rules: let empty strings added to buffer always return offset 0

diff --git a/udev/udev-rules.c b/udev/udev-rules.c
index 22fb2c3857729f4d64b0b1b40f512d9e80fc10fc..535ec3f141975b6adbb9b353fbe07215c31f67f1 100644 (file)
--- a/udev/udev-rules.c
+++ b/udev/udev-rules.c
@@ -205,6 +205,11 @@ static int add_string(struct udev_rules *rules, const char *str)
        size_t len = strlen(str)+1;
        int off;
 
+       /* offset 0 is always '\0' */
+       if (str[0] == '\0')
+               return 0;
+
+       /* grow buffer if needed */
        if (rules->buf_cur + len+1 >= rules->buf_max) {
                char *buf;
                unsigned int add;
@@ -212,7 +217,7 @@ static int add_string(struct udev_rules *rules, const char *str)
                /* double the buffer size */
                add = rules->buf_max;
                if (add < len)
-                       add = len;
+                       add = len * 2;
 
                buf = realloc(rules->buf, rules->buf_max + add);
                if (buf == NULL)
@@ -231,6 +236,7 @@ static int add_string(struct udev_rules *rules, const char *str)
 static int add_token(struct udev_rules *rules, struct token *token)
 {
 
+       /* grow buffer if needed */
        if (rules->token_cur+1 >= rules->token_max) {
                struct token *tokens;
                unsigned int add;
@@ -238,7 +244,7 @@ static int add_token(struct udev_rules *rules, struct token *token)
                /* double the buffer size */
                add = rules->token_max;
                if (add < 1)
-                       add = 1;
+                       add = 2;
 
                tokens = realloc(rules->tokens, (rules->token_max + add ) * sizeof(struct token));
                if (tokens == NULL)
@@ -1388,15 +1394,18 @@ struct udev_rules *udev_rules_new(struct udev *udev, int resolve_names)
 
        /* init token array and string buffer */
        rules->tokens = malloc(PREALLOC_TOKEN * sizeof(struct token));
-       if (rules->tokens != NULL)
-               rules->token_max = PREALLOC_TOKEN;
+       if (rules->tokens == NULL)
+               return NULL;
+       rules->token_max = PREALLOC_TOKEN;
        rules->buf = malloc(PREALLOC_STRBUF);
-       if (rules->buf != NULL)
-               rules->buf_max = PREALLOC_STRBUF;
+       if (rules->buf == NULL)
+               return NULL;
+       rules->buf_max = PREALLOC_STRBUF;
+       /* offset 0 is always '\0' */
+       rules->buf[0] = '\0';
+       rules->buf_cur = 1;
        info(udev, "prealloc %zu bytes tokens (%u * %zu bytes), %zu bytes buffer\n",
             rules->token_max * sizeof(struct token), rules->token_max, sizeof(struct token), rules->buf_max);
-       /* offset 0 in the string buffer is always empty */
-       add_string(rules, "");
 
        if (udev_get_rules_path(udev) != NULL) {
                /* custom rules location for testing */
@@ -1593,14 +1602,15 @@ enum escape_type {
 
 int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event)
 {
-       struct token *rule;
        struct token *cur;
+       struct token *rule;
 
        if (rules->tokens == NULL)
                return -1;
 
        /* loop through token list, match, run actions or forward to next rule */
        cur = &rules->tokens[0];
+       rule = cur;
        while (cur != NULL && cur->type != TK_END) {
                enum escape_type esc = ESCAPE_UNSET;
                unsigned int idx;