depmod: Stop opening modules.modinfo once per module

Since the addition of modules.aliases.bin, depmod has to open that
index multiple times and parse it over and over again:

	$ sudo strace -e openat  ./tools/depmod 2>&1 | grep modules.builtin.modinfo  | wc -l
	299
	$ time sudo  ./tools/depmod
	real    0m7.814s
	user    0m7.571s
	sys     0m0.237s

Rework the logic in depmod so it does everything: open, read and parse. The
format is very straightforward and we don't need to keep it in a data structure
since we only want to add the result to a index. New output:

	$ sudo strace -e openat  ./tools/depmod 2>&1 | grep modules.builtin.modinfo  | wc -l
	1
	$ time sudo  ./tools/depmod
	real    0m7.663s
	user    0m7.516s
	sys     0m0.139s

Indexes still match:

	$ cmp /tmp/modules.builtin.alias.bin.new
	/tmp/modules.builtin.alias.bin.old; echo $?
	0

Fix: https://github.com/kmod-project/kmod/issues/11

diff --git a/tools/depmod.c b/tools/depmod.c
index ac6ead823aa682b5afd73f6481658286e40a5273..07a35baebd0f78122e732af98a742a8e0ed5a414 100644 (file)
--- a/tools/depmod.c
+++ b/tools/depmod.c
@@ -2346,6 +2346,102 @@ static int output_builtin_bin(struct depmod *depmod, FILE *out)
        return 0;
 }
 
+static int flush_stream(FILE *in, int endchar)
+{
+       size_t i = 0;
+       int c;
+
+       for (c = fgetc(in);
+            c != EOF && c != endchar && c != '\0';
+            c = fgetc(in))
+               ;
+
+       return c == endchar ? i : 0;
+}
+
+static int flush_stream_to(FILE *in, int endchar, char *dst, size_t dst_sz)
+{
+       size_t i = 0;
+       int c;
+
+       for (c = fgetc(in);
+            c != EOF && c != endchar && c != '\0' && i < dst_sz;
+            c = fgetc(in))
+               dst[i++] = c;
+
+       if (i == dst_sz) {
+               WRN("Could not flush stream: %d. Partial content: %.*s\n",
+                   ENOSPC, (int) dst_sz, dst);
+       }
+
+       return c == endchar ? i : 0;
+}
+
+static int output_builtin_alias_bin(struct depmod *depmod, FILE *out)
+{
+       FILE *in;
+       struct index_node *idx;
+       int ret;
+
+       if (out == stdout)
+               return 0;
+
+       in = dfdopen(depmod->cfg->dirname, "modules.builtin.modinfo", O_RDONLY, "r");
+       if (in == NULL)
+               return 0;
+
+       idx = index_create();
+       if (idx == NULL) {
+               fclose(in);
+               return -ENOMEM;
+       }
+
+       /* format: modname.key=value\0 */
+       while (!feof(in) && !ferror(in)) {
+               char alias[PATH_MAX];
+               char modname[PATH_MAX];
+               char value[PATH_MAX];
+               size_t len;
+
+               len = flush_stream_to(in, '.', modname, sizeof(modname));
+               modname[len] = '\0';
+               if (!len)
+                       continue;
+
+               len = flush_stream_to(in, '=', value, sizeof(value));
+               value[len] = '\0';
+               if (!streq(value, "alias")) {
+                       flush_stream(in, '\0');
+                       continue;
+               }
+
+               len = flush_stream_to(in, '\0', value, sizeof(value));
+               value[len] = '\0';
+               if (!len)
+                       continue;
+
+               alias[0] = '\0';
+               if (alias_normalize(value, alias, NULL) < 0) {
+                       WRN("Unmatched bracket in %s\n", value);
+                       continue;
+               }
+
+               index_insert(idx, alias, modname, 0);
+       }
+
+       if (ferror(in)) {
+               ret = -EINVAL;
+       } else {
+               index_write(idx, out);
+               ret = 0;
+       }
+
+       index_destroy(idx);
+       fclose(in);
+
+       return ret;
+}
+
 static int output_devname(struct depmod *depmod, FILE *out)
 {
        size_t i;
@@ -2403,68 +2499,6 @@ static int output_devname(struct depmod *depmod, FILE *out)
        return 0;
 }
 
-static int output_builtin_alias_bin(struct depmod *depmod, FILE *out)
-{
-       int ret = 0;
-       struct index_node *idx;
-       struct kmod_list *l, *builtin = NULL;
-
-       if (out == stdout)
-               return 0;
-
-       idx = index_create();
-       if (idx == NULL)
-               return -ENOMEM;
-
-       ret = kmod_module_get_builtin(depmod->ctx, &builtin);
-       if (ret < 0) {
-               if (ret == -ENOENT)
-                       ret = 0;
-               goto out;
-       }
-
-       kmod_list_foreach(l, builtin) {
-               struct kmod_list *ll, *info_list = NULL;
-               struct kmod_module *mod = l->data;
-               const char *modname = kmod_module_get_name(mod);
-
-               ret = kmod_module_get_info(mod, &info_list);
-               if (ret < 0)
-                       goto out;
-
-               kmod_list_foreach(ll, info_list) {
-                       char alias[PATH_MAX];
-                       const char *key = kmod_module_info_get_key(ll);
-                       const char *value = kmod_module_info_get_value(ll);
-
-                       if (!streq(key, "alias"))
-                               continue;
-
-                       alias[0] = '\0';
-                       if (alias_normalize(value, alias, NULL) < 0) {
-                               WRN("Unmatched bracket in %s\n", value);
-                               continue;
-                       }
-
-                       index_insert(idx, alias, modname, 0);
-               }
-
-               kmod_module_info_free_list(info_list);
-       }
-
-out:
-       /* do not bother writing the index if we are going to discard it */
-       if (ret > 0)
-               index_write(idx, out);
-
-       if (builtin)
-               kmod_module_unref_list(builtin);
-
-       index_destroy(idx);
-
-       return ret;
-}
-
 static int depmod_output(struct depmod *depmod, FILE *out)
 {
        static const struct depfile {