Make the POSIX::setuid and POSIX::setgid to really call setuid()

and setgid() because they were just changing $< and $( which means
only changing the real uid/gid, as opposed to changing both
real and effective ids.  (The alternative way could have been
in POSIX.pm to change $> and $), too, but making a direct call
to the C API feels cleaner.)  Fixes the bug

Subject: [ID 20000904.005] POSIX::setuid() Doesn't Call setuid()
Message-Id: <200009041609.e84G9iN12155@ifr.inside.zvolve.net>

p4raw-id: //depot/perl@7521

5 files changed, 41 insertions, 25 deletions

diff --git a/ext/POSIX/POSIX.pm b/ext/POSIX/POSIX.pm
index 252e5bbad1..e1e6b28e40 100644
--- a/ext/POSIX/POSIX.pm
+++ b/ext/POSIX/POSIX.pm
@@ -734,16 +734,6 @@ sub setbuf {
     redef "IO::Handle::setbuf()";
 }
 
-sub setgid {
-    usage "setgid(gid)" if @_ != 1;
-    $( = $_[0];
-}
-
-sub setuid {
-    usage "setuid(uid)" if @_ != 1;
-    $< = $_[0];
-}
-
 sub setvbuf {
     redef "IO::Handle::setvbuf()";
 }
diff --git a/ext/POSIX/POSIX.pod b/ext/POSIX/POSIX.pod
index 314147cb2b..e93fb742da 100644
--- a/ext/POSIX/POSIX.pod
+++ b/ext/POSIX/POSIX.pod
@@ -1008,9 +1008,12 @@ see L<perlre>.
 
 =item setgid
 
-Sets the real group identifier for this process.
-Identical to assigning a value to the Perl's builtin C<$)> variable,
-see L<perlvar/$UID>.
+Sets the real group identifier and the effective group identifier for
+this process.  Similar to assigning a value to the Perl's builtin
+C<$)> variable, see L<perlvar/$GID>, except that the latter
+will change only the real user identifier, and that the setgid()
+uses only a single numeric argument, as opposed to a space-separated
+list of numbers.
 
 =item setjmp
 
@@ -1063,9 +1066,10 @@ setting the session identifier of the current process.
 
 =item setuid
 
-Sets the real user identifier for this process.
-Identical to assigning a value to the Perl's builtin C<$E<lt>> variable,
-see L<perlvar/$UID>.
+Sets the real user identifier and the effective user identifier for
+this process.  Similar to assigning a value to the Perl's builtin
+C<$E<lt>> variable, see L<perlvar/$UID>, except that the latter
+will change only the real user identifier.
 
 =item sigaction
 
diff --git a/ext/POSIX/POSIX.xs b/ext/POSIX/POSIX.xs
index a536671afc..c5d169a9f2 100644
--- a/ext/POSIX/POSIX.xs
+++ b/ext/POSIX/POSIX.xs
@@ -65,7 +65,7 @@
 #  include <lib$routines.h> /* prototype for lib$ediv() */
 #  include <starlet.h>      /* prototype for sys$gettim() */
 #  if DECC_VERSION < 50000000
-#    define pid_t int       /* old versions of DECC miss this in types.h */
+#    define Pid_t int       /* old versions of DECC miss this in types.h */
 #  endif
 
 #  undef mkfifo
@@ -117,7 +117,7 @@
 #  define mkfifo(a,b) not_here("mkfifo")
 #  define ttyname(a) (char*)not_here("ttyname")
 #  define sigset_t long
-#  define pid_t long
+#  define Pid_t long
 #  ifdef __BORLANDC__
 #    define tzname _tzname
 #  endif
@@ -3545,20 +3545,20 @@ read(fd, buffer, nbytes)
 
 SysRet
 setpgid(pid, pgid)
-	pid_t		pid
-	pid_t		pgid
+	Pid_t		pid
+	Pid_t		pgid
 
-pid_t
+Pid_t
 setsid()
 
-pid_t
+Pid_t
 tcgetpgrp(fd)
 	int		fd
 
 SysRet
 tcsetpgrp(fd, pgrp_id)
 	int		fd
-	pid_t		pgrp_id
+	Pid_t		pgrp_id
 
 int
 uname()
@@ -3940,6 +3940,14 @@ pathconf(filename, name)
 SysRet
 pause()
 
+SysRet
+setgid(gid)
+	Gid_t		gid
+
+SysRet
+setuid(uid)
+	Uid_t		uid
+
 SysRetLong
 sysconf(name)
 	int		name
@@ -3947,3 +3955,5 @@ sysconf(name)
 char *
 ttyname(fd)
 	int		fd
+
+
diff --git a/ext/POSIX/typemap b/ext/POSIX/typemap
index baf9bfc051..c94df7a4b9 100644
--- a/ext/POSIX/typemap
+++ b/ext/POSIX/typemap
@@ -1,8 +1,10 @@
 Mode_t			T_NV
-pid_t			T_NV
+Pid_t			T_NV
 Uid_t			T_NV
 Time_t			T_NV
 Gid_t			T_NV
+Uid_t			T_NV
+Gid_t			T_NV
 Off_t			T_NV
 Dev_t			T_NV
 NV			T_NV
diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index 83f4d9cd9e..49cdcb273e 100644
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -619,7 +619,8 @@ across fork() calls.  (Mnemonic: same as shells.)
 =item $<
 
 The real uid of this process.  (Mnemonic: it's the uid you came I<from>,
-if you're running setuid.)
+if you're running setuid.)  You can change both the real uid and
+the effective uid at the same time by using POSIX::setuid().
 
 =item $EFFECTIVE_USER_ID
 
@@ -632,6 +633,9 @@ The effective uid of this process.  Example:
     $< = $>;		# set real to effective uid
     ($<,$>) = ($>,$<);	# swap real and effective uid
 
+You can change both the effective uid and the real uid at the same
+time by using POSIX::setuid().
+
 (Mnemonic: it's the uid you went I<to>, if you're running setuid.)
 C<< $< >> and C<< $> >> can be swapped only on machines
 supporting setreuid().
@@ -652,6 +656,9 @@ However, a value assigned to C<$(> must be a single number used to
 set the real gid.  So the value given by C<$(> should I<not> be assigned
 back to C<$(> without being forced numeric, such as by adding zero.
 
+You can change both the real gid and the effective gid at the same
+time by using POSIX::setgid().
+
 (Mnemonic: parentheses are used to I<group> things.  The real gid is the
 group you I<left>, if you're running setgid.)
 
@@ -674,6 +681,9 @@ empty list for setgroups(), just repeat the new effective gid; that is,
 to force an effective gid of 5 and an effectively empty setgroups()
 list, say C< $) = "5 5" >.
 
+You can change both the effective gid and the real gid at the same
+time by using POSIX::setgid() (use only a single numeric argument).
+
 (Mnemonic: parentheses are used to I<group> things.  The effective gid
 is the group that's I<right> for you, if you're running setgid.)