chpst: remove dependency on prot.h

prot.c provides two functions: prot_gid and prot_uid.

prot_gid is fully unused, and depends on {chk,try}shsgr, both of which must be
run at build-time and require that the user has additional groups. They are not
needed by anything else and their removal gets rid of cross-compilation jank.

prot_uid is used (once) by chpst, but since it is a no-op wrapper around
setuid(), its use can be replaced by a normal call to setuid().

Solves the big questions from void-linux#11

src/Makefile

@@ -170,12 +170,6 @@ byte_diff.o: byte.h byte_diff.c compile
 byte_rchr.o: byte.h byte_rchr.c compile
 	./compile byte_rchr.c
 
-chkshsgr: chkshsgr.o load
-	./load chkshsgr 
-
-chkshsgr.o: chkshsgr.c compile
-	./compile chkshsgr.c
-
 choose: choose.sh warn-auto.sh
 	rm -f choose
 	cat warn-auto.sh choose.sh \
@@ -232,11 +226,6 @@ hassgact.h: choose compile hassgact.h1 hassgact.h2 load trysgact.c
 hassgprm.h: choose compile hassgprm.h1 hassgprm.h2 load trysgprm.c
 	./choose cl trysgprm hassgprm.h1 hassgprm.h2 > hassgprm.h
 
-hasshsgr.h: chkshsgr choose compile hasshsgr.h1 hasshsgr.h2 load \
-tryshsgr.c warn-shsgr
-	./chkshsgr || ( cat warn-shsgr; exit 1 )
-	./choose clr tryshsgr hasshsgr.h1 hasshsgr.h2 > hasshsgr.h
-
 haswaitp.h: choose compile haswaitp.h1 haswaitp.h2 load trywaitp.c
 	./choose cl trywaitp haswaitp.h1 haswaitp.h2 > haswaitp.h
 
@@ -292,9 +281,6 @@ pathexec_run.o: compile env.h error.h gen_alloc.h pathexec.h \
 pathexec_run.c str.h stralloc.h
 	./compile pathexec_run.c
 
-prot.o: compile hasshsgr.h prot.c prot.h
-	./compile prot.c
-
 readclose.o: compile error.h gen_alloc.h readclose.c readclose.h \
 stralloc.h
 	./compile readclose.c
@@ -372,7 +358,7 @@ subgetopt.o: compile subgetopt.c subgetopt.h
 	./compile subgetopt.c
 
 sysdeps: compile direntry.h hasflock.h hasmkffo.h hassgact.h \
-hassgprm.h hasshsgr.h haswaitp.h iopause.h load select.h systype \
+hassgprm.h haswaitp.h iopause.h load select.h systype \
 uint64.h reboot_system.h uw_tmp.h socket.lib
 	rm -f sysdeps
 	cat systype compile load socket.lib >>sysdeps
@@ -385,7 +371,6 @@ uint64.h reboot_system.h uw_tmp.h socket.lib
 	grep sysdep iopause.h >>sysdeps
 	grep sysdep hasmkffo.h >>sysdeps
 	grep sysdep hasflock.h >>sysdeps
-	grep sysdep hasshsgr.h >>sysdeps
 	grep sysdep reboot_system.h >>sysdeps
 	grep sysdep uw_tmp.h >>sysdeps
 	cat sysdeps
@@ -444,7 +429,7 @@ buffer_get.o buffer_put.o buffer_read.o buffer_write.o coe.o env.o \
 error.o error_str.o fd_copy.o fd_move.o fifo.o lock_ex.o lock_exnb.o \
 makelib ndelay_off.o ndelay_on.o open_append.o open_read.o \
 open_trunc.o open_write.o openreadclose.o pathexec_env.o \
-pathexec_run.o prot.o readclose.o seek_set.o sgetopt.o sig.o \
+pathexec_run.o readclose.o seek_set.o sgetopt.o sig.o \
 sig_block.o sig_catch.o sig_pause.o stralloc_cat.o stralloc_catb.o \
 stralloc_cats.o stralloc_eady.o stralloc_opyb.o stralloc_opys.o \
 stralloc_pend.o strerr_die.o strerr_sys.o subgetopt.o wait_nohang.o \
@@ -454,7 +439,7 @@ wait_pid.o
 	coe.o env.o error.o error_str.o fd_copy.o fd_move.o fifo.o lock_ex.o \
 	lock_exnb.o ndelay_off.o ndelay_on.o open_append.o open_read.o \
 	open_trunc.o open_write.o openreadclose.o pathexec_env.o \
-	pathexec_run.o prot.o readclose.o seek_set.o sgetopt.o sig.o \
+	pathexec_run.o readclose.o seek_set.o sgetopt.o sig.o \
 	sig_block.o sig_catch.o sig_pause.o stralloc_cat.o stralloc_catb.o \
 	stralloc_cats.o stralloc_eady.o stralloc_opyb.o stralloc_opys.o \
 	stralloc_pend.o strerr_die.o strerr_sys.o subgetopt.o wait_nohang.o \
@@ -465,4 +450,3 @@ wait_nohang.o: compile haswaitp.h wait_nohang.c
 
 wait_pid.o: compile error.h haswaitp.h wait_pid.c
 	./compile wait_pid.c
-

src/TARGETS

@@ -49,8 +49,6 @@ byte_copy.o
 byte_cr.o
 byte_diff.o
 byte_rchr.o
-chkshsgr
-chkshsgr.o
 choose
 coe.o
 compile
@@ -68,7 +66,6 @@ hasflock.h
 hasmkffo.h
 hassgact.h
 hassgprm.h
-hasshsgr.h
 haswaitp.h
 iopause.h
 iopause.o
@@ -85,7 +82,6 @@ open_write.o
 openreadclose.o
 pathexec_env.o
 pathexec_run.o
-prot.o
 readclose.o
 scan_ulong.o
 seek_set.o

src/chpst.c

@@ -8,7 +8,6 @@
 #include "strerr.h"
 #include "str.h"
 #include "uidgid.h"
-#include "prot.h"
 #include "strerr.h"
 #include "scan.h"
 #include "fmt.h"
@@ -80,7 +79,7 @@ void suidgid(char *user, unsigned int ext) {
     }
   if (setgroups(ugid.gids, ugid.gid) == -1) fatal("unable to setgroups");
   if (setgid(*ugid.gid) == -1) fatal("unable to setgid");
-  if (prot_uid(ugid.uid) == -1) fatal("unable to setuid");
+  if (setuid(ugid.uid) == -1) fatal("unable to setuid");
 }
 
 void euidgid(char *user, unsigned int ext) {