diff options
| -rw-r--r-- | src/input_curl.c | 118 |
1 files changed, 115 insertions, 3 deletions
diff --git a/src/input_curl.c b/src/input_curl.c index 11473eab0..7a6875ff8 100644 --- a/src/input_curl.c +++ b/src/input_curl.c @@ -29,6 +29,9 @@ #include <curl/curl.h> #include <glib.h> +/** rewinding is possible after up to 64 kB */ +static const off_t max_rewind_size = 64 * 1024; + /** * Buffers created by input_curl_writefunction(). */ @@ -64,6 +67,9 @@ struct input_curl { /** did libcurl tell us the we're at the end of the response body? */ bool eof; + + /** limited list of old buffers, for rewinding */ + struct list_head rewind; }; /** libcurl should accept "ICY 200 OK" */ @@ -111,6 +117,13 @@ input_curl_easy_free(struct input_curl *c) g_free(buffer); } + + while (!list_empty(&c->rewind)) { + struct buffer *buffer = (struct buffer *)c->rewind.next; + list_del(&buffer->siblings); + + g_free(buffer); + } } /** @@ -169,7 +182,8 @@ input_curl_select(struct input_curl *c) } static size_t -read_from_buffer(struct buffer *buffer, void *dest, size_t length) +read_from_buffer(struct buffer *buffer, void *dest, size_t length, + struct list_head *rewind_head) { assert(buffer->size > 0); assert(buffer->consumed < buffer->size); @@ -182,7 +196,12 @@ read_from_buffer(struct buffer *buffer, void *dest, size_t length) buffer->consumed += length; if (buffer->consumed == buffer->size) { list_del(&buffer->siblings); - g_free(buffer); + + if (rewind_head != NULL) + /* append this buffer to the rewind buffer list */ + list_add_tail(&buffer->siblings, rewind_head); + else + g_free(buffer); } return length; @@ -193,6 +212,7 @@ input_curl_read(struct input_stream *is, void *ptr, size_t size) { struct input_curl *c = is->data; CURLMcode mcode = CURLM_CALL_MULTI_PERFORM; + struct list_head *rewind_head; size_t nbytes = 0; char *dest = ptr; @@ -223,15 +243,37 @@ input_curl_read(struct input_stream *is, void *ptr, size_t size) /* send buffer contents */ + if (!list_empty(&c->rewind) || is->offset == 0) + /* at the beginning or already writing the rewind + buffer list */ + rewind_head = &c->rewind; + else + /* we don't need the rewind buffers anymore */ + rewind_head = NULL; + while (size > 0 && !list_empty(&c->buffers)) { struct buffer *buffer = (struct buffer *)c->buffers.next; - size_t copy = read_from_buffer(buffer, dest + nbytes, size); + size_t copy = read_from_buffer(buffer, dest + nbytes, size, + rewind_head); nbytes += copy; size -= copy; } is->offset += (off_t)nbytes; + + if (rewind_head != NULL && is->offset > max_rewind_size) { + /* drop the rewind buffer, it has grown too large */ + + while (!list_empty(&c->rewind)) { + struct buffer *buffer = + (struct buffer *)c->rewind.next; + list_del(&buffer->siblings); + + g_free(buffer); + } + } + return nbytes; } @@ -414,11 +456,80 @@ input_curl_send_request(struct input_curl *c) } static bool +input_curl_can_rewind(struct input_stream *is) +{ + struct input_curl *c = is->data; + struct buffer *buffer; + + if (!list_empty(&c->rewind)) + /* the rewind buffer hasn't been wiped yet */ + return true; + + if (list_empty(&c->buffers)) + /* there are no buffers at all - cheap rewind not + possible */ + return false; + + /* rewind is possible if this is the very first buffer of the + resource */ + buffer = (struct buffer*)c->buffers.next; + return (off_t)buffer->consumed == is->offset; +} + +static void +input_curl_rewind(struct input_stream *is) +{ + struct input_curl *c = is->data; + struct buffer *buffer; +#ifndef NDEBUG + off_t offset = 0; +#endif + + /* reset all rewind buffers */ + + list_for_each_entry(buffer, &c->rewind, siblings) { +#ifndef NDEBUG + offset += buffer->consumed; +#endif + buffer->consumed = 0; + } + + /* rewind the current buffer */ + + if (!list_empty(&c->buffers)) { + buffer = (struct buffer*)c->buffers.next; +#ifndef NDEBUG + offset += buffer->consumed; +#endif + buffer->consumed = 0; + } + + assert(offset == is->offset); + + /* move all rewind buffers back to the regular buffer list */ + + list_splice_init(&c->rewind, &c->buffers); + is->offset = 0; +} + +static bool input_curl_seek(struct input_stream *is, off_t offset, int whence) { struct input_curl *c = is->data; bool ret; + if (whence == SEEK_SET && offset == 0) { + if (is->offset == 0) + /* no-op */ + return true; + + if (input_curl_can_rewind(is)) { + /* we have enough rewind buffers left */ + input_curl_rewind(is); + return true; + } + } + if (!is->seekable) return false; @@ -478,6 +589,7 @@ input_curl_open(struct input_stream *is, const char *url) c = g_new0(struct input_curl, 1); c->url = g_strdup(url); INIT_LIST_HEAD(&c->buffers); + INIT_LIST_HEAD(&c->rewind); is->data = c; |