Implement ldconfig functionality for ELF. The hints are stored in

a different file than the a.out hints, namely, "/var/run/ld-elf.so.hints".
These hints consist only of the directory search path.  There is
no hash table as in the a.out hints, because ELF doesn't have to
search for the file with the highest minor version number.  (It
doesn't have minor version numbers at all.)

A single run of ldconfig updates either the a.out hints or the ELF
hints, but not both.  The set of hints to process is selected in
the usual way, via /etc/objformat, or ${OBJFORMAT}, or the "-aout"
or "-elf" command line option.  The rationale is that you probably
want to search different directories for ELF than for a.out.

"ldconfig -r" is faked up to produce output like we are used to,
except that for ELF there are no minor version numbers.  This should
enable "ldconfig -r" to be used for checking LIB_DEPENDS in ports
even for ELF.

I implemented the ELF functionality in a new source file, with an
eye toward eliminating the a.out code entirely at some point in
the future.

1 files changed, 50 insertions, 3 deletions

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index c52efa0..5cb35e0 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -22,7 +22,7 @@
  * (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 1.6 1998/09/02 02:51:12 jdp Exp $
+ *      $Id: rtld.c,v 1.7 1998/09/04 19:03:57 dfr Exp $
  */
 
 /*
@@ -75,6 +75,7 @@ static void digest_dynamic(Obj_Entry *);
 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t);
 static Obj_Entry *dlcheck(void *);
 static char *find_library(const char *, const Obj_Entry *);
+static const char *gethints(void);
 static void init_rtld(caddr_t);
 static bool is_exported(const Elf_Sym *);
 static void linkmap_add(Obj_Entry *);
@@ -626,6 +627,12 @@ elf_hash(const char *name)
  *
  * If the second argument is non-NULL, then it refers to an already-
  * loaded shared object, whose library search path will be searched.
+ *
+ * The search order is:
+ *   LD_LIBRARY_PATH
+ *   ldconfig hints
+ *   rpath in the referencing file
+ *   /usr/lib
  */
 static char *
 find_library(const char *name, const Obj_Entry *refobj)
@@ -643,9 +650,10 @@ find_library(const char *name, const Obj_Entry *refobj)
 
     dbg(" Searching for \"%s\"", name);
 
-    if ((refobj != NULL &&
+    if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
+      (pathname = search_library_path(name, gethints())) != NULL ||
+      (refobj != NULL &&
       (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
-      (pathname = search_library_path(name, ld_library_path)) != NULL ||
       (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
 	return pathname;
 
@@ -747,6 +755,45 @@ find_symdef(unsigned long symnum, const Obj_Entry *refobj,
 }
 
 /*
+ * Return the search path from the ldconfig hints file, reading it if
+ * necessary.  Returns NULL if there are problems with the hints file,
+ * or if the search path there is empty.
+ */
+static const char *
+gethints(void)
+{
+    static char *hints;
+
+    if (hints == NULL) {
+	int fd;
+	struct elfhints_hdr hdr;
+	char *p;
+
+	/* Keep from trying again in case the hints file is bad. */
+	hints = "";
+
+	if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
+	    return NULL;
+	if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
+	  hdr.magic != ELFHINTS_MAGIC ||
+	  hdr.version != 1) {
+	    close(fd);
+	    return NULL;
+	}
+	p = xmalloc(hdr.dirlistlen + 1);
+	if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
+	  read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
+	    free(p);
+	    close(fd);
+	    return NULL;
+	}
+	hints = p;
+	close(fd);
+    }
+    return hints[0] != '\0' ? hints : NULL;
+}
+
+/*
  * Initialize the dynamic linker.  The argument is the address at which
  * the dynamic linker has been mapped into memory.  The primary task of
  * this function is to relocate the dynamic linker.