win32: interpret absolute paths as relative to %SYSTEMDRIVE%

BusyBox contains hardcoded references to absolute paths which
are unique in the *nix world but on Microsoft Windows are
interpreted as being on the current drive.  To make these unique
again consider them to be relative to %SYSTEMDRIVE%.

Support this by adding functions to:

- determine the system drive (not using the environment variable);
- change a process's current directory to the root of the system drive;
- make relative paths absolute before changing directory (if needed).

The following applications have been modified:

- ash references /etc/profile from the system drive;
- dpkg places its data store on and installs files to the system drive;
- rpm installs files to the system drive;
- man looks for configuration files and man pages on the system drive.

See GitHub issue #158.

1 files changed, 13 insertions, 0 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 34ddc14f1..40965bafa 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -14906,6 +14906,9 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
         struct jmploc jmploc;
         struct stackmark smark;
         int login_sh;
+#if ENABLE_PLATFORM_MINGW32
+        char *sd;
+#endif
 
         /* Initialize global data */
         INIT_G_misc();
@@ -15014,6 +15017,16 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
 #endif
 
                 state = 1;
+#if ENABLE_PLATFORM_MINGW32
+                sd = get_system_drive();
+                if (sd) {
+                        char *path = xasprintf("%s/etc/profile", sd);
+                        read_profile(path);
+                        free(sd);
+                        free(path);
+                }
+                else
+#endif
                 read_profile("/etc/profile");
  state1:
                 state = 2;