kmod_config: optimize config files handling

 1) Allocate less by not sorting the result with qsort. Instead,
    insert the nodes in the correct order;
 2) Do not maintain the whole path in memory, but rely on openat()

diff --git a/libkmod/libkmod-config.c b/libkmod/libkmod-config.c
index 75fdbf15b679a22584acdf171c6c9de7729ee679..2859dd47265ad3194d70363900f463f49710a757 100644 (file)
--- a/libkmod/libkmod-config.c
+++ b/libkmod/libkmod-config.c
@@ -124,18 +124,26 @@ static void kmod_config_free_blacklist(struct kmod_config *config,
        config->blacklists = kmod_list_remove(l);
 }
 
-static int kmod_config_parse(struct kmod_config *config, const char *filename)
+/*
+ * Take an fd and own it. It will be closed on return. filename is used only
+ * for debug messages
+ */
+static int kmod_config_parse(struct kmod_config *config, int fd,
+                                                       const char *filename)
 {
        struct kmod_ctx *ctx = config->ctx;
        char *line;
        FILE *fp;
        unsigned int linenum;
+       int err;
 
-       DBG(ctx, "%s\n", filename);
-
-       fp = fopen(filename, "r");
-       if (fp == NULL)
-               return errno;
+       fp = fdopen(fd, "r");
+       if (fp == NULL) {
+               err = -errno;
+               ERR(config->ctx, "fd %d: %m", fd);
+               close(fd);
+               return err;
+       }
 
        while ((line = getline_wrapped(fp, &linenum)) != NULL) {
                char *cmd, *saveptr;
@@ -198,8 +206,8 @@ void kmod_config_free(struct kmod_config *config)
        free(config);
 }
 
-static bool conf_files_filter(struct kmod_ctx *ctx, const char *path,
-                                                       const char *fn)
+static bool conf_files_filter_out(struct kmod_ctx *ctx, const char *path,
+                                                               const char *fn)
 {
        size_t len = strlen(fn);
 
@@ -217,78 +225,84 @@ static bool conf_files_filter(struct kmod_ctx *ctx, const char *path,
        return 0;
 }
 
-static int conf_files_list(struct kmod_ctx *ctx, struct kmod_list **list,
-                                               const char *path, size_t *n)
+static DIR *conf_files_list(struct kmod_ctx *ctx, struct kmod_list **list,
+                                                       const char *path)
 {
        struct stat st;
        DIR *d;
        int err;
 
        if (stat(path, &st) < 0)
-               return -ENOENT;
+               return NULL;
 
        if (!S_ISDIR(st.st_mode)) {
-               *list = kmod_list_append(*list, (void *)path);
-               *n += 1;
-               return 0;
+               *list = kmod_list_append(*list, path);
+               return NULL;
        }
 
        d = opendir(path);
        if (d == NULL) {
                err = errno;
                ERR(ctx, "%m\n");
-               return -errno;
+               return NULL;
        }
 
        for (;;) {
                struct dirent ent, *entp;
-               char *p;
+               struct kmod_list *l, *tmp;
+               const char *dname;
 
                err = readdir_r(d, &ent, &entp);
                if (err != 0) {
-                       err = -err;
-                       goto finish;
+                       ERR(ctx, "reading entry %s\n", strerror(-err));
+                       goto fail_read;
                }
 
                if (entp == NULL)
                        break;
 
-               if (conf_files_filter(ctx, path, entp->d_name) == 1)
+               if (conf_files_filter_out(ctx, path, entp->d_name) == 1)
                        continue;
 
-               if (asprintf(&p, "%s/%s", path, entp->d_name) < 0) {
-                       err = -ENOMEM;
-                       goto finish;
+               /* insert sorted */
+               kmod_list_foreach(l, *list) {
+                       if (strcmp(entp->d_name, l->data) < 0)
+                               break;
                }
 
-               DBG(ctx, "%s\n", p);
+               dname = strdup(entp->d_name);
+               if (dname == NULL)
+                       goto fail_oom;
 
-               *list = kmod_list_append(*list, p);
-               *n += 1;
-       }
+               if (l == NULL)
+                       tmp = kmod_list_append(*list, dname);
+               else if (l == *list)
+                       tmp = kmod_list_prepend(*list, dname);
+               else
+                       tmp = kmod_list_insert_before(l, dname);
 
-finish:
-       closedir(d);
-       return err;
-}
+               if (tmp == NULL)
+                       goto fail_oom;
 
-static int base_cmp(const void *a, const void *b)
-{
-        const char *s1, *s2;
+               if (l == NULL || l == *list)
+                       *list = tmp;
+       }
 
-        s1 = *(char * const *)a;
-        s2 = *(char * const *)b;
+       return d;
 
-       return strcmp(basename(s1), basename(s2));
+fail_oom:
+       ERR(ctx, "out of memory while scanning '%s'\n", path);
+fail_read:
+       for (; *list != NULL; *list = kmod_list_remove(*list))
+               free((*list)->data);
+       closedir(d);
+       return NULL;
 }
 
 int kmod_config_new(struct kmod_ctx *ctx, struct kmod_config **p_config)
 {
        struct kmod_config *config;
-       size_t i, n = 0;
-       const char **files;
-       int err = 0;
-       struct kmod_list *list = NULL, *l;
+       size_t i;
 
        *p_config = config = calloc(1, sizeof(struct kmod_config));
        if (config == NULL)
@@ -296,33 +310,41 @@ int kmod_config_new(struct kmod_ctx *ctx, struct kmod_config **p_config)
 
        config->ctx = ctx;
 
-       for (i = 0; i < ARRAY_SIZE(config_files); i++)
-               conf_files_list(ctx, &list, config_files[i], &n);
+       for (i = 0; i < ARRAY_SIZE(config_files); i++) {
+               struct kmod_list *list = NULL;
+               DIR *d;
+               int fd;
 
-       files = malloc(sizeof(char *) * n);
-       if (files == NULL) {
-               err = -ENOMEM;
-               goto finish;
-       }
+               d = conf_files_list(ctx, &list, config_files[i]);
 
-       i = 0;
-       kmod_list_foreach(l, list) {
-               files[i] = l->data;
-               i++;
-       }
+               /* there's no entry */
+               if (list == NULL)
+                       continue;
 
-       qsort(files, n, sizeof(char *), base_cmp);
+               /* there's only one entry, and it's a file */
+               if (d == NULL) {
+                       DBG(ctx, "parsing file '%s'\n", config_files[i]);
+                       list = kmod_list_remove(list);
+                       fd = open(config_files[i], O_RDONLY);
+                       if (fd >= 0)
+                               kmod_config_parse(config, fd, config_files[i]);
 
-       for (i = 0; i < n; i++)
-               kmod_config_parse(config, files[i]);
+                       continue;
+               }
+
+               /* treat all the entries in that dir */
+               for (; list != NULL; list = kmod_list_remove(list)) {
+                       DBG(ctx, "parsing file '%s/%s'\n", config_files[i],
+                                                       (char *) list->data);
+                       fd = openat(dirfd(d), list->data, O_RDONLY);
+                       if (fd >= 0)
+                               kmod_config_parse(config, fd, list->data);
 
-finish:
-       free(files);
+                       free(list->data);
+               }
 
-       while (list) {
-               free(list->data);
-               list = kmod_list_remove(list);
+               closedir(d);
        }
 
-       return err;
+       return 0;
 }