Use dynamic maximum configuration values when necessary (#370)

This commit fixes an issue with how ksh was obtaining the value of
NGROUPS_MAX. On some systems this setting can be changed (e.g., on
illumos adding 'set ngroups_max=32' to /etc/system then rebooting
changes NGROUPS_MAX from 16 to 32). Ksh was using NGROUPS_MAX with
the assumption it's a static value, which could cause issues on
systems where it isn't static. This bugfix is inspired by the one
from <https://github.com/lkujaw/ast/commit/b1362c3a5>, although it
has been expanded a bit to account for OPEN_MAX as well.

src/cmd/ksh93/sh/init.c, src/lib/libcmd/fds.c:
- Rename the getconf() macro to astconf_long() and move it to ast.h
  to prevent redundancy. Other sections of the code have been
  modified to use this macro for astconf() to account for
  dynamic settings.
- An equivalent macro for unsigned long values (astconf_ulong) has
  been added.
- Prefer sysconf(3) where available. It has better performance as it
  returns a numeric value directly instead of via string
  conversion.
- The astconf_long and astconf_ulong macros have been documented in
  the ast(3) man page.

src/cmd/ksh93/bltins/test.c

@@ -666,7 +666,7 @@ skip:
 				if((maxgroups=getgroups(0,(gid_t*)0)) <= 0)
 				{
 					/* pre-POSIX system */
-					maxgroups=NGROUPS_MAX;
+					maxgroups = (int)astconf_long(CONF_NGROUPS_MAX);
 				}
 			}
 			groups = (gid_t*)stakalloc((maxgroups+1)*sizeof(gid_t));

src/cmd/ksh93/features/externs

@@ -46,7 +46,7 @@ tst	note{ determining extra bytes per argument for arguments list }end output{
 			for(i=0; environ[i]; i++)
 				envlen += strlen(environ[i]) + 1 + extra_bytes;
 			envlen += 1 + extra_bytes;	/* final null element */
-			argmax = strtoimax(astconf("ARG_MAX",NiL,NiL),NiL,0) - envlen;
+			argmax = (int)astconf_long(CONF_ARG_MAX) - envlen;
 			if (argmax < 2048)
 			{
 				error(ERROR_ERROR|2, "argmax too small");

src/cmd/ksh93/sh/init.c

@@ -144,9 +144,6 @@ char e_version[]	= "\n@(#)$Id: Version "
     extern char	**environ;
 #endif
 
-#undef	getconf
-#define getconf(x)	strtol(astconf(x,NiL,NiL),NiL,0)
-
 struct seconds
 {
 	Namfun_t	hdr;
@@ -1223,9 +1220,9 @@ Shell_t *sh_init(register int argc,register char *argv[], Shinit_f userinit)
 		shgd->euserid=geteuid();
 		shgd->groupid=getgid();
 		shgd->egroupid=getegid();
-		shgd->lim.clk_tck = getconf("CLK_TCK");
+		shgd->lim.arg_max = astconf_long(CONF_ARG_MAX);
-		shgd->lim.arg_max = getconf("ARG_MAX");
+		shgd->lim.child_max = (int)astconf_long(CONF_CHILD_MAX);
-		shgd->lim.child_max = getconf("CHILD_MAX");
+		shgd->lim.clk_tck = (int)astconf_long(CONF_CLK_TCK);
 		if(shgd->lim.arg_max <=0)
 			shgd->lim.arg_max = ARG_MAX;
 		if(shgd->lim.child_max <=0)

src/cmd/ksh93/sh/io.c

@@ -403,7 +403,7 @@ int  sh_iovalidfd(Shell_t *shp, int fd)
 		return(0);
 	if(fd < shp->gd->lim.open_max)
 		return(1);
-	max = strtol(astconf("OPEN_MAX",NiL,NiL),NiL,0);
+	max = (int)astconf_long(CONF_OPEN_MAX);
 	if(fd >= max)
 	{
 		errno = EBADF;

src/cmd/ksh93/sh/suid_exec.c

@@ -329,7 +329,7 @@ int eaccess(register const char *name, register int mode)
 				if((maxgroups=getgroups(0,groups)) < 0)
 				{
 					/* pre-POSIX system */
-					maxgroups=NGROUPS_MAX;
+					maxgroups = (int)astconf_long(CONF_NGROUPS_MAX);
 				}
 			}
 			groups = (gid_t*)malloc((maxgroups+1)*sizeof(gid_t));

src/lib/libast/comp/eaccess.c

@@ -110,7 +110,7 @@ eaccess(const char* path, register int flags)
 		if (ngroups == -2)
 		{
 			if ((ngroups = getgroups(0, (gid_t*)0)) <= 0)
-				ngroups = NGROUPS_MAX;
+				ngroups = (int)astconf_long(CONF_NGROUPS_MAX);
 			if (!(groups = newof(0, gid_t, ngroups + 1, 0)))
 				ngroups = -1;
 			else

src/lib/libast/include/ast.h

@@ -283,6 +283,27 @@ extern off_t		astcopy(int, int, off_t);
 extern int		astlicense(char*, int, char*, char*, int, int, int);
 extern int		astquery(int, const char*, ...);
 extern void		astwinsize(int, int*, int*);
+#if _lib_sysconf
+/* prefer sysconf for astconf_long and astconf_ulong to improve performance */
+#define CONF_ARG_MAX		_SC_ARG_MAX
+#define CONF_CHILD_MAX		_SC_CHILD_MAX
+#define CONF_CLK_TCK		_SC_CLK_TCK
+#define CONF_NGROUPS_MAX	_SC_NGROUPS_MAX
+#define CONF_OPEN_MAX		_SC_OPEN_MAX
+#define CONF_PAGESIZE		_SC_PAGESIZE
+#define astconf_long(x)		sysconf(x)
+#define astconf_ulong(x)	(unsigned long)sysconf(x)
+#else
+/* fallback in case sysconf isn't available */
+#define CONF_ARG_MAX		"ARG_MAX"
+#define CONF_CHILD_MAX		"CHILD_MAX"
+#define CONF_CLK_TCK		"CLK_TCK"
+#define CONF_NGROUPS_MAX	"NGROUPS_MAX"
+#define CONF_OPEN_MAX		"OPEN_MAX"
+#define CONF_PAGESIZE		"PAGESIZE"
+#define astconf_long(x)		strtol(astconf(x,NiL,NiL),NiL,0)
+#define astconf_ulong(x)	strtoul(astconf(x,NiL,NiL),NiL,0)
+#endif
 
 extern ssize_t		base64encode(const void*, size_t, void**, void*, size_t, void**);
 extern ssize_t		base64decode(const void*, size_t, void**, void*, size_t, void**);

src/lib/libast/man/ast.3

@@ -44,6 +44,8 @@ ast \- miscellaneous libast support
 #include <ast.h>
 
 char*          astconf(const char* \fIname\fP, const char* \fIpath\fP, const char* \fIvalue\fP);
+long           astconf_long(\fIarg\fP);
+unsigned long  astconf_ulong(\fIarg\fP);
 Ast_confdisc_t astconfdisc(Ast_confdisc_t new_notify);
 void           astconflist(Sfio_t* stream, const char* path, int flags);
 off_t          astcopy(int \fIrfd\fP, int \fIwfd\fP, off_t \fIn\fP);
@@ -155,6 +157,30 @@ User defined
 values may also be set and queried, but these should probably have
 some form of vendor prefix to avoid being stomped by future standards.
 .PP
+.L astconf_long
+and
+.L astconf_ulong
+are macros that call either
+.I sysconf
+or
+.LR astconf ,
+preferring
+.I sysconf
+if it's available.
+.L astconf_long
+returns a signed long value while
+.L astconf_ulong
+returns an unsigned long value.
+The argument passed to these macros may be one of the following:
+.EX
+CONF_ARG_MAX
+CONF_CHILD_MAX
+CONF_CLK_TCK
+CONF_NGROUPS_MAX
+CONF_OPEN_MAX
+CONF_PAGESIZE
+.EE
+.PP
 .L astconfdisc
 registers a discipline function
 .EX
@@ -259,7 +285,7 @@ and
 are set to
 .LR 0 .
 If
-.I ioctl (2)
+.IR ioctl (2)
 methods fail then the environment variable
 .L LINES
 is used to set

src/lib/libast/misc/cmdarg.c

@@ -128,7 +128,7 @@ cmdopen_20120411(char** argv, int argmax, int size, const char* argpat, Cmddisc_
 		argc = 0;
 	for (p = environ; *p; p++)
 		n += sizeof(char**) + strlen(*p) + 1;
-	if ((x = strtol(astconf("ARG_MAX", NiL, NiL), NiL, 0)) <= 0)
+	if ((x = astconf_long(CONF_ARG_MAX)) <= 0)
 		x = ARG_MAX;
 	if (size <= 0 || size > x)
 		size = x;

src/lib/libast/path/pathtemp.c

@@ -90,7 +90,7 @@ static inline int xaccess(const char *path, int mode)
 	int ret;
 
 	if (!pgsz)
-		pgsz = strtoul(astconf("PAGESIZE",NiL,NiL),NiL,0);
+		pgsz = astconf_ulong(CONF_PAGESIZE);
 
 	if (!path || !*path)
 	{

src/lib/libast/stdio/vfwscanf.c

@@ -92,7 +92,7 @@ vfwscanf(Sfio_t* f, const wchar_t* fmt, va_list args)
 	n = wcstombs(NiL, fmt, 0);
 	if (w = newof(0, Wide_t, 1, n))
 	{
-		if (t = sfnew(NiL, buf, sizeof(buf), OPEN_MAX+1, SF_READ))
+		if (t = sfnew(NiL, buf, sizeof(buf), (int)astconf_long(CONF_OPEN_MAX)+1, SF_READ))
 		{
 			w->sfdisc.exceptf = wideexcept;
 			w->sfdisc.readf = wideread;

src/lib/libast/string/fmtclock.c

@@ -36,16 +36,16 @@ fmtclock(register Sfulong_t t)
 	char*			buf;
 	int			z;
 
-	static unsigned int	clk_tck;
+	static unsigned long	clk_tck;
 
 	if (!clk_tck)
 	{
 #ifdef CLOCKS_PER_SEC
 		clk_tck = CLOCKS_PER_SEC;
 #else
-		if (!(clk_tck = (unsigned int)strtoul(astconf("CLK_TCK", NiL, NiL), NiL, 10)))
+		if (!(clk_tck = astconf_ulong(CONF_CLK_TCK)))
 			clk_tck = 60;
-#endif
+#endif /* CLOCKS_PER_SEC */
 	}
 	if (t == 0)
 		return "0";

src/lib/libast/vmalloc/malloc.c

@@ -1124,8 +1124,6 @@ char*	ends;
 	return begs;
 }
 
-#define FD_PRIVATE	(3*OPEN_MAX/4)
-
 #if __STD_C
 int _vmfd(int fd)
 #else
@@ -1134,10 +1132,19 @@ int	fd;
 #endif
 {
 	int	pd;
+	int	fd_private = (int)(3 * astconf_long(CONF_OPEN_MAX) / 4);
+	if (fd_private <= 0)
+	{
+#if defined(OPEN_MAX)
+		fd_private = 3 * OPEN_MAX / 4;
+#else
+		fd_private = 3 * FOPEN_MAX / 4;
+#endif
+	}
 
 	if (fd >= 0)
 	{
-		if (fd < FD_PRIVATE && (pd = fcntl(fd, F_DUPFD, FD_PRIVATE)) >= 0)
+		if (fd < fd_private && (pd = fcntl(fd, F_DUPFD, fd_private)) >= 0)
 		{
 			close(fd);
 			fd = pd;

src/lib/libcmd/fds.c

@@ -54,9 +54,6 @@ static const char usage[] =
 #define major(x)	(int)(((unsigned int)(x)>>8)&0xff)
 #endif
 
-#undef	getconf
-#define getconf(x)	strtol(astconf(x,NiL,NiL),NiL,0)
-
 #ifdef S_IFSOCK
 
 typedef struct NV_s
@@ -214,8 +211,14 @@ b_fds(int argc, char** argv, Shbltin_t* context)
 		error(ERROR_usage(2), "%s", optusage(NiL));
 		UNREACHABLE();
 	}
-	if ((open_max = getconf("OPEN_MAX")) <= 0)
+	if ((open_max = (int)astconf_long(CONF_OPEN_MAX)) <= 0)
+	{
+#if defined(OPEN_MAX)
 		open_max = OPEN_MAX;
+#else
+		open_max = FOPEN_MAX;
+#endif
+	}
 	if (unit == 1)
 		sp = sfstdout;
 	else if (fstat(unit, &st) || !(sp = sfnew(NiL, NiL, SF_UNBOUND, unit, SF_WRITE)))

src/lib/libcmd/id.c

@@ -231,7 +231,7 @@ getids(Sfio_t* sp, const char* name, register int flags)
 			 */
 
 			if ((maxgroups = getgroups(0, groups)) <= 0)
-				maxgroups = NGROUPS_MAX;
+				maxgroups = (int)astconf_long(CONF_NGROUPS_MAX);
 			if (!(groups = newof(0, gid_t, maxgroups + 1, 0)))
 			{
 				error(ERROR_SYSTEM|ERROR_PANIC, "out of memory [group array]");