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-rw-r--r--src/input_curl.c118
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;