Implement dlsym(RTLD_NEXT, symbol).

8 files changed, 179 insertions, 35 deletions

diff --git a/gnu/usr.bin/ld/rtld/rtld.c b/gnu/usr.bin/ld/rtld/rtld.c
index b2c478c903a2..ea33fe897a1c 100644
--- a/gnu/usr.bin/ld/rtld/rtld.c
+++ b/gnu/usr.bin/ld/rtld/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.
  *
- *	$Id$
+ *	$Id: rtld.c,v 1.46 1997/02/22 15:46:48 peter Exp $
  */
 
 #include <sys/param.h>
@@ -204,9 +204,10 @@ static int		__dlclose __P((void *));
 static void		*__dlsym __P((void *, char *));
 static char		*__dlerror __P((void));
 static void		__dlexit __P((void));
+static void		*__dlsym3 __P((void *, char *, void *));
 
 static struct ld_entry	ld_entry = {
-	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit
+	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
 };
 
        void		xprintf __P((char *, ...));
@@ -411,7 +412,7 @@ struct _dynamic		*dp;
 	(void)close(crtp->crt_ldfd);
 	anon_close();
 
-	return LDSO_VERSION_HAS_DLEXIT;
+	return LDSO_VERSION_HAS_DLSYM3;
 }
 
 void
@@ -1896,26 +1897,77 @@ __dlclose(fd)
 	return 0;
 }
 
+/*
+ * This form of dlsym is obsolete.  Current versions of crt0 don't call
+ * it.  It can still be called by old executables that were linked with
+ * old versions of crt0.
+ */
 	static void *
 __dlsym(fd, sym)
 	void	*fd;
 	char	*sym;
 {
-	struct so_map	*smp = (struct so_map *)fd, *src_map = NULL;
+	if (fd == RTLD_NEXT) {
+		generror("RTLD_NEXT not supported by this version of"
+		    " /usr/lib/crt0.o");
+		return NULL;
+	}
+	return __dlsym3(fd, sym, NULL);
+}
+
+	static void *
+__dlsym3(fd, sym, retaddr)
+	void	*fd;
+	char	*sym;
+	void	*retaddr;
+{
+	struct so_map	*smp;
+	struct so_map	*src_map;
 	struct nzlist	*np;
 	long		addr;
 
-	/*
-	 * Restrict search to passed map if dlopen()ed.
-	 */
-	if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
-		src_map = smp;
+	if (fd == RTLD_NEXT) {
+		/* Find the shared object that contains the caller. */
+		for (smp = link_map_head;  smp != NULL;  smp = smp->som_next) {
+			void *textbase = smp->som_addr + LM_TXTADDR(smp);
+			void *textlimit = LM_ETEXT(smp);
 
-	np = lookup(sym, &src_map, 1);
-	if (np == NULL)
+			if (textbase <= retaddr && retaddr < textlimit)
+				break;
+		}
+		if (smp == NULL) {
+			generror("Cannot determine caller's shared object");
+			return NULL;
+		}
+		smp = smp->som_next;
+		if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
+			smp = smp->som_next;
+		if (smp == NULL) {
+			generror("No next shared object for RTLD_NEXT");
+			return NULL;
+		}
+		do {
+			src_map = smp;
+			np = lookup(sym, &src_map, 1);
+		} while (np == NULL && (smp = smp->som_next) != NULL);
+	} else {
+		smp = (struct so_map *)fd;
+		src_map = NULL;
+
+		/*
+		 * Restrict search to passed map if dlopen()ed.
+		 */
+		if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
+			src_map = smp;
+
+		np = lookup(sym, &src_map, 1);
+	}
+
+	if (np == NULL) {
+		generror("Undefined symbol");
 		return NULL;
+	}
 
-	/* Fixup jmpslot so future calls transfer directly to target */
 	addr = np->nz_value;
 	if (src_map)
 		addr += (long)src_map->som_addr;
diff --git a/include/link.h b/include/link.h
index 937fffea543f..0b55dca0fad9 100644
--- a/include/link.h
+++ b/include/link.h
@@ -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: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
+ *	$Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
  */
 
 /*
@@ -167,6 +167,7 @@ struct so_debug {
  */
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
+#define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -179,6 +180,7 @@ struct ld_entry {
 	void	*(*dlsym) __P((void *, char *));	/* NONE */
 	char	*(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
+	void	*(*dlsym3) __P((void *, char *, void *));  /* HAS_DLSYM3 */
 };
 
 /*
diff --git a/lib/csu/i386/crt0.c b/lib/csu/i386/crt0.c
index 5f7e4ab724ce..4d217fb08cea 100644
--- a/lib/csu/i386/crt0.c
+++ b/lib/csu/i386/crt0.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.
  *
- *	$Id$
+ *	$Id: crt0.c,v 1.29 1997/02/22 14:57:44 peter Exp $
  */
 
 #include <sys/param.h>
@@ -94,6 +94,8 @@ static char		empty[1];
 char			*__progname = empty;
 char			**environ;
 
+static int		ldso_version;
+
 extern	unsigned char	etext;
 extern	unsigned char	eprol asm ("eprol");
 extern			start() asm("start");
@@ -194,7 +196,6 @@ __do_dynamic_link ()
 	struct exec	hdr;
 	char		*ldso;
 	int		(*entry)();
-	int		ret;
 
 #ifdef DEBUG
 	/* Provision for alternate ld.so - security risk! */
@@ -254,14 +255,14 @@ __do_dynamic_link ()
 	crt.crt_ldentry = NULL;
 
 	entry = (int (*)())(crt.crt_ba + sizeof hdr);
-	ret = (*entry)(CRT_VERSION_BSD_4, &crt);
+	ldso_version = (*entry)(CRT_VERSION_BSD_4, &crt);
 	ld_entry = crt.crt_ldentry;
-	if (ret == -1 && ld_entry == NULL) {
+	if (ldso_version == -1 && ld_entry == NULL) {
 		/* if version 4 not recognised, try version 3 */
-		ret = (*entry)(CRT_VERSION_BSD_3, &crt);
+		ldso_version = (*entry)(CRT_VERSION_BSD_3, &crt);
 		ld_entry = _DYNAMIC.d_entry;
 	}
-	if (ret == -1) {
+	if (ldso_version == -1) {
 		_PUTMSG("ld.so failed");
 		if (ld_entry != NULL) {
 			char *msg = (ld_entry->dlerror)();
@@ -277,7 +278,7 @@ __do_dynamic_link ()
 	}
 
 
-	if (ret >= LDSO_VERSION_HAS_DLEXIT)
+	if (ldso_version >= LDSO_VERSION_HAS_DLEXIT)
 		atexit(ld_entry->dlexit);
 
 	return;
@@ -316,7 +317,11 @@ char	*name;
 	if (ld_entry == NULL)
 		return NULL;
 
-	return (ld_entry->dlsym)(fd, name);
+	if (ldso_version >= LDSO_VERSION_HAS_DLSYM3) {
+		void *retaddr = *(&fd - 1);  /* XXX - ABI/machine dependent */
+		return (ld_entry->dlsym3)(fd, name, retaddr);
+	} else
+		return (ld_entry->dlsym)(fd, name);
 }
 
 
diff --git a/lib/csu/i386/dlfcn.h b/lib/csu/i386/dlfcn.h
index feadf90bc6c7..b6817fe03b26 100644
--- a/lib/csu/i386/dlfcn.h
+++ b/lib/csu/i386/dlfcn.h
@@ -43,6 +43,13 @@
 #define RTLD_LAZY	1	/* Bind function calls lazily */
 #define RTLD_NOW	2	/* Bind function calls immediately */
 
+/*
+ * Special handle argument for dlsym().  It causes the search for the
+ * symbol to begin in the next shared object after the one containing
+ * the caller.
+ */
+#define RTLD_NEXT	((void *) -1)
+
 __BEGIN_DECLS
 void *dlopen __P((char *, int));
 void *dlsym __P((void *, char *));
diff --git a/lib/csu/i386/dlopen.3 b/lib/csu/i386/dlopen.3
index 82651c6b510f..efd59be557f2 100644
--- a/lib/csu/i386/dlopen.3
+++ b/lib/csu/i386/dlopen.3
@@ -152,6 +152,28 @@ returns a null pointer if the symbol cannot be found, and sets an error
 condition which may be queried with
 .Fn dlerror .
 .Pp
+If
+.Fn dlsym
+is called with the special
+.Fa handle
+.Dv RTLD_NEXT ,
+then the search for the symbol is limited to the shared objects
+which were loaded after the one issuing the call to
+.Fn dlsym .
+Thus, if the function is called from the main program, all
+the shared libraries are searched.
+If it is called from a shared library, all subsequent shared
+libraries are searched.
+.Dv RTLD_NEXT
+is useful for implementing wrappers around library functions.
+For example, a wrapper function
+.Fn getpid
+could access the
+.Dq real
+.Fn getpid
+with
+.Li dlsym(RTLD_NEXT, \&"_getpid\&") .
+.Pp
 .Fn dlerror
 returns a null-terminated character string describing the last error that
 occurred during a call to
diff --git a/libexec/rtld-aout/rtld.c b/libexec/rtld-aout/rtld.c
index b2c478c903a2..ea33fe897a1c 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.
  *
- *	$Id$
+ *	$Id: rtld.c,v 1.46 1997/02/22 15:46:48 peter Exp $
  */
 
 #include <sys/param.h>
@@ -204,9 +204,10 @@ static int		__dlclose __P((void *));
 static void		*__dlsym __P((void *, char *));
 static char		*__dlerror __P((void));
 static void		__dlexit __P((void));
+static void		*__dlsym3 __P((void *, char *, void *));
 
 static struct ld_entry	ld_entry = {
-	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit
+	__dlopen, __dlclose, __dlsym, __dlerror, __dlexit, __dlsym3
 };
 
        void		xprintf __P((char *, ...));
@@ -411,7 +412,7 @@ struct _dynamic		*dp;
 	(void)close(crtp->crt_ldfd);
 	anon_close();
 
-	return LDSO_VERSION_HAS_DLEXIT;
+	return LDSO_VERSION_HAS_DLSYM3;
 }
 
 void
@@ -1896,26 +1897,77 @@ __dlclose(fd)
 	return 0;
 }
 
+/*
+ * This form of dlsym is obsolete.  Current versions of crt0 don't call
+ * it.  It can still be called by old executables that were linked with
+ * old versions of crt0.
+ */
 	static void *
 __dlsym(fd, sym)
 	void	*fd;
 	char	*sym;
 {
-	struct so_map	*smp = (struct so_map *)fd, *src_map = NULL;
+	if (fd == RTLD_NEXT) {
+		generror("RTLD_NEXT not supported by this version of"
+		    " /usr/lib/crt0.o");
+		return NULL;
+	}
+	return __dlsym3(fd, sym, NULL);
+}
+
+	static void *
+__dlsym3(fd, sym, retaddr)
+	void	*fd;
+	char	*sym;
+	void	*retaddr;
+{
+	struct so_map	*smp;
+	struct so_map	*src_map;
 	struct nzlist	*np;
 	long		addr;
 
-	/*
-	 * Restrict search to passed map if dlopen()ed.
-	 */
-	if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
-		src_map = smp;
+	if (fd == RTLD_NEXT) {
+		/* Find the shared object that contains the caller. */
+		for (smp = link_map_head;  smp != NULL;  smp = smp->som_next) {
+			void *textbase = smp->som_addr + LM_TXTADDR(smp);
+			void *textlimit = LM_ETEXT(smp);
 
-	np = lookup(sym, &src_map, 1);
-	if (np == NULL)
+			if (textbase <= retaddr && retaddr < textlimit)
+				break;
+		}
+		if (smp == NULL) {
+			generror("Cannot determine caller's shared object");
+			return NULL;
+		}
+		smp = smp->som_next;
+		if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_RTLD)
+			smp = smp->som_next;
+		if (smp == NULL) {
+			generror("No next shared object for RTLD_NEXT");
+			return NULL;
+		}
+		do {
+			src_map = smp;
+			np = lookup(sym, &src_map, 1);
+		} while (np == NULL && (smp = smp->som_next) != NULL);
+	} else {
+		smp = (struct so_map *)fd;
+		src_map = NULL;
+
+		/*
+		 * Restrict search to passed map if dlopen()ed.
+		 */
+		if (smp != NULL && LM_PRIVATE(smp)->spd_flags & RTLD_DL)
+			src_map = smp;
+
+		np = lookup(sym, &src_map, 1);
+	}
+
+	if (np == NULL) {
+		generror("Undefined symbol");
 		return NULL;
+	}
 
-	/* Fixup jmpslot so future calls transfer directly to target */
 	addr = np->nz_value;
 	if (src_map)
 		addr += (long)src_map->som_addr;
diff --git a/sys/sys/link_aout.h b/sys/sys/link_aout.h
index 937fffea543f..0b55dca0fad9 100644
--- a/sys/sys/link_aout.h
+++ b/sys/sys/link_aout.h
@@ -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: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
+ *	$Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
  */
 
 /*
@@ -167,6 +167,7 @@ struct so_debug {
  */
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
+#define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -179,6 +180,7 @@ struct ld_entry {
 	void	*(*dlsym) __P((void *, char *));	/* NONE */
 	char	*(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
+	void	*(*dlsym3) __P((void *, char *, void *));  /* HAS_DLSYM3 */
 };
 
 /*
diff --git a/sys/sys/link_elf.h b/sys/sys/link_elf.h
index 937fffea543f..0b55dca0fad9 100644
--- a/sys/sys/link_elf.h
+++ b/sys/sys/link_elf.h
@@ -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: link.h,v 1.12 1997/05/07 02:26:34 eivind Exp $
+ *	$Id: link.h,v 1.13 1997/05/07 20:00:00 eivind Exp $
  */
 
 /*
@@ -167,6 +167,7 @@ struct so_debug {
  */
 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
+#define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
 
 /*
  * Entry points into ld.so - user interface to the run-time linker.
@@ -179,6 +180,7 @@ struct ld_entry {
 	void	*(*dlsym) __P((void *, char *));	/* NONE */
 	char	*(*dlerror) __P((void));		/* NONE */
 	void	(*dlexit) __P((void));			/* HAS_DLEXIT */
+	void	*(*dlsym3) __P((void *, char *, void *));  /* HAS_DLSYM3 */
 };
 
 /*