Dynamic object dependency mapping: libmap.

This is an optional feature, disabled by default.

This will be useful to people testing the various POSIX threading
libraries under -CURRENT but can easily serve other needs.

include/paths.h

@@ -60,6 +60,7 @@
 #define	_PATH_ETC	"/etc"
 #define	_PATH_FTPUSERS	"/etc/ftpusers"
 #define	_PATH_KMEM	"/dev/kmem"
+#define	_PATH_LIBMAP_CONF	"/etc/libmap.conf"
 #define	_PATH_LOGIN	"/usr/bin/login"
 #define	_PATH_MAILDIR	"/var/mail"
 #define	_PATH_MAN	"/usr/share/man"

libexec/rtld-elf/Makefile

@@ -10,6 +10,15 @@ INSTALLFLAGS=	-fschg -C -b
 MLINKS=		rtld.1 ld-elf.so.1.1 \
 		rtld.1 ld.so.1
 
+#
+# To enable the libmap.conf functionality please
+# add 'WITH_LIBMAP=yes' to /etc/make.conf, recompile
+# and reinstall rtld-elf.
+.ifdef WITH_LIBMAP
+CFLAGS+=	-DWITH_LIBMAP
+SRCS+=		libmap.c
+.endif
+
 .if exists(${.CURDIR}/${MACHINE_ARCH}/Makefile.inc)
 .include "${.CURDIR}/${MACHINE_ARCH}/Makefile.inc"
 .endif

libexec/rtld-elf/libmap.c

@@ -0,0 +1,199 @@
+/*
+ * $FreeBSD$
+ */
+
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+#include <sys/param.h>
+
+#ifndef _PATH_LIBMAP_CONF
+#define	_PATH_LIBMAP_CONF	"/etc/libmap.conf"
+#endif
+
+TAILQ_HEAD(lm_list, lm);
+struct lm {
+	char *f;
+	char *t;
+
+	TAILQ_ENTRY(lm)	lm_link;
+};
+
+TAILQ_HEAD(lmp_list, lmp) lmp_head = TAILQ_HEAD_INITIALIZER(lmp_head);
+struct lmp {
+	char *p;
+	struct lm_list lml;
+	TAILQ_ENTRY(lmp) lmp_link;
+};
+
+static void		lm_add		(char *, char *, char *);
+static void		lm_free		(struct lm_list *);
+static char *		lml_find	(struct lm_list *, const char *);
+static struct lm_list *	lmp_find	(const char *);
+static struct lm_list *	lmp_init	(char *);
+
+void
+lm_init (void)
+{
+	FILE	*fp;
+	char	*cp;
+	char	*f, *t, *p;
+	char	prog[MAXPATHLEN];
+	char	line[MAXPATHLEN + 2];
+
+	TAILQ_INIT(&lmp_head);
+
+	if ((fp = fopen(_PATH_LIBMAP_CONF, "r")) == NULL)
+		return;
+
+	p = NULL;
+	while ((cp = fgets(line, MAXPATHLEN + 1, fp)) != NULL) {
+		t = f = NULL;
+		/* Skip over leading space */
+		while (!isalpha(*cp) &&
+		       *cp != '#' && *cp != '\0' && *cp != '[') cp++;
+		/* Found a comment or EOL */
+		if (*cp == '#' || *cp == '\0')
+			continue;
+		/* Found a costraint selector */
+		if (*cp == '[') {
+			cp++;
+			/* Skip leading space */
+			while (isspace(*cp) &&
+			       *cp != '#' && *cp != '\0' && *cp != ']') cp++;
+			/* Found comment, EOL or end of selector */
+			if  (*cp == '#' || *cp == '\0' || *cp == ']')
+				continue;
+			p = cp;
+			/* Skip to end of word */
+			while (!isspace(*cp) &&
+			       *cp != '#' && *cp != '\0' && *cp != ']') cp++;
+			*cp++ = '\0';
+			bzero(prog, MAXPATHLEN);
+			strncpy(prog, p, strlen(p));
+			p = prog;
+			continue;
+		}
+		f = cp;
+		while (!isspace(*cp) && *cp != '#' && *cp != '\0') cp++;
+		*cp++ = '\0';
+		while (isspace(*cp) && *cp != '#' && *cp != '\0') cp++;
+		t = cp;
+		while (!isspace(*cp) && *cp != '#' && *cp != '\0') cp++;
+		*cp++ = '\0';
+
+		lm_add(p, strdup(f), strdup(t));
+		bzero(line, sizeof(line));
+	}
+	(void)fclose(fp);
+	return;
+}
+
+static void
+lm_free (struct lm_list *lml)
+{
+	struct lm *lm;
+
+	while (!TAILQ_EMPTY(lml)) {
+		lm = TAILQ_FIRST(lml);
+		TAILQ_REMOVE(lml, lm, lm_link);
+		free(lm->f);
+		free(lm->t);
+		free(lm);
+	}
+	return;
+}
+
+void
+lm_fini (void)
+{
+	struct lmp *lmp;
+
+	while (!TAILQ_EMPTY(&lmp_head)) {
+		lmp = TAILQ_FIRST(&lmp_head);
+		TAILQ_REMOVE(&lmp_head, lmp, lmp_link);
+		free(lmp->p);
+		lm_free(&lmp->lml);
+		free(lmp);
+	}
+	return;
+}
+
+static void
+lm_add (char *p, char *f, char *t)
+{
+	struct lm_list *lml;
+	struct lm *lm;
+
+	if (p == NULL)
+		p = "$DEFAULT$";
+
+#if 0
+	printf("%s(\"%s\", \"%s\", \"%s\")\n", __func__, p, f, t);
+#endif
+
+	if ((lml = lmp_find(p)) == NULL)
+		lml = lmp_init(strdup(p));
+
+	lm = malloc(sizeof(struct lm));
+	lm->f = f;
+	lm->t = t;
+	TAILQ_INSERT_HEAD(lml, lm, lm_link);
+}
+
+char *
+lm_find (const char *p, const char *f)
+{
+	struct lm_list *lml;
+	char *t;
+
+	if (p != NULL && (lml = lmp_find(p)) != NULL) {
+		t = lml_find(lml, f);
+		if (t != NULL)
+			return (t);
+	}
+	lml = lmp_find("$DEFAULT$");
+	if (lml != NULL)
+		return (lml_find(lml, f));
+	else
+		return (NULL);
+}
+
+static char *
+lml_find (struct lm_list *lmh, const char *f)
+{
+	struct lm *lm;
+
+	TAILQ_FOREACH(lm, lmh, lm_link)
+		if ((strncmp(f, lm->f, strlen(lm->f)) == 0) &&
+		    (strlen(f) == strlen(lm->f)))
+			return (lm->t);
+	return NULL;
+}
+
+static struct lm_list *
+lmp_find (const char *n)
+{
+	struct lmp *lmp;
+
+	TAILQ_FOREACH(lmp, &lmp_head, lmp_link)
+		if ((strncmp(n, lmp->p, strlen(lmp->p)) == 0) &&
+		    (strlen(n) == strlen(lmp->p)))
+			return (&lmp->lml);
+	return (NULL);
+}
+
+static struct lm_list *
+lmp_init (char *n)
+{
+	struct lmp *lmp;
+
+	lmp = malloc(sizeof(struct lmp));
+	lmp->p = n;
+	TAILQ_INIT(&lmp->lml);
+	TAILQ_INSERT_HEAD(&lmp_head, lmp, lmp_link);
+
+	return (&lmp->lml);
+}

libexec/rtld-elf/libmap.h

@@ -0,0 +1,7 @@
+/*
+ * $FreeBSD$
+ */
+
+void	lm_init (void);
+void	lm_fini (void);
+char *	lm_find (const char *, const char *);

libexec/rtld-elf/rtld.1

@@ -157,6 +157,8 @@ are recognized and have their usual meaning.
 .Sh FILES
 .Bl -tag -width indent
 .It Pa /var/run/ld-elf.so.hints
+.It Pa /etc/libmap.conf
+The libmap configuration file. 
 .El
 .Sh SEE ALSO
 .Xr ld 1 ,

libexec/rtld-elf/rtld.c

@@ -52,6 +52,9 @@
 
 #include "debug.h"
 #include "rtld.h"
+#ifdef WITH_LIBMAP
+#include "libmap.h"
+#endif
 
 #define END_SYM		"_end"
 #define PATH_RTLD	"/usr/libexec/ld-elf.so.1"
@@ -366,6 +369,10 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
     sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
     sym_zero.st_shndx = SHN_UNDEF;
 
+#ifdef WITH_LIBMAP
+    lm_init();
+#endif
+
     dbg("loading LD_PRELOAD libraries");
     if (load_preload_objects() == -1)
 	die();
@@ -802,19 +809,25 @@ elf_hash(const char *name)
  *   /usr/lib
  */
 static char *
-find_library(const char *name, const Obj_Entry *refobj)
+find_library(const char *xname, const Obj_Entry *refobj)
 {
     char *pathname;
+    char *name;
 
-    if (strchr(name, '/') != NULL) {	/* Hard coded pathname */
-	if (name[0] != '/' && !trust) {
+    if (strchr(xname, '/') != NULL) {	/* Hard coded pathname */
+	if (xname[0] != '/' && !trust) {
 	    _rtld_error("Absolute pathname required for shared object \"%s\"",
-	      name);
+	      xname);
 	    return NULL;
 	}
-	return xstrdup(name);
+	return xstrdup(xname);
     }
 
+#ifdef WITH_LIBMAP
+    if ((name = lm_find(refobj->path, xname)) == NULL)
+#endif
+	name = (char *)xname;
+
     dbg(" Searching for \"%s\"", name);
 
     if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
@@ -1468,6 +1481,9 @@ rtld_exit(void)
 	obj->refcount = 0;
     objlist_call_fini(&list_fini);
     /* No need to remove the items from the list, since we are exiting. */
+#ifdef WITH_LIBMAP
+    lm_fini();
+#endif
 }
 
 static void *

share/man/man5/Makefile

@@ -6,7 +6,7 @@ MAN=	a.out.5 acct.5 core.5 devfs.5 device.hints.5 \
 	dir.5 disktab.5 drivers.conf.5 \
 	elf.5 ethers.5 fbtab.5 fdescfs.5 forward.5 fs.5 fstab.5 group.5 \
 	hesiod.conf.5 \
-	hosts.5 hosts.equiv.5 hosts.lpd.5 intro.5 link.5 \
+	hosts.5 hosts.equiv.5 hosts.lpd.5 intro.5 libmap.conf.5 link.5 \
 	linprocfs.5 mailer.conf.5 make.conf.5 moduli.5 motd.5 msdosfs.5 \
 	networks.5 \
 	nsswitch.conf.5 \

share/man/man5/libmap.conf.5

@@ -0,0 +1,111 @@
+.\" Copyright (c) 2003 Matthew N. Dodd <winter@jurai.net>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.\" Note: The date here should be updated whenever a non-trivial
+.\" change is made to the manual page.
+.Dd April 7, 2003
+.Dt LIBMAP.CONF 5
+.Os
+.Sh NAME
+.Nm libmap.conf
+.Nd "configuration file for dynamic object dependency mapping"
+.Sh DESCRIPTION
+The
+.Em libmap
+functionality of
+.Nm ld-elf.so.1
+allows dynamic object dependencies to be mapped to arbitrary
+names.
+.Pp
+The configuration file consists of two whitespace separated columns; the 
+left hand side containing the mapping candidate and the right hand
+side containing the mapping.  Dependencies are matched against candidates
+and replaced with the mappings.
+.Pp
+Constrained mappings may be specified by enclosing the name of the
+executable or library in brackets.  All mappings following a constraint
+will only be evaluated for that constraint.  Currently, constraints
+are matched literally so that an executable with a fully qualified pathname 
+will only match the same constraint.  This means that
+.Em /usr/bin/foo
+will not match a constraint for
+.Em foo
+and vise-versa.
+.Pp
+WARNING!  Constrained mappings must never appear first in the configuration
+file.  While there is a way to specify the
+.Dq default
+constraint, its use is not recommended.
+.Pp
+The most common use at the date of writing is for allowing multiple
+POSIX threading libraries to be used on a system without relinking or
+changing symlinks.
+.Pp
+In order to enable this feature please see 
+.Pa src/libexec/rtld-elf/Makefile .
+.Sh EXAMPLE
+.Bd -literal
+
+# /etc/libmap.conf
+#
+# candidate		mapping
+#
+libc_r.so.5		libthr.so.1	# Everything uses 'libthr'
+libc_r.so		libthr.so
+
+[/usr/local/bin/mplayer]		# 'mplayer' uses libc_r.
+libc_r.so.5		libc_r.so.5
+libc_r.so		libc_r.so
+
+[mplayer]
+libc_r.so.5		libc_r.so.5
+libc_r.so		libc_r.so
+
+[/usr/local/sbin/httpd]			# Apache uses libkse
+libc_r.so.5		libkse.so.1
+libc_r.so		libkse.so
+
+[httpd]
+libc_r.so.5		libkse.so.1
+libc_r.so		libkse.so
+.Ed
+.Sh FILES
+.Bl -tag -width ".Pa /etc/libmap.conf" -compact
+.It Pa /etc/libmap.conf
+The libmap configuration file.
+.El
+.Sh SEE ALSO
+.Xr rtld 1
+.Xr ldd 1
+.Sh HISTORY
+The
+.Nm
+manual page and libmap.conf functionality first appeared in
+.Fx 5.1 .
+.Sh AUTHORS
+This
+manual page was written by
+.An Matthew N. Dodd <winter@jurai.net> .