diff options
| -rw-r--r-- | content/fetchers/fetch_data.c | 114 |
1 files changed, 78 insertions, 36 deletions
diff --git a/content/fetchers/fetch_data.c b/content/fetchers/fetch_data.c index 60ccf13f4..2f0141232 100644 --- a/content/fetchers/fetch_data.c +++ b/content/fetchers/fetch_data.c @@ -51,7 +51,9 @@ struct fetch_data_context { char *data; size_t datalen; bool base64; - bool senttype; + + bool aborted; + bool locked; struct fetch_data_context *r_next, *r_prev; }; @@ -84,9 +86,7 @@ static void *fetch_data_setup(struct fetch *parent_fetch, const char *url, if (ctx == NULL) return NULL; - - RING_INSERT(ring, ctx); - + ctx->parent_fetch = parent_fetch; ctx->url = strdup(url); @@ -94,6 +94,8 @@ static void *fetch_data_setup(struct fetch *parent_fetch, const char *url, free(ctx); return NULL; } + + RING_INSERT(ring, ctx); return ctx; } @@ -117,8 +119,21 @@ static void fetch_data_free(void *ctx) static void fetch_data_abort(void *ctx) { struct fetch_data_context *c = ctx; - fetch_remove_from_queues(c->parent_fetch); - fetch_data_free(ctx); + + /* To avoid the poll loop having to deal with the fetch context + * disappearing from under it, we simply flag the abort here. + * The poll loop itself will perform the appropriate cleanup. + */ + c->aborted = true; +} + +static void fetch_data_send_callback(fetch_msg msg, + struct fetch_data_context *c, const void *data, + unsigned long size) +{ + c->locked = true; + fetch_send_callback(msg, c->parent_fetch, data, size); + c->locked = false; } static bool fetch_data_process(struct fetch_data_context *c) @@ -137,7 +152,7 @@ static bool fetch_data_process(struct fetch_data_context *c) if (strlen(c->url) < 6) { /* 6 is the minimum possible length (data:,) */ - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + fetch_data_send_callback(FETCH_ERROR, c, "Malformed data: URL", 0); return false; } @@ -147,7 +162,7 @@ static bool fetch_data_process(struct fetch_data_context *c) /* find the comma */ if ( (comma = strchr(params, ',')) == NULL) { - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + fetch_data_send_callback(FETCH_ERROR, c, "Malformed data: URL", 0); return false; } @@ -161,7 +176,7 @@ static bool fetch_data_process(struct fetch_data_context *c) } if (c->mimetype == NULL) { - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + fetch_data_send_callback(FETCH_ERROR, c, "Unable to allocate memory for mimetype in data: URL", 0); return false; @@ -179,7 +194,7 @@ static bool fetch_data_process(struct fetch_data_context *c) */ unescaped = curl_easy_unescape(curl, comma + 1, 0, (int *)&c->datalen); if (unescaped == NULL) { - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + fetch_data_send_callback(FETCH_ERROR, c, "Unable to URL decode data: URL", 0); return false; } @@ -187,8 +202,8 @@ static bool fetch_data_process(struct fetch_data_context *c) if (c->base64) { c->data = malloc(c->datalen); /* safe: always gets smaller */ if (base64_decode(unescaped, c->datalen, c->data, - &(c->datalen)) == false) { - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + &(c->datalen)) == false) { + fetch_data_send_callback(FETCH_ERROR, c, "Unable to Base64 decode data: URL", 0); curl_free(unescaped); return false; @@ -196,7 +211,7 @@ static bool fetch_data_process(struct fetch_data_context *c) } else { c->data = malloc(c->datalen); if (c->data == NULL) { - fetch_send_callback(FETCH_ERROR, c->parent_fetch, + fetch_data_send_callback(FETCH_ERROR, c, "Unable to allocate memory for data: URL", 0); curl_free(unescaped); return false; @@ -211,7 +226,7 @@ static bool fetch_data_process(struct fetch_data_context *c) static void fetch_data_poll(const char *scheme) { - struct fetch_data_context *c; + struct fetch_data_context *c, *next; struct cache_data cachedata; if (ring == NULL) return; @@ -225,32 +240,59 @@ static void fetch_data_poll(const char *scheme) cachedata.no_cache = true; cachedata.etag = NULL; cachedata.last_modified = 0; - - while ((c = ring)) { - if (c->senttype == true || fetch_data_process(c) == true) { - if (c->senttype == false) { - fetch_set_http_code(c->parent_fetch, 200); - LOG(("setting data: MIME type to %s, length to %d", - c->mimetype, c->datalen)); - c->senttype = true; - fetch_send_callback(FETCH_TYPE, - c->parent_fetch, - c->mimetype, c->datalen); - continue; - } else { - fetch_send_callback(FETCH_DATA, - c->parent_fetch, - c->data, c->datalen); - fetch_send_callback(FETCH_FINISHED, - c->parent_fetch, - &cachedata, 0); - fetch_remove_from_queues(c->parent_fetch); - fetch_free(c->parent_fetch); + + /* Iterate over ring, processing each pending fetch */ + c = ring; + do { + /* Take a copy of the next pointer as we may destroy + * the ring item we're currently processing */ + next = c->r_next; + + /* Ignore fetches that have been flagged as locked. + * This allows safe re-entrant calls to this function. + * Re-entrancy can occur if, as a result of a callback, + * the interested party causes fetch_poll() to be called + * again. + */ + if (c->locked == true) { + continue; + } + + /* Only process non-aborted fetches */ + if (!c->aborted && fetch_data_process(c) == true) { + fetch_set_http_code(c->parent_fetch, 200); + LOG(("setting data: MIME type to %s, length to %d", + c->mimetype, c->datalen)); + /* Any callback can result in the fetch being aborted. + * Therefore, we _must_ check for this after _every_ + * call to fetch_data_send_callback(). + */ + fetch_data_send_callback(FETCH_TYPE, + c, c->mimetype, c->datalen); + if (!c->aborted) { + fetch_data_send_callback(FETCH_DATA, + c, c->data, c->datalen); + } + if (!c->aborted) { + fetch_data_send_callback(FETCH_FINISHED, + c, &cachedata, 0); } } else { LOG(("Processing of %s failed!", c->url)); + + /* Ensure that we're unlocked here. If we aren't, + * then fetch_data_process() is broken. + */ + assert(c->locked == false); } - } + + fetch_remove_from_queues(c->parent_fetch); + fetch_free(c->parent_fetch); + + /* Advance to next ring entry, exiting if we've reached + * the start of the ring or the ring has become empty + */ + } while ( (c = next) != ring && ring != NULL); } void fetch_data_register(void) |