depmod: simple memory optimization

function                                             old     new   delta
filename2modname                                      67      86     +19
parse_module                                         374     351     -23

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 14 insertions, 11 deletions

diff --git a/modutils/depmod.c b/modutils/depmod.c
index a41b3e440..37a8482d9 100644
--- a/modutils/depmod.c
+++ b/modutils/depmod.c
@@ -33,7 +33,6 @@ typedef struct module_info {
 static int FAST_FUNC parse_module(const char *fname, struct stat *sb UNUSED_PARAM,
                                 void *data, int depth UNUSED_PARAM)
 {
-        char modname[MODULE_NAME_LEN];
         module_info **first = (module_info **) data;
         char *image, *ptr;
         module_info *info;
@@ -51,11 +50,10 @@ static int FAST_FUNC parse_module(const char *fname, struct stat *sb UNUSED_PARA
 
         info->dnext = info->dprev = info;
         info->name = xstrdup(fname + 2); /* skip "./" */
-        info->modname = xstrdup(
-                filename2modname(
+        info->modname = filename2modname(
                         bb_get_last_path_component_nostrip(fname),
-                        modname
-        ));
+                        NULL
+        );
         for (ptr = image; ptr < image + len - 10; ptr++) {
                 if (strncmp(ptr, "depends=", 8) == 0) {
                         char *u;
@@ -250,11 +248,12 @@ int depmod_main(int argc UNUSED_PARAM, char **argv)
                 const char *fname = bb_basename(m->name);
                 filename2modname(fname, modname);
                 while (m->aliases) {
-                        /* Last word can well be m->modname instead,
-                         * but depmod from module-init-tools 3.4
-                         * uses module basename, i.e., no s/-/_/g.
-                         * (pathname and .ko.* are still stripped)
-                         * Mimicking that... */
+                        /*
+                         * Last word used to be a basename
+                         * (filename with path and .ko.* stripped)
+                         * at the time of module-init-tools 3.4.
+                         * kmod v.12 uses module name, i.e., s/-/_/g.
+                         */
                         printf("alias %s %s\n",
                                 (char*)llist_pop(&m->aliases),
                                 modname);
diff --git a/modutils/modutils.c b/modutils/modutils.c
index ff79d3fac..84300d931 100644
--- a/modutils/modutils.c
+++ b/modutils/modutils.c
@@ -47,13 +47,14 @@ int FAST_FUNC string_to_llist(char *string, llist_t **llist, const char *delim)
 
 char* FAST_FUNC filename2modname(const char *filename, char *modname)
 {
+        char local_modname[MODULE_NAME_LEN];
         int i;
         const char *from;
 
         if (filename == NULL)
                 return NULL;
         if (modname == NULL)
-                modname = xmalloc(MODULE_NAME_LEN);
+                modname = local_modname;
         // Disabled since otherwise "modprobe dir/name" would work
         // as if it is "modprobe name". It is unclear why
         // 'basenamization' was here in the first place.
@@ -63,6 +64,9 @@ char* FAST_FUNC filename2modname(const char *filename, char *modname)
                 modname[i] = (from[i] == '-') ? '_' : from[i];
         modname[i] = '\0';
 
+        if (modname == local_modname)
+                return xstrdup(modname);
+
         return modname;
 }