escape from loop
                 return;
             }
             // try up a directory level
             strxcat(pathbuf, "../", sizeof(pathbuf));
         }
     }
-
-    // Set GAP root path to current directory, if we have no other
-    // idea, and for backwards compatibility.
-    // Note that GAPExecLocation must always end with a slash.
-    SySetGapRootPath("./");
 }
 
 static void SetupInitialGapRoot(const char * argv0)

src/sysroots.c

@@ -21,6 +21,16 @@
 #include <stdlib.h>
 
 
+/****************************************************************************
+**
+*V  SyDefaultRootPath
+**
+**  Default initial root path. Default is the current directory, if we have
+**  no other idea, for backwards compatibility.
+*/
+char SyDefaultRootPath[GAP_PATH_MAX] = "./";
+
+
 /****************************************************************************
 **
 *V  SyGapRootPaths  . . . . . . . . . . . . . . . . . . . array of root paths

src/sysroots.h

@@ -13,6 +13,17 @@
 #define GAP_SYSROOTS_H
 
 #include "common.h"
+#include "system.h"
+
+
+/****************************************************************************
+**
+*V  SyDefaultRootPath
+**
+**  Default initial root path. Default is the current directory, if we have
+**  no other idea, for backwards compatibility.
+*/
+extern char SyDefaultRootPath[GAP_PATH_MAX];
 
 #include <stddef.h>
 

src/system.c

@@ -710,6 +710,8 @@ void InitSystem(int argc, const char * argv[], BOOL handleSignals)
 
 void InitRootPaths(int argc, const char * argv[])
 {
+    SySetGapRootPath(SyDefaultRootPath);
+
     // second stage of command line options parsing: handle root paths
     ParseCommandLineOptions(argc, argv, 1);