spawnveg (libast): remove vfork support (re: b810e2d)

spawnveg(3) too engaged in undefined behaviour according to POSIX
if its vfork fallback version was compiled in. It may have worked
well enough on most systems at the time it was written, but no one
has time to keep verifying that. Plus, all modern systems now have
posix_spawn(3), which is the preferred option for spawnveg. So for
us, this is another opportunity for code cleanup.

This commit does not affect ksh's ability to work on old systems,
it's only that running external commands might now be slightly
slower (and quite possibly more reliable) on old systems without
posix_spawn as they will now use the standard fork(2).

src/cmd/ksh93/Mamfile

@@ -1006,8 +1006,6 @@ make install
 				make sh/path.c
 					prev FEATURE/time implicit
 					prev ${PACKAGE_ast_INCLUDE}/endian.h implicit
-					make ${PACKAGE_ast_INCLUDE}/ast_vfork.h implicit
-					done ${PACKAGE_ast_INCLUDE}/ast_vfork.h dontcare
 					make exec_attr.h implicit
 					done exec_attr.h dontcare virtual
 					prev FEATURE/dynamic implicit
@@ -1117,7 +1115,6 @@ make install
 			done waitevent.o generated
 			make xec.o
 				make sh/xec.c
-					prev ${PACKAGE_ast_INCLUDE}/ast_vfork.h implicit
 					prev ${PACKAGE_ast_INCLUDE}/vmalloc.h implicit
 					prev include/streval.h implicit
 					prev FEATURE/locale implicit

src/cmd/ksh93/tests/path.sh

@@ -738,7 +738,7 @@ PATH=$savePATH
 # POSIX: If a command is found but isn't executable, the exit status should be 126.
 # The tests are arranged as follows:
 #   Test *A runs commands with the -c execve(2) optimization.
-#   Test *B runs commands with spawnveg (i.e., with posix_spawn(3) or vfork(2)).
+#   Test *B runs commands with spawnveg (i.e., with posix_spawn(3) where available).
 #   Test *C runs commands with fork(2) in an interactive shell.
 #   Test *D runs commands with 'command -x'.
 #   Test *E runs commands with 'exec'.

src/lib/libast/Mamfile

@@ -1463,8 +1463,6 @@ make install
 					prev port/lclib.h implicit
 					make sfio/sfhdr.h implicit
 						prev port/lclib.h implicit
-						make vfork.h implicit
-						done vfork.h dontcare virtual
 						make stropts.h implicit
 						done stropts.h dontcare virtual
 						prev std/wchar.h implicit
@@ -2706,14 +2704,6 @@ make install
 			done execvpe.o generated
 			make spawnveg.o
 				make comp/spawnveg.c
-					make ast_vfork.h implicit
-						make FEATURE/vfork
-							make features/vfork
-							done features/vfork
-							exec - iffe ${IFFEFLAGS} -v -X ast -X std -c "${CC} ${mam_cc_FLAGS} ${CCFLAGS} ${LDFLAGS}" run features/vfork
-						done FEATURE/vfork generated
-						exec - cmp -s FEATURE/vfork ast_vfork.h || { rm -f ast_vfork.h; ${STDCP} FEATURE/vfork ast_vfork.h; }
-					done ast_vfork.h dontcare generated
 					prev ast_tty.h implicit
 					prev sig.h implicit
 					make process.h implicit
@@ -2725,14 +2715,6 @@ make install
 				prev comp/spawnveg.c
 				exec - ${CC} ${mam_cc_FLAGS} ${CCFLAGS} ${-debug-symbols?1?${mam_cc_DEBUG} -D_BLD_DEBUG?${CCFLAGS.FORCE}?} -I. -Icomp -Iinclude -Istd -c comp/spawnveg.c
 			done spawnveg.o generated
-			make vfork.o
-				make comp/vfork.c
-					prev include/error.h implicit
-					prev include/ast.h implicit
-				done comp/vfork.c
-				prev comp/vfork.c
-				exec - ${CC} ${mam_cc_FLAGS} ${CCFLAGS} -I. -Icomp -Iinclude -Istd -c comp/vfork.c
-			done vfork.o generated
 			make killpg.o
 				make comp/killpg.c
 					prev sig.h implicit
@@ -5094,7 +5076,7 @@ make install
 			exec - ${AR} rc libast.a state.o opendir.o readdir.o rewinddir.o seekdir.o telldir.o getcwd.o fastfind.o hashalloc.o hashdump.o hashfree.o hashlast.o hashlook.o hashscan.o hashsize.o hashview.o hashwalk.o memhash.o memsum.o strhash.o strkey.o strsum.o stracmp.o strnacmp.o ccmap.o ccmapid.o ccnative.o chresc.o chrtoi.o
 			exec - ${AR} rc libast.a streval.o strexpr.o strmatch.o strcopy.o modei.o modex.o strmode.o strlcat.o strlcpy.o strlook.o strncopy.o strsearch.o strpsearch.o stresc.o stropt.o strtape.o strpcmp.o strnpcmp.o strvcmp.o strnvcmp.o tok.o tokline.o tokscan.o pathaccess.o pathcat.o pathcanon.o pathcheck.o pathpath.o pathexists.o pathfind.o pathicase.o pathkey.o pathprobe.o pathrepl.o pathnative.o pathposix.o pathtemp.o pathtmp.o pathstat.o pathgetlink.o pathsetlink.o pathbin.o pathshell.o pathcd.o pathprog.o ftwalk.o ftwflags.o fts.o astintercept.o conformance.o getenv.o setenviron.o optget.o optjoin.o optesc.o optctx.o strsort.o struniq.o magic.o mime.o mimetype.o signal.o sigflag.o systrace.o error.o errorf.o errormsg.o errorx.o localeconv.o setlocale.o translate.o catopen.o iconv.o lc.o lctab.o mc.o base64.o recfmt.o recstr.o reclen.o fmtrec.o fmtbase.o fmtbuf.o fmtclock.o fmtdev.o fmtelapsed.o fmterror.o fmtesc.o fmtfmt.o fmtfs.o fmtident.o fmtint.o fmtip4.o fmtip6.o fmtls.o fmtmatch.o fmtmode.o fmtnum.o fmtperm.o fmtre.o fmttime.o
 			exec - ${AR} rc libast.a fmtuid.o fmtgid.o fmtsignal.o fmtscale.o fmttmx.o fmttv.o fmtversion.o strelapsed.o strperm.o struid.o strgid.o strtoip4.o strtoip6.o stack.o stk.o swapget.o swapmem.o swapop.o swapput.o sigdata.o sigcrit.o sigunblock.o procopen.o procclose.o procrun.o procfree.o tmdate.o tmequiv.o tmfix.o tmfmt.o tmform.o tmgoff.o tminit.o tmleap.o tmlex.o tmlocale.o tmmake.o tmpoff.o tmscan.o tmsleep.o tmtime.o tmtype.o tmweek.o tmword.o tmzone.o tmxdate.o tmxduration.o tmxfmt.o tmxgettime.o tmxleap.o tmxmake.o tmxscan.o tmxsettime.o tmxsleep.o tmxtime.o tmxtouch.o tvcmp.o tvgettime.o tvsettime.o tvsleep.o tvtouch.o cmdarg.o vecargs.o vecfile.o vecfree.o vecload.o vecstring.o univdata.o touch.o mnt.o debug.o memccpy.o memchr.o memcmp.o memcpy.o memdup.o memmove.o memset.o mkdir.o mkfifo.o mknod.o rmdir.o remove.o rename.o link.o unlink.o strdup.o strchr.o strrchr.o strstr.o strtod.o strtold.o strtol.o strtoll.o strtoul.o strtoull.o strton.o strtonll.o strntod.o strntold.o strnton.o
-			exec - ${AR} rc libast.a strntonll.o strntol.o strntoll.o strntoul.o strntoull.o strcasecmp.o strncasecmp.o strerror.o mktemp.o tmpnam.o fsync.o execlp.o execve.o execvp.o execvpe.o spawnveg.o vfork.o killpg.o getlogin.o putenv.o setenv.o unsetenv.o lstat.o statvfs.o eaccess.o gross.o omitted.o readlink.o symlink.o getpgrp.o setpgid.o setsid.o fcntl.o open.o atexit.o getdents.o getwd.o dup2.o errno.o getgroups.o mount.o system.o iblocks.o modedata.o tmdata.o memfatal.o sfkeyprintf.o sfdcdio.o sfdcdos.o sfdcfilter.o sfdcseekable.o sfdcslow.o sfdcsubstr.o sfdctee.o sfdcunion.o sfdcmore.o sfdcprefix.o wc.o wc2utf8.o basename.o closelog.o dirname.o fmtmsglib.o fnmatch.o ftw.o getdate.o getsubopt.o glob.o nftw.o openlog.o re_comp.o resolvepath.o realpath.o regcmp.o regexp.o setlogmask.o strftime.o strptime.o swab.o syslog.o tempnam.o wordexp.o mktime.o regalloc.o regclass.o regcoll.o regcomp.o regcache.o regdecomp.o regerror.o regexec.o regfatal.o reginit.o
+			exec - ${AR} rc libast.a strntonll.o strntol.o strntoll.o strntoul.o strntoull.o strcasecmp.o strncasecmp.o strerror.o mktemp.o tmpnam.o fsync.o execlp.o execve.o execvp.o execvpe.o spawnveg.o killpg.o getlogin.o putenv.o setenv.o unsetenv.o lstat.o statvfs.o eaccess.o gross.o omitted.o readlink.o symlink.o getpgrp.o setpgid.o setsid.o fcntl.o open.o atexit.o getdents.o getwd.o dup2.o errno.o getgroups.o mount.o system.o iblocks.o modedata.o tmdata.o memfatal.o sfkeyprintf.o sfdcdio.o sfdcdos.o sfdcfilter.o sfdcseekable.o sfdcslow.o sfdcsubstr.o sfdctee.o sfdcunion.o sfdcmore.o sfdcprefix.o wc.o wc2utf8.o basename.o closelog.o dirname.o fmtmsglib.o fnmatch.o ftw.o getdate.o getsubopt.o glob.o nftw.o openlog.o re_comp.o resolvepath.o realpath.o regcmp.o regexp.o setlogmask.o strftime.o strptime.o swab.o syslog.o tempnam.o wordexp.o mktime.o regalloc.o regclass.o regcoll.o regcomp.o regcache.o regdecomp.o regerror.o regexec.o regfatal.o reginit.o
 			exec - ${AR} rc libast.a regnexec.o regsubcomp.o regsubexec.o regsub.o regrecord.o regrexec.o regstat.o dtclose.o dtdisc.o dthash.o dtlist.o dtmethod.o dtopen.o dtstat.o dtstrhash.o dttree.o dtuser.o dtview.o dtwalk.o dtnew.o dtcomp.o sfclose.o sfclrlock.o sfdisc.o sfdlen.o sfexcept.o sfgetl.o sfgetu.o sfcvt.o sfecvt.o sffcvt.o sfextern.o sffilbuf.o sfflsbuf.o sfprints.o sfgetd.o sfgetr.o sfllen.o sfmode.o sfmove.o sfnew.o sfpkrd.o sfnotify.o sfnputc.o sfopen.o sfpeek.o sfpoll.o sfpool.o sfpopen.o sfprintf.o sfputd.o sfputl.o sfputr.o sfputu.o sfrd.o sfread.o sfreserve.o sfscanf.o sfseek.o sfset.o sfsetbuf.o sfsetfd.o sfsize.o sfsk.o sfstack.o sfstrtod.o sfsync.o sfswap.o sftable.o sftell.o sftmp.o sfungetc.o sfvprintf.o sfvscanf.o sfwr.o sfwrite.o sfpurge.o sfraise.o sfwalk.o sfgetm.o sfputm.o sfresize.o _sfclrerr.o _sfeof.o _sferror.o _sffileno.o _sfopen.o _sfstacked.o _sfvalue.o _sfgetc.o _sfgetl.o _sfgetl2.o _sfgetu.o _sfgetu2.o _sfdlen.o _sfllen.o _sfslen.o _sfulen.o _sfputc.o _sfputd.o _sfputl.o _sfputm.o
 			exec - ${AR} rc libast.a _sfputu.o clearerr.o fclose.o fdopen.o fflush.o fgetc.o fgetpos.o fgets.o fopen.o fprintf.o fpurge.o fputs.o fread.o freopen.o fscanf.o fseek.o fseeko.o fsetpos.o ftell.o ftello.o fwrite.o getw.o pclose.o popen.o printf.o putchar.o puts.o putw.o rewind.o scanf.o setbuf.o setbuffer.o setlinebuf.o setvbuf.o snprintf.o sprintf.o sscanf.o asprintf.o vasprintf.o tmpfile.o ungetc.o vfprintf.o vfscanf.o vprintf.o vscanf.o vsnprintf.o vsprintf.o vsscanf.o _doprnt.o _doscan.o _filbuf.o _flsbuf.o _stdopen.o _stdprintf.o _stdscanf.o _stdsprnt.o _stdvbuf.o _stdvsnprnt.o _stdvsprnt.o _stdvsscn.o fgetwc.o fwprintf.o putwchar.o vfwscanf.o wprintf.o fgetws.o fwscanf.o swprintf.o vswprintf.o wscanf.o fputwc.o getwc.o swscanf.o vswscanf.o fputws.o getwchar.o ungetwc.o vwprintf.o fwide.o putwc.o vfwprintf.o vwscanf.o stdio_c99.o fcloseall.o fmemopen.o getdelim.o getline.o frexp.o frexpl.o astcopy.o
 			exec - ${AR} rc libast.a astconf.o astdynamic.o astquery.o astwinsize.o conftab.o aststatic.o getopt.o getoptl.o aso.o asolock.o asometh.o asorelax.o aso-sem.o aso-fcntl.o vmbest.o vmclear.o vmclose.o vmdcheap.o vmdebug.o vmdisc.o vmlast.o vmopen.o vmpool.o vmprivate.o vmprofile.o vmregion.o vmsegment.o vmset.o vmstat.o vmstrdup.o vmtrace.o vmwalk.o vmmopen.o malloc.o vmgetmem.o
@@ -5961,12 +5943,6 @@ make install
 		exec - then ${STDCP} ast_tty.h ${INSTALLROOT}/include/ast/ast_tty.h
 		exec - fi
 	done ${INSTALLROOT}/include/ast/ast_tty.h generated
-	make ${INSTALLROOT}/include/ast/ast_vfork.h
-		prev ast_vfork.h
-		exec - if ! cmp -s ast_vfork.h ${INSTALLROOT}/include/ast/ast_vfork.h
-		exec - then ${STDCP} ast_vfork.h ${INSTALLROOT}/include/ast/ast_vfork.h
-		exec - fi
-	done ${INSTALLROOT}/include/ast/ast_vfork.h generated
 	make ${INSTALLROOT}/include/ast/ast_wait.h
 		prev ast_wait.h
 		exec - if ! cmp -s ast_wait.h ${INSTALLROOT}/include/ast/ast_wait.h

src/lib/libast/comp/spawnveg.c

@@ -153,7 +153,6 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 #include <wait.h>
 #include <sig.h>
 #include <ast_tty.h>
-#include <ast_vfork.h>
 
 #if _lib_spawnve && _hdr_process
 #include <process.h>
@@ -162,10 +161,6 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 #endif
 #endif
 
-#if !_lib_vfork
-#undef	_real_vfork
-#endif
-
 /*
  * fork+exec+(setsid|setpgid)
  */
@@ -177,12 +172,7 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 	int			m;
 	pid_t			pid;
 	pid_t			rid;
-#if _real_vfork
-	volatile int		exec_errno;
-	volatile int* volatile	exec_errno_ptr;
-#else
 	int			err[2];
-#endif /* _real_vfork */
 
 	NOT_USED(tcfd);
 	if (!envv)
@@ -192,24 +182,15 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 		return spawnve(path, argv, envv);
 #endif /* _lib_spawnve */
 	n = errno;
-#if _real_vfork
-	exec_errno = 0;
-	exec_errno_ptr = &exec_errno;
-#else
 	if (pipe(err) < 0)
 		err[0] = -1;
 	else
 	{
 		fcntl(err[0], F_SETFD, FD_CLOEXEC);
 		fcntl(err[1], F_SETFD, FD_CLOEXEC);
 	}
-#endif /* _real_vfork */
 	sigcritical(SIG_REG_EXEC|SIG_REG_PROC);
-#if _lib_vfork
-	pid = vfork();
-#else
 	pid = fork();
-#endif /* _lib_vfork */
 	if (pid == -1)
 		n = errno;
 	else if (!pid)
@@ -233,26 +214,14 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 #endif /* _lib_tcgetpgrp */
 		}
 		execve(path, argv, envv);
-#if _real_vfork
-		*exec_errno_ptr = errno;
-#else
 		if (err[0] != -1)
 		{
 			m = errno;
 			write(err[1], &m, sizeof(m));
 		}
-#endif /* _real_vfork */
 		_exit(errno == ENOENT ? EXIT_NOTFOUND : EXIT_NOEXEC);
 	}
 	rid = pid;
-#if _real_vfork
-	if (pid != -1 && (m = *exec_errno_ptr))
-	{
-		while (waitpid(pid, NULL, 0) == -1 && errno == EINTR);
-		rid = pid = -1;
-		n = m;
-	}
-#else
 	if (err[0] != -1)
 	{
 		close(err[1]);
@@ -274,7 +243,6 @@ spawnveg(const char* path, char* const argv[], char* const envv[], pid_t pgid, i
 		}
 		close(err[0]);
 	}
-#endif /* _real_vfork */
 	sigcritical(0);
 	if (pid != -1 && pgid > 0)
 	{

src/lib/libast/features/lib

@@ -3,7 +3,7 @@ ref	-D_def_map_ast=1
 cmd	universe
 
 hdr	dirent,direntry,filio,fmtmsg,fnmatch,jioctl,libgen,limits
-hdr	locale,ndir,nl_types,process,spawn,syslog,utime,vfork
+hdr	locale,ndir,nl_types,process,spawn,syslog,utime
 hdr	linux/fs,linux/msdos_fs,sys/ioctl
 hdr	wctype
 hdr	wchar note{ <wchar.h> and isw*() really work }end execute{
@@ -52,7 +52,7 @@ mem	DIR.dd_fd sys/types.h - dirent.h - sys/dir.h
 mem	inheritance.pgroup spawn.h
 
 sys	dir,filio,jioctl,localedef,ptem,resource
-sys	socket,stream,systeminfo,universe,vfork
+sys	socket,stream,systeminfo,universe
 
 tst	tst_errno note{ errno can be assigned }end link{
 	#define error		______error
@@ -187,49 +187,6 @@ tst	pipe_rw note{ full duplex pipes }end execute{
 	}
 }end
 
-tst	lib_vfork unistd.h stdlib.h vfork.h note{ vfork exists and it works }end execute{
-	#include <signal.h>
-	#include <sys/wait.h>
-	int
-	main(argc, argv)
-	int	argc;
-	char**	argv;
-	{
-		int	status;
-		char*	cmd[3];
-		if (argv[1])
-			_exit(signal(SIGHUP, SIG_DFL) != SIG_IGN);
-		signal(SIGHUP, SIG_IGN);
-		switch (vfork())
-		{
-		case -1:
-			_exit(1);
-		case 0:
-			cmd[0] = argv[0];
-			cmd[1] = "test";
-			cmd[2] = 0;
-			execv(cmd[0], cmd);
-			_exit(2);
-		}
-		status = 1;
-		_exit(wait(&status) < 0 || status != 0);
- 	}
-}end
-
-tst	real_vfork note{ vfork child shares data with parent }end execute{
-	extern int	_exit(int);
-	extern int	vfork(void);
-	int		code;
-	int
-	main()
-	{
-		code = 1;
-		if (!vfork())
-			code = 0;
-		_exit(code);
-	}
-}end
-
 tst	lib_posix_spawn unistd.h stdlib.h spawn.h -Dfork=______fork note{ posix_spawn exists, it works and it's worth using }end status{
 	#include <sys/types.h>
 	#include <sys/stat.h>
@@ -636,7 +593,7 @@ tst	- output{
 	int
 	main()
 	{
-	#if _lib_posix_spawn || _lib_spawn_mode || _lib_spawn && _hdr_spawn && _mem_pgroup_inheritance || _lib_vfork && _real_vfork
+	#if _lib_posix_spawn || _lib_spawn_mode || _lib_spawn && _hdr_spawn && _mem_pgroup_inheritance
 		printf("#if !_AST_no_spawnveg\n");
 		printf("#define _use_spawnveg	1\n");
 		printf("#endif\n");

src/lib/libast/man/compat.3

@@ -80,7 +80,6 @@ long	sysconf(int);
 int	system(const char*);
 char*	tmpnam(char*);
 int	unlink(const char*);
-int	vfork(void);
 int	waitpid(pid_t, int*, int);
 .EE
 .SH DESCRIPTION

src/lib/libast/man/spawnveg.3

@@ -52,11 +52,9 @@ combines
 and
 .IR setsid (2)
 into a single call.
-If one of either
+If
 .IR posix_spawn (3)
-or
-.IR vfork (2)
-is available, those functions are preferred over
+is available, that function is preferred over
 .IR fork .
 .PP
 .LR command ,
@@ -109,4 +107,4 @@ cannot make the new process a session leader when using the
 .I posix_spawn
 API.
 .SH "SEE ALSO"
-fork(2), vfork(2), posix_spawn(3), exec(2), setpgid(2), setsid(2), spawnve(2)
+fork(2), posix_spawn(3), exec(2), setpgid(2), setsid(2), spawnve(2)

src/lib/libast/sfio/sfhdr.h

@@ -138,17 +138,6 @@
 #define X_OK	01
 #endif
 
-/* alternative process forking */
-#if _lib_vfork && !defined(fork) && !defined(__sparc) && !defined(__sparc__)
-#if _hdr_vfork
-#include	<vfork.h>
-#endif
-#if _sys_vfork
-#include	<sys/vfork.h>
-#endif
-#define fork	vfork
-#endif
-
 /* Private flags in the "bits" field */
 #define SF_MMAP		00000001	/* in memory mapping mode		*/
 #define SF_BOTH		00000002	/* both read/write			*/