module: Actually use last component of DT_NEEDED pathname

The comment in module_load() claims that we strip everything from the
DT_NEEDED pathnames but the last component. That's not true as we
leave the initial '/', which works fine if the module is in the root
directory, but not so well if we're in a sub-directory. Worse still,
if the DT_NEEDED entry pathname doesn't include a '/' the module is
skipped entirely.

We should also be loading dependencies in reverse order, as modules
loaded because of DT_NEEDED entries may also have dependencies and
their dependencies should be loaded first.

Also, now we need the strrchr() implementation in the core, so move
strrchr.o into $CORELIBOBJS.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

2 files changed, 15 insertions, 13 deletions

diff --git a/com32/lib/Makefile b/com32/lib/Makefile
index daa7284e..75771d97 100644
--- a/com32/lib/Makefile
+++ b/com32/lib/Makefile
@@ -125,7 +125,7 @@ LIBOTHER_OBJS = \
 	strnlen.o							\
 	strncat.o strndup.o		\
 	stpncpy.o						\
-	strntoimax.o strntoumax.o strrchr.o strsep.o strspn.o strstr.o	\
+	strntoimax.o strntoumax.o strsep.o strspn.o strstr.o	\
 	strtoimax.o strtok.o strtol.o strtoll.o strtoul.o strtoull.o	\
 	strtoumax.o vprintf.o vsprintf.o		\
 	asprintf.o vasprintf.o			\
@@ -169,7 +169,7 @@ CORELIBOBJS = \
 	fputs.o fwrite2.o fwrite.o fgetc.o fclose.o errno.o lmalloc.o 	\
 	sys/err_read.o sys/err_write.o sys/null_read.o 			\
 	sys/stdcon_write.o sys/openconsole.o				\
-	syslinux/memscan.o						\
+	syslinux/memscan.o strrchr.o					\
 	libgcc/__ashldi3.o libgcc/__udivdi3.o				\
 	libgcc/__negdi2.o libgcc/__ashrdi3.o libgcc/__lshrdi3.o		\
 	libgcc/__muldi3.o libgcc/__udivmoddi4.o libgcc/__umoddi3.o	\
diff --git a/com32/lib/sys/module/elf_module.c b/com32/lib/sys/module/elf_module.c
index 3e373847..7d892aa9 100644
--- a/com32/lib/sys/module/elf_module.c
+++ b/com32/lib/sys/module/elf_module.c
@@ -513,11 +513,15 @@ int module_load(struct elf_module *module) {
 		/*
 		 * nr_needed can be modified by recursive calls to
 		 * module_load() so keep a local copy on the stack.
+		 *
+		 * Note that we have to load the dependencies in
+		 * reverse order.
 		 */
-		n = nr_needed;
-		for (i = 0; i < n; i++) {
+		n = nr_needed - 1;
+		for (i = n; i >= 0; i--) {
 			size_t len, j;
 			char *dep, *p;
+			char *argv[2] = { NULL, NULL };
 
 			dep = module->str_table + needed[i];
 
@@ -526,16 +530,14 @@ int module_load(struct elf_module *module) {
 			if (!len)
 				continue;
 
-			p = dep + len - 1;
-			while (j > 0 && *p && *p != '/') {
-				p--;
-				j--;
-			}
+			if (strchr(dep, '/')) {
+				p = strrchr(dep, '/');
+				p++;
+			} else
+				p = dep;
 
-			if (*p++ == '/') {
-				char *argv[2] = { p, NULL };
-				spawn_load(p, 1, argv);
-			}
+			argv[0] = p;
+			spawn_load(p, 1, argv);
 		}
 	}