modinfo: Allow to force arg as module name

If the Linux kernel or userspace sets an alias with the same name as a
module, they force the tools to use that. However in some situations it
may be desired to query the module itself. Getting the module
information through modinfo is one such situation. So, add a option to
modinfo to explicitly instruct it to handle the argument as a module
name.

Example, when trying to output information about the crc32 module that
is builtin:

	$ modinfo crc32
	filename:       /lib/modules/5.15.19-1-MANJARO/kernel/arch/x86/crypto/crc32-pclmul.ko.zst
	alias:          crypto-crc32-pclmul
	alias:          crc32-pclmul
	alias:          crypto-crc32
	alias:          crc32
	license:        GPL
	author:         Alexander Boyko <alexander_boyko@xyratex.com>
	srcversion:     B6B2FF9236731E69418A2E5
	alias:          cpu:type:x86,ven*fam*mod*:feature:*0081*
	depends:
	retpoline:      Y
	intree:         Y
	name:           crc32_pclmul
	vermagic:       5.15.19-1-MANJARO SMP preempt mod_unload
	sig_id:         PKCS#7
	signer:         Build time autogenerated kernel key
	sig_key:        77:FB:AA:BD:48:78:A4:C6:56:18:9A:7E:A6:F3:29:3E:C5:6B:E9:37
	sig_hashalgo:   sha512
	signature:      30:65:02:31:00:B0:D4:49:9D:1D:F1:71:4C:3C:BB:70:B2:3E:46:5D:
			38:5A:F1:00:95:FD:7A:96:C4:2C:24:35:A2:1B:0B:A8:1C:29:6F:02:
			7A:68:EE:BA:A4:1C:01:4B:86:39:15:3E:66:02:30:7F:7A:66:5E:F2:
			2F:98:73:3D:AD:96:66:81:8B:94:6E:F3:3F:44:0F:85:E1:73:3A:9E:
			F9:C4:BE:9B:88:02:BD:83:04:B9:2E:72:0B:93:BC:82:B6:A1:1B:6A:
			C2:ED:8C
	filename:       /lib/modules/5.15.19-1-MANJARO/kernel/crypto/crc32_generic.ko.zst
	alias:          crypto-crc32-generic
	alias:          crc32-generic
	alias:          crypto-crc32
	alias:          crc32
	license:        GPL
	description:    CRC32 calculations wrapper for lib/crc32
	author:         Alexander Boyko <alexander_boyko@xyratex.com>
	srcversion:     F08036C38DDB06BCD1E6091
	depends:
	retpoline:      Y
	intree:         Y
	name:           crc32_generic
	vermagic:       5.15.19-1-MANJARO SMP preempt mod_unload
	sig_id:         PKCS#7
	signer:         Build time autogenerated kernel key
	sig_key:        77:FB:AA:BD:48:78:A4:C6:56:18:9A:7E:A6:F3:29:3E:C5:6B:E9:37
	sig_hashalgo:   sha512
	signature:      30:65:02:31:00:E3:9E:C8:80:15:0E:D7:74:96:B5:25:EA:32:F7:DF:
			E9:FC:3C:82:D9:B9:B9:37:C5:20:8D:06:31:02:62:B3:54:E8:DF:F2:
			7E:E2:7C:A4:CF:49:17:CB:75:DF:2C:7A:2F:02:30:25:DE:7C:2A:2C:
			97:3F:65:16:76:B3:71:FB:62:DB:8F:F3:33:65:77:98:F3:57:ED:D7:
			87:78:FF:C2:04:55:70:00:10:63:1E:B2:FE:22:D8:E5:6D:5F:95:4E:
			7D:2C:6B

That is because the Linux kernel exports "crc32" as an alias to those modules,
besides being a module itself:

	$ grep crc32 /lib/modules/$(uname -r)/modules.builtin
	kernel/lib/crc32.ko
	$ $ grep "alias crc32 " /lib/modules/$(uname -r)/modules.alias
	alias crc32 crc32_pclmul
	alias crc32 crc32_generic

With the new -m|--modname option it's possible to query the information about this (builtin)
module explicitly:

	$ modinfo --modname crc32
	name:           crc32
	filename:       (builtin)
	license:        GPL
	file:           lib/crc32
	description:    Various CRC32 calculations
	author:         Matt Domsch <Matt_Domsch@dell.com>

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 28 insertions, 2 deletions

diff --git a/tools/modinfo.c b/tools/modinfo.c
index f51b7e4..d0aab20 100644
--- a/tools/modinfo.c
+++ b/tools/modinfo.c
@@ -293,6 +293,24 @@ static int modinfo_path_do(struct kmod_ctx *ctx, const char *path)
 	return err;
 }
 
+static int modinfo_name_do(struct kmod_ctx *ctx, const char *name)
+{
+	struct kmod_module *mod = NULL;
+	int err;
+
+	err = kmod_module_new_from_name_lookup(ctx, name, &mod);
+	if (err < 0 || mod == NULL) {
+		ERR("Module name %s not found.\n", name);
+		return err < 0 ? err : -ENOENT;
+	}
+
+	err = modinfo_do(mod);
+	kmod_module_unref(mod);
+
+	return err;
+}
+
+
 static int modinfo_alias_do(struct kmod_ctx *ctx, const char *alias)
 {
 	struct kmod_list *l, *list = NULL;
@@ -318,7 +336,7 @@ static int modinfo_alias_do(struct kmod_ctx *ctx, const char *alias)
 	return err;
 }
 
-static const char cmdopts_s[] = "adlpn0F:k:b:Vh";
+static const char cmdopts_s[] = "adlpn0mF:k:b:Vh";
 static const struct option cmdopts[] = {
 	{"author", no_argument, 0, 'a'},
 	{"description", no_argument, 0, 'd'},
@@ -326,6 +344,7 @@ static const struct option cmdopts[] = {
 	{"parameters", no_argument, 0, 'p'},
 	{"filename", no_argument, 0, 'n'},
 	{"null", no_argument, 0, '0'},
+	{"modname", no_argument, 0, 'm'},
 	{"field", required_argument, 0, 'F'},
 	{"set-version", required_argument, 0, 'k'},
 	{"basedir", required_argument, 0, 'b'},
@@ -345,6 +364,7 @@ static void help(void)
 		"\t-p, --parameters            Print only 'parm'\n"
 		"\t-n, --filename              Print only 'filename'\n"
 		"\t-0, --null                  Use \\0 instead of \\n\n"
+		"\t-m, --modname               Handle argument as module name instead of alias or filename\n"
 		"\t-F, --field=FIELD           Print only provided FIELD\n"
 		"\t-k, --set-version=VERSION   Use VERSION instead of `uname -r`\n"
 		"\t-b, --basedir=DIR           Use DIR as filesystem root for /lib/modules\n"
@@ -372,6 +392,7 @@ static int do_modinfo(int argc, char *argv[])
 	const char *kversion = NULL;
 	const char *root = NULL;
 	const char *null_config = NULL;
+	bool arg_is_modname = false;
 	int i, err;
 
 	for (;;) {
@@ -398,6 +419,9 @@ static int do_modinfo(int argc, char *argv[])
 		case '0':
 			separator = '\0';
 			break;
+		case 'm':
+			arg_is_modname = true;
+			break;
 		case 'F':
 			field = optarg;
 			break;
@@ -454,7 +478,9 @@ static int do_modinfo(int argc, char *argv[])
 		const char *name = argv[i];
 		int r;
 
-		if (is_module_filename(name))
+		if (arg_is_modname)
+			r = modinfo_name_do(ctx, name);
+		else if (is_module_filename(name))
 			r = modinfo_path_do(ctx, name);
 		else
 			r = modinfo_alias_do(ctx, name);