modprobe: Allow passing path to module

This is useful to kernel module developers for testing a just compiled
module: instead of using insmod, they can load the module from the path
while getting all the benefits of modprobe (e.g. module dependency
resolution).

v2:
  - Add test for relative path as well. (Lucas)
  - Add note warning about modules with dependencies not matching the
    installed depmod database. (Lucas)

Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>

man/modprobe.xml

@@ -115,6 +115,13 @@
       kernel (in addition to any options listed in the configuration
       file).
     </para>
+    <para>
+      When loading modules, <replaceable>modulename</replaceable> can also
+      be a path to the module. If the path is relative, it must
+      explicitly start with "./". Note that this may fail when using a
+      path to a module with dependencies not matching the installed depmod
+      database.
+    </para>
   </refsect1>
 
   <refsect1><title>OPTIONS</title>

testsuite/populate-modules.sh

@@ -56,6 +56,8 @@ map=(
     ["test-modprobe/alias-to-none/lib/modules/4.4.4/kernel/"]="mod-simple.ko"
     ["test-modprobe/module-param-kcmdline/lib/modules/4.4.4/kernel/"]="mod-simple.ko"
     ["test-modprobe/external/lib/modules/external/"]="mod-simple.ko"
+    ["test-modprobe/module-from-abspath/home/foo/"]="mod-simple.ko"
+    ["test-modprobe/module-from-relpath/home/foo/"]="mod-simple.ko"
     ["test-depmod/modules-order-compressed/lib/modules/4.4.4/kernel/drivers/block/cciss.ko"]="mod-fake-cciss.ko"
     ["test-depmod/modules-order-compressed/lib/modules/4.4.4/kernel/drivers/scsi/hpsa.ko"]="mod-fake-hpsa.ko"
     ["test-depmod/modules-order-compressed/lib/modules/4.4.4/kernel/drivers/scsi/scsi_mod.ko"]="mod-fake-scsi-mod.ko"

testsuite/rootfs-pristine/test-modprobe/module-from-abspath/lib/modules/4.4.4/modules.alias

@@ -0,0 +1 @@
+# Aliases extracted from modules themselves.

testsuite/rootfs-pristine/test-modprobe/module-from-abspath/lib/modules/4.4.4/modules.dep

@@ -0,0 +1 @@
+/lib/modules/external/mod-simple.ko:

testsuite/rootfs-pristine/test-modprobe/module-from-abspath/lib/modules/4.4.4/modules.softdep

@@ -0,0 +1 @@
+# Soft dependencies extracted from modules themselves.

testsuite/rootfs-pristine/test-modprobe/module-from-abspath/lib/modules/4.4.4/modules.symbols

@@ -0,0 +1 @@
+# Aliases for symbols, used by symbol_request().

testsuite/rootfs-pristine/test-modprobe/module-from-relpath/lib/modules/4.4.4/modules.alias

@@ -0,0 +1 @@
+# Aliases extracted from modules themselves.

testsuite/rootfs-pristine/test-modprobe/module-from-relpath/lib/modules/4.4.4/modules.dep

@@ -0,0 +1 @@
+/lib/modules/external/mod-simple.ko:

testsuite/rootfs-pristine/test-modprobe/module-from-relpath/lib/modules/4.4.4/modules.softdep

@@ -0,0 +1 @@
+# Soft dependencies extracted from modules themselves.

testsuite/rootfs-pristine/test-modprobe/module-from-relpath/lib/modules/4.4.4/modules.symbols

@@ -0,0 +1 @@
+# Aliases for symbols, used by symbol_request().

testsuite/test-modprobe.c

@@ -422,4 +422,54 @@ DEFINE_TEST(modprobe_external,
 	.modules_loaded = "mod-simple",
 	);
 
+static noreturn int modprobe_module_from_abspath(const struct test *t)
+{
+	const char *progname = ABS_TOP_BUILDDIR "/tools/modprobe";
+	const char *const args[] = {
+		progname,
+		"/home/foo/mod-simple.ko",
+		NULL,
+	};
+
+	test_spawn_prog(progname, args);
+	exit(EXIT_FAILURE);
+}
+DEFINE_TEST(modprobe_module_from_abspath,
+	.description = "check modprobe able to load module given as an absolute path",
+	.config = {
+		[TC_UNAME_R] = "4.4.4",
+		[TC_ROOTFS] = TESTSUITE_ROOTFS "test-modprobe/module-from-abspath",
+		[TC_INIT_MODULE_RETCODES] = "",
+	},
+	.modules_loaded = "mod-simple",
+	);
+
+static noreturn int modprobe_module_from_relpath(const struct test *t)
+{
+	const char *progname = ABS_TOP_BUILDDIR "/tools/modprobe";
+	const char *const args[] = {
+		progname,
+		"./mod-simple.ko",
+		NULL,
+	};
+
+	if (chdir("/home/foo") != 0) {
+		perror("failed to change into /home/foo");
+		exit(EXIT_FAILURE);
+	}
+
+	test_spawn_prog(progname, args);
+	exit(EXIT_FAILURE);
+}
+DEFINE_TEST(modprobe_module_from_relpath,
+	.description = "check modprobe able to load module given as a relative path",
+	.config = {
+		[TC_UNAME_R] = "4.4.4",
+		[TC_ROOTFS] = TESTSUITE_ROOTFS "test-modprobe/module-from-relpath",
+		[TC_INIT_MODULE_RETCODES] = "",
+	},
+	.need_spawn = true,
+	.modules_loaded = "mod-simple",
+	);
+
 TESTSUITE_MAIN();

tools/modprobe.c

@@ -614,14 +614,23 @@ static int insmod(struct kmod_ctx *ctx, const char *alias,
 						const char *extra_options)
 {
 	struct kmod_list *l, *list = NULL;
+	struct kmod_module *mod = NULL;
 	int err, flags = 0;
 
-	err = kmod_module_new_from_lookup(ctx, alias, &list);
-
-	if (list == NULL || err < 0) {
-		LOG("Module %s not found in directory %s\n", alias,
-			ctx ? kmod_get_dirname(ctx) : "(missing)");
-		return -ENOENT;
+	if (strncmp(alias, "/", 1) == 0 || strncmp(alias, "./", 2) == 0) {
+		err = kmod_module_new_from_path(ctx, alias, &mod);
+		if (err < 0) {
+			LOG("Failed to get module from path %s: %s\n", alias,
+				strerror(-err));
+			return -ENOENT;
+		}
+	} else {
+		err = kmod_module_new_from_lookup(ctx, alias, &list);
+		if (list == NULL || err < 0) {
+			LOG("Module %s not found in directory %s\n", alias,
+				ctx ? kmod_get_dirname(ctx) : "(missing)");
+			return -ENOENT;
+		}
 	}
 
 	if (strip_modversion || force)
@@ -642,13 +651,18 @@ static int insmod(struct kmod_ctx *ctx, const char *alias,
 	if (first_time)
 		flags |= KMOD_PROBE_FAIL_ON_LOADED;
 
-	kmod_list_foreach(l, list) {
-		struct kmod_module *mod = kmod_module_get_module(l);
+	/* If module is loaded from path */
+	if (mod != NULL) {
 		err = insmod_insert(mod, flags, extra_options);
 		kmod_module_unref(mod);
+	} else {
+		kmod_list_foreach(l, list) {
+			mod = kmod_module_get_module(l);
+			err = insmod_insert(mod, flags, extra_options);
+			kmod_module_unref(mod);
+		}
+		kmod_module_unref_list(list);
 	}
-
-	kmod_module_unref_list(list);
 	return err;
 }