Adding support for uid and gid manipulation.

* configure: Added check for geteuid and related functions.

* sysif.c (getuid_wrap, geteuid_wrap, getgid_wrap, getegid_wrap,
getgroups_wrap, setuid_wrap, seteuid_wrap, setgid_wrap, setegid_wrap):
New static functions.
(sysif_init): Register intrinsics getuid, geteuid, getgid,
getegid, getgroups, setuid, seteuid, setgid, setegid.

* txr.1: Documented new functions.

1 files changed, 29 insertions, 0 deletions

diff --git a/configure b/configure
index ccd4b927..56d6b59d 100755
--- a/configure
+++ b/configure
@@ -2019,6 +2019,35 @@ else
   printf "no\n"
 fi
 
+printf "Checking for POSIX geteuid function family ... "
+
+cat > conftest.c <<!
+#include <sys/types.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+  uid_t u = getuid();
+  uid_t e = geteuid();
+  gid_t g = getgid();
+  gid_t h = getegid();
+  setuid(u);
+  seteuid(e);
+  setgid(g);
+  setegid(h);
+  getgroups(0, NULL);
+  return 0;
+}
+!
+
+if conftest ; then
+  printf "yes\n"
+  printf "#define HAVE_GETEUID 1\n" >> $config_h
+  have_unistd=y
+else
+  printf "no\n"
+fi
+
 #
 # Dependent variables
 #