Update to handle new version ld.so.hints and info in executable for

configurable fallback search paths, as well as new crt interface version.

Also:
 - even faster getenv(), get all environment variable settings in a single
   pass.
 - ldd printf-like format specifications
 - minor code cleanups, one vsprintf -> vsnprintf (harmless)

The library search sequence is a little more complete now. Before,
it'd search $LD_LIBRARY_PATH (by opendir/readdir/closedir), then read
the hints file, then read /usr/lib (again by scanning thr directory).  It
would then fail if there was no "found" library.

Now, it does LD_LIBRARY_PATH and the hints file the same, but then uses
a longer fallback path.  The -R path is fetched from the executable if
specified at build time, the ldconfig path is appended, and /usr/lib is
appended to that. Duplicates are suppressed.  This means that simply
placing a new library in /usr/local/lib will work (the same as it did in
/usr/lib) without needing ldconfig -m.  It will find it quicker if the
ldconfig is run though.

Similar changes have been made to the NetBSD ld.so, but ours is rather
different now due to John Polstra's speedups and fixes from a while back.

The ldd printf-like format support came direct from NetBSD.

Reviewed by: nate, jdp

4 files changed, 331 insertions, 62 deletions

diff --git a/libexec/rtld-aout/Makefile b/libexec/rtld-aout/Makefile
index 414e18c..d84a0fa 100644
--- a/libexec/rtld-aout/Makefile
+++ b/libexec/rtld-aout/Makefile
@@ -1,10 +1,11 @@
-#	$Id: Makefile,v 1.19 1996/05/07 23:15:58 wosch Exp $
+#	$Id: Makefile,v 1.20 1996/09/12 03:42:54 bde Exp $
 
 PROG=	ld.so
-SRCS=	mdprologue.S rtld.c malloc.c shlib.c etc.c md.c
+SRCS=	mdprologue.S rtld.c malloc.c shlib.c md.c support.c sbrk.c
 MAN1=	rtld.1
 LDDIR?= $(.CURDIR)/..
-PICFLAG=-fpic
+# As there is relocation going on behind GCC's back, don't cache function addresses.
+PICFLAG=-fpic -fno-function-cse
 CFLAGS+=-I$(LDDIR) -I$(.CURDIR) -I$(LDDIR)/$(MACHINE) $(PICFLAG) -DRTLD
 LDFLAGS+=-Bshareable -Bsymbolic -assert nosymbolic
 ASFLAGS+=-k
@@ -16,7 +17,12 @@ MLINKS= rtld.1 ld.so.1
 
 .PATH: $(LDDIR) $(LDDIR)/$(MACHINE)
 
-$(PROG): ${OBJS} ${DPADD}
+.if defined(DESTDIR)
+$(PROG):
+	$(LD) -o $(PROG) $(LDFLAGS) -nostdlib -L${DESTDIR}/usr/lib $(OBJS) $(LDADD)
+.else
+$(PROG):
 	$(LD) -o $(PROG) $(LDFLAGS) $(OBJS) $(LDADD)
+.endif
 
 .include <bsd.prog.mk>
diff --git a/libexec/rtld-aout/rtld.1 b/libexec/rtld-aout/rtld.1
index 565124f..8f9e3fe 100644
--- a/libexec/rtld-aout/rtld.1
+++ b/libexec/rtld-aout/rtld.1
@@ -1,4 +1,4 @@
-.\"	$Id: rtld.1,v 1.3 1996/04/20 18:29:48 jdp Exp $
+.\"	$Id: rtld.1,v 1.4 1996/09/23 22:22:03 wosch Exp $
 .\"
 .\" Copyright (c) 1995 Paul Kranenburg
 .\" All rights reserved.
@@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
 recognises a number of environment variables that can be used to modify
 its behaviour as follows:
 .Pp
-.Bl -tag -width "LD_TRACE_LOADED_OBJECTS"
+.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
 .It Ev LD_LIBRARY_PATH
 A colon separated list of directories, overriding the default search path
 for shared libraries.
@@ -129,6 +129,54 @@ When set, causes
 .Nm
 to exit after loading the shared objects and printing a summary which includes
 the absolute pathnames of all objects, to standard output.
+.It Ev LD_TRACE_LOADED_OBJECTS_FMT1
+.It Ev LD_TRACE_LOADED_OBJECTS_FMT2
+When set, these variables are interpreted as format strings a la
+.Xr printf 3
+to customize the trace output and are used by
+.Xr ldd 1 's
+.Fl f
+option and allows
+.Xr ldd 1
+to be operated as a filter more conveniently.
+The following conversions can be used:
+.Bl -tag -indent "LD_TRACE_LOADED_OBJECTS_FMT1 " -width "xxxx"
+.It \&%a
+The main program's name
+.Po also known as
+.Dq __progname
+.Pc .
+.It \&%A
+The value of the environment variable
+.Ev LD_TRACE_LOADED_OBJECTS_PROGNAME
+.It \&%o
+The libary name.
+.It \&%m
+The library's major version numer.
+.It \&%n
+The library's minor version numer.
+.It \&%p
+The full pathname as determined by
+.Nm rtld Ns 's
+library search rules.
+.It \&%x
+The library's load address.
+.El
+.Pp
+Additionally,
+.Sy \en
+and
+.Sy \et
+are recognised and have their usual meaning.
+.\" .It Ev LD_NO_INTERN_SEARCH
+.\" When set,
+.\" .Nm
+.\" does not process any internal search paths that were recorded in the
+.\" executable.
+.\" .It Ev LD_NOSTD_PATH
+.\" When set, do not include a set of built-in standard directory paths for
+.\" searching. This might be useful when running on a system with a completely
+.\" non-standard filesystem layout.
 .El
 .Pp
 .Sh FILES
diff --git a/libexec/rtld-aout/rtld.1aout b/libexec/rtld-aout/rtld.1aout
index 565124f..8f9e3fe 100644
--- a/libexec/rtld-aout/rtld.1aout
+++ b/libexec/rtld-aout/rtld.1aout
@@ -1,4 +1,4 @@
-.\"	$Id: rtld.1,v 1.3 1996/04/20 18:29:48 jdp Exp $
+.\"	$Id: rtld.1,v 1.4 1996/09/23 22:22:03 wosch Exp $
 .\"
 .\" Copyright (c) 1995 Paul Kranenburg
 .\" All rights reserved.
@@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
 recognises a number of environment variables that can be used to modify
 its behaviour as follows:
 .Pp
-.Bl -tag -width "LD_TRACE_LOADED_OBJECTS"
+.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
 .It Ev LD_LIBRARY_PATH
 A colon separated list of directories, overriding the default search path
 for shared libraries.
@@ -129,6 +129,54 @@ When set, causes
 .Nm
 to exit after loading the shared objects and printing a summary which includes
 the absolute pathnames of all objects, to standard output.
+.It Ev LD_TRACE_LOADED_OBJECTS_FMT1
+.It Ev LD_TRACE_LOADED_OBJECTS_FMT2
+When set, these variables are interpreted as format strings a la
+.Xr printf 3
+to customize the trace output and are used by
+.Xr ldd 1 's
+.Fl f
+option and allows
+.Xr ldd 1
+to be operated as a filter more conveniently.
+The following conversions can be used:
+.Bl -tag -indent "LD_TRACE_LOADED_OBJECTS_FMT1 " -width "xxxx"
+.It \&%a
+The main program's name
+.Po also known as
+.Dq __progname
+.Pc .
+.It \&%A
+The value of the environment variable
+.Ev LD_TRACE_LOADED_OBJECTS_PROGNAME
+.It \&%o
+The libary name.
+.It \&%m
+The library's major version numer.
+.It \&%n
+The library's minor version numer.
+.It \&%p
+The full pathname as determined by
+.Nm rtld Ns 's
+library search rules.
+.It \&%x
+The library's load address.
+.El
+.Pp
+Additionally,
+.Sy \en
+and
+.Sy \et
+are recognised and have their usual meaning.
+.\" .It Ev LD_NO_INTERN_SEARCH
+.\" When set,
+.\" .Nm
+.\" does not process any internal search paths that were recorded in the
+.\" executable.
+.\" .It Ev LD_NOSTD_PATH
+.\" When set, do not include a set of built-in standard directory paths for
+.\" searching. This might be useful when running on a system with a completely
+.\" non-standard filesystem layout.
 .El
 .Pp
 .Sh FILES
diff --git a/libexec/rtld-aout/rtld.c b/libexec/rtld-aout/rtld.c
index 989f77e..7d0e868 100644
--- a/libexec/rtld-aout/rtld.c
+++ b/libexec/rtld-aout/rtld.c
@@ -27,7 +27,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- *	$Id: rtld.c,v 1.33 1996/04/20 18:29:50 jdp Exp $
+ *	$Id: rtld.c,v 1.34 1996/05/22 06:34:12 jdp Exp $
  */
 
 #include <sys/param.h>
@@ -55,7 +55,12 @@
 #include <varargs.h>
 #endif
 
-#include "ld.h"
+#include <link.h>
+
+#include "md.h"
+#include "shlib.h"
+#include "support.h"
+#include "dynamic.h"
 
 #ifndef MAP_ANON
 #define MAP_ANON	0
@@ -96,7 +101,6 @@ struct somap_private {
 #define RTLD_RTLD	0x02
 #define RTLD_DL		0x04
 #define RTLD_INIT	0x08
-#define RTLD_TRACED	0x10
 	unsigned long	a_text;    /* text size, if known     */
 	unsigned long	a_data;    /* initialized data size   */
 	unsigned long	a_bss;     /* uninitialized data size */
@@ -138,6 +142,10 @@ struct somap_private {
 #define LM_STRINGS(smp)	((char *) \
 	((smp)->som_addr + LM_OFFSET(smp) + LD_STRINGS((smp)->som_dynamic)))
 
+/* Start of search paths */
+#define LM_PATHS(smp)	((char *) \
+	((smp)->som_addr + LM_OFFSET(smp) + LD_PATHS((smp)->som_dynamic)))
+
 /* End of text */
 #define LM_ETEXT(smp)	((char *) \
 	((smp)->som_addr + LM_TXTADDR(smp) + LD_TEXTSZ((smp)->som_dynamic)))
@@ -153,6 +161,10 @@ struct somap_private {
 /* Parent of link map */
 #define LM_PARENT(smp)	(LM_PRIVATE(smp)->spd_parent)
 
+static char		__main_progname[] = "main";
+static char		*main_progname = __main_progname;
+static char		us[] = "/usr/libexec/ld.so";
+
 char			**environ;
 char			*__progname;
 int			errno;
@@ -160,13 +172,13 @@ int			errno;
 static uid_t		uid, euid;
 static gid_t		gid, egid;
 static int		careful;
-static char		__main_progname[] = "main";
-static char		*main_progname = __main_progname;
-static char		us[] = "/usr/libexec/ld.so";
 static int		anon_fd = -1;
+
 static char		*ld_library_path;
 static char		*ld_preload;
-static int		tracing;
+static char		*ld_tracing;
+static char		*ld_suppress_warnings;
+static char		*ld_warn_non_pure_code;
 
 struct so_map		*link_map_head;
 struct so_map		*link_map_tail;
@@ -214,6 +226,10 @@ static struct rt_symbol	*enter_rts __P((char *, long, int, caddr_t,
 static void		generror __P((char *, ...));
 static int		maphints __P((void));
 static void		unmaphints __P((void));
+static void		ld_trace __P((struct so_map *));
+static void		rt_readenv __P((void));
+static int		hinthash __P((char *, int));
+int			rtld __P((int, struct crt_ldso *, struct _dynamic *));
 
 static inline int
 strcmp (register const char *s1, register const char *s2)
@@ -241,10 +257,12 @@ struct _dynamic		*dp;
 	struct so_debug		*ddp;
 	struct so_map		*main_map;
 	struct so_map		*smp;
+	char			*add_paths;
 
 	/* Check version */
 	if (version != CRT_VERSION_BSD_2 &&
 	    version != CRT_VERSION_BSD_3 &&
+	    version != CRT_VERSION_BSD_4 &&
 	    version != CRT_VERSION_SUN)
 		return -1;
 
@@ -269,10 +287,17 @@ struct _dynamic		*dp;
 		++reloc;
 	}
 
-	__progname = "ld.so";
+	if (version >= CRT_VERSION_BSD_4)
+		__progname = crtp->crt_ldso;
 	if (version >= CRT_VERSION_BSD_3)
 		main_progname = crtp->crt_prog;
 
+	/* Fill in some fields in _DYNAMIC or crt structure */
+	if (version >= CRT_VERSION_BSD_4)
+		crtp->crt_ldentry = &ld_entry;		/* crt */
+	else
+		crtp->crt_dp->d_entry = &ld_entry;	/* _DYNAMIC */
+
 	/* Setup out (private) environ variable */
 	environ = crtp->crt_ep;
 
@@ -285,19 +310,9 @@ struct _dynamic		*dp;
 	if (careful) {
 		unsetenv("LD_LIBRARY_PATH");
 		unsetenv("LD_PRELOAD");
-	} else {
-		ld_library_path = getenv("LD_LIBRARY_PATH");
-	        ld_preload = getenv("LD_PRELOAD");
 	}
 
-	tracing = getenv("LD_TRACE_LOADED_OBJECTS") != NULL;
-
-	/*
-	 * Setup the directory search list for findshlib.  We use only
-	 * the standard search path.  Any extra directories from
-	 * LD_LIBRARY_PATH are searched explicitly, in rtfindlib.
-	 */
-	std_search_path();
+	rt_readenv();
 
 	anon_open();
 
@@ -315,9 +330,21 @@ struct _dynamic		*dp;
 	LM_PRIVATE(smp)->spd_refcount++;
 	LM_PRIVATE(smp)->spd_flags |= RTLD_RTLD;
 
-	/* Fill in some fields in main's __DYNAMIC structure */
-	crtp->crt_dp->d_entry = &ld_entry;
-	crtp->crt_dp->d_un.d_sdt->sdt_loaded = link_map_head->som_next;
+	/*
+	 * Setup the executable's run path
+	 */
+	if (version >= CRT_VERSION_BSD_4) {
+		add_paths = LM_PATHS(main_map);
+		if (add_paths)
+			add_search_path(add_paths);
+	}
+
+	/*
+	 * Setup the directory search list for findshlib.  We use only
+	 * the standard search path.  Any extra directories from
+	 * LD_LIBRARY_PATH are searched explicitly, in rtfindlib.
+	 */
+	std_search_path();
 
 	/* Map in LD_PRELOADs before the main program's shared objects so we
 	   can intercept those calls */
@@ -330,8 +357,12 @@ struct _dynamic		*dp;
 	if(map_sods(main_map) == -1)
 		return -1;
 
-	if(tracing)	/* We're done */
+	if(ld_tracing) {	/* We're done */
+		ld_trace(link_map_head);
 		exit(0);
+	}
+
+	crtp->crt_dp->d_un.d_sdt->sdt_loaded = link_map_head->som_next;
 
 	/* Relocate and initialize all mapped objects */
 	if(reloc_and_init(main_map) == -1)		/* Failed */
@@ -368,6 +399,90 @@ struct _dynamic		*dp;
 	return LDSO_VERSION_HAS_DLEXIT;
 }
 
+void
+ld_trace(smp)
+	struct so_map *smp;
+{
+	char	*fmt1, *fmt2, *fmt, *main_local;
+	int	c;
+
+	if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
+		main_local = "";
+
+	if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
+		fmt1 = "\t-l%o.%m => %p (%x)\n";
+
+	if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
+		fmt2 = "\t%o (%x)\n";
+
+	for (; smp; smp = smp->som_next) {
+		struct sod	*sodp;
+		char		*name, *path;
+
+		if ((sodp = smp->som_sod) == NULL)
+			continue;
+
+		name = (char *)sodp->sod_name;
+		if (LM_PARENT(smp))
+			name += (long)LM_LDBASE(LM_PARENT(smp));
+
+		if ((path = smp->som_path) == NULL)
+			path = "not found";
+
+		fmt = sodp->sod_library ? fmt1 : fmt2;
+		while ((c = *fmt++) != '\0') {
+			switch (c) {
+			default:
+				putchar(c);
+				continue;
+			case '\\':
+				switch (c = *fmt) {
+				case '\0':
+					continue;
+				case 'n':
+					putchar('\n');
+					break;
+				case 't':
+					putchar('\t');
+					break;
+				}
+				break;
+			case '%':
+				switch (c = *fmt) {
+				case '\0':
+					continue;
+				case '%':
+				default:
+					putchar(c);
+					break;
+				case 'A':
+					printf("%s", main_local);
+					break;
+				case 'a':
+					printf("%s", main_progname);
+					break;
+				case 'o':
+					printf("%s", name);
+					break;
+				case 'm':
+					printf("%d", sodp->sod_major);
+					break;
+				case 'n':
+					printf("%d", sodp->sod_minor);
+					break;
+				case 'p':
+					printf("%s", path);
+					break;
+				case 'x':
+					printf("%p", smp->som_addr);
+					break;
+				}
+				break;
+			}
+			++fmt;
+		}
+	}
+}
 
 /*
  * Allocate a new link map and return a pointer to it.
@@ -420,7 +535,7 @@ alloc_link_map(path, sodp, parent, addr, dp)
 	}
 
 	smp->som_addr = addr;
-	smp->som_path = strdup(path);
+	smp->som_path = path ? strdup(path) : NULL;
 	smp->som_sod = sodp;
 	smp->som_dynamic = dp;
 	smp->som_spd = (caddr_t)smpp;
@@ -709,7 +824,7 @@ map_sods(parent)
 		if(sodp->sod_library) {
 			path = rtfindlib(name, sodp->sod_major,
 					 sodp->sod_minor);
-			if(path == NULL) {
+			if(path == NULL && !ld_tracing) {
 				generror ("Can't find shared library"
 					  " \"lib%s.so.%d.%d\"", name,
 					  sodp->sod_major, sodp->sod_minor);
@@ -724,23 +839,8 @@ map_sods(parent)
 
 		if(path != NULL)
 			smp = map_object(path, sodp, parent);
-
-		if(tracing &&
-		(smp == NULL || !(LM_PRIVATE(smp)->spd_flags & RTLD_TRACED))) {
-			if(sodp->sod_library)
-				printf("\t-l%s.%d => ", name, sodp->sod_major);
-			else
-				printf("\t%s => ", name);
-
-			if(path == NULL)
-				printf("not found\n");
-			else if(smp == NULL)
-				printf("can't load\n");
-			else {
-				printf("%s (%p)\n", path, smp->som_addr);
-				LM_PRIVATE(smp)->spd_flags |= RTLD_TRACED;
-			}
-		}
+		else if (ld_tracing)
+			(void)alloc_link_map(NULL, sodp, parent, 0, 0);
 
 		if(path != NULL)
 			free(path);
@@ -752,7 +852,7 @@ map_sods(parent)
 			solp->sol_next = NULL;
 			*soltail = solp;
 			soltail = &solp->sol_next;
-		} else if(!tracing)
+		} else if(!ld_tracing)
 			break;
 
 		next = sodp->sod_next;
@@ -937,8 +1037,7 @@ caddr_t			addr;
 	else
 		sym = "";
 
-	if (getenv("LD_SUPPRESS_WARNINGS") == NULL &&
-	    getenv("LD_WARN_NON_PURE_CODE") != NULL)
+	if (!ld_suppress_warnings && ld_warn_non_pure_code)
 		warnx("warning: non pure code in %s at %x (%s)",
 				smp->som_path, r->r_address, sym);
 
@@ -1488,7 +1587,8 @@ maphints __P((void))
 
 	if (read(hfd, &hdr, sizeof hdr) != sizeof hdr ||
 	    HH_BADMAG(hdr) ||
-	    hdr.hh_version != LD_HINTS_VERSION_1) {
+	    (hdr.hh_version != LD_HINTS_VERSION_1 &&
+	     hdr.hh_version != LD_HINTS_VERSION_2)) {
 		close(hfd);
 		hints_bad = 1;
 		return -1;
@@ -1508,6 +1608,9 @@ maphints __P((void))
 	hheader = (struct hints_header *)addr;
 	hbuckets = (struct hints_bucket *)(addr + hheader->hh_hashtab);
 	hstrtab = (char *)(addr + hheader->hh_strtab);
+	/* pluck out the system ldconfig path */
+	if (hheader->hh_version >= LD_HINTS_VERSION_2)
+		add_search_path(hstrtab + hheader->hh_dirlist);
 
 	return 0;
 }
@@ -1630,9 +1733,7 @@ rtfindlib(name, major, minor)
 	if (path == NULL)	/* Search the standard directories */
 		path = findshlib(name, &major, &realminor, 0);
 
-	if (path != NULL &&
-	    realminor < minor &&
-	    getenv("LD_SUPPRESS_WARNINGS") == NULL) {
+	if (path != NULL && realminor < minor && !ld_suppress_warnings) {
 		warnx("warning: %s: minor version %d"
 		      " older than expected %d, using it anyway",
 		      path, realminor, minor);
@@ -1703,6 +1804,10 @@ __dlopen(path, mode)
 	struct so_map	*old_tail = link_map_tail;
 	struct so_map	*smp;
 
+	/*
+	 * path == NULL is handled by map_object()
+	 */
+
 	anon_open();
 
 	/* Map the object, and the objects on which it depends */
@@ -1753,16 +1858,21 @@ __dlsym(fd, sym)
 	void	*fd;
 	char	*sym;
 {
-	struct so_map	*src_map = (struct so_map *)fd;
+	struct so_map	*smp = (struct so_map *)fd, *src_map = NULL;
 	struct nzlist	*np;
 	long		addr;
 
+	/*
+	 * Restrict search to passed map if dlopen()ed.
+	 */
+	if (LM_PRIVATE(smp)->spd_flags & RTLD_DL)
+		src_map = smp;
+
 	np = lookup(sym, &src_map, 1);
-	if (np == NULL) {
-		generror ("Symbol \"%s\" not found", sym);
+	if (np == NULL)
 		return NULL;
-        }
 
+	/* Fixup jmpslot so future calls transfer directly to target */
 	addr = np->nz_value;
 	if (src_map)
 		addr += (long)src_map->som_addr;
@@ -1830,7 +1940,64 @@ char	*fmt;
 	va_start(ap);
 #endif
 
-	vsprintf(buf, fmt, ap);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
 	(void)write(1, buf, strlen(buf));
 	va_end(ap);
 }
+
+/*
+ * rt_readenv() etc.
+ *
+ * Do a sweep over the environment once only, pick up what
+ * looks interesting.
+ *
+ * This is pretty obscure, but is relatively simple.  Simply
+ * look at each environment variable, if it starts with "LD_" then
+ * look closer at it.  If it's in our table, set the variable
+ * listed.  effectively, this is like:
+ *    ld_preload = careful ? NULL : getenv("LD_PRELOAD");
+ * except that the environment is scanned once only to pick up all
+ * known variables, rather than scanned multiple times for each
+ * variable.
+ */
+
+#define L(n, u, v) { n, sizeof(n) - 1, u, v },
+struct env_scan_tab {
+	char	*name;
+	int	len;
+	int	unsafe;
+	char	**value;
+} scan_tab[] = {
+	L("LD_LIBRARY_PATH=",		1, &ld_library_path)
+	L("LD_PRELOAD=",		1, &ld_preload)
+	L("LD_TRACE_LOADED_OBJECTS=",	0, &ld_tracing)
+	L("LD_SUPPRESS_WARNINGS=",	0, &ld_suppress_warnings)
+	L("LD_WARN_NON_PURE_CODE=",	0, &ld_warn_non_pure_code)
+	{ NULL, 0, NULL }
+};
+#undef L
+
+void
+rt_readenv()
+{
+	char **p = environ;
+	char *v;
+	struct env_scan_tab *t;
+
+	/* for each string in the environment... */
+	while ((v = *p++)) {
+
+		/* check for LD_xxx */
+		if (v[0] != 'L' || v[1] != 'D' || v[2] != '_')
+			continue;
+
+		for (t = scan_tab; t->name; t++) {
+			if (careful && t->unsafe)
+				continue;	/* skip for set[ug]id */
+			if (strncmp(t->name, v, t->len) == 0) {
+				*t->value = v + t->len;
+				break;
+			}
+		}
+	}
+}