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[PATCH] Allow curl to rewind the read buffers

From
Martin Storsjö <martin@martin.st>
Date
Apr 1, 2009, 16:48 UTC
Message-ID
<Pine.LNX.4.64.0904011946510.5901@localhost.localdomain>
In-Reply-To
<7vbprg1h3m.fsf@gitster.siamese.dyndns.org>

When using multi-pass authentication methods, the curl library may need to rewind the read buffers (depending on how much already has been fed to the server) used for providing data to HTTP PUT, POST or PROPFIND, and in order to allow the library to do so, we need to tell it how by providing either an ioctl callback or a seek callback.

This patch adds an ioctl callback, which should be usable on older curl versions (since 7.12.3) than the seek callback (introduced in curl 7.18.0).

Some HTTP servers (such as Apache) give an 401 error reply immediately after receiving the headers (so no data has been read from the read buffers, and thus no rewinding is needed), but other servers (such as Lighttpd) only replies after the whole request has been sent and all data has been read from the read buffers, making rewinding necessary.

Signed-off-by: Martin Storsjo <martin@martin.st>
---
Updated comment to better describe the potential need for this.
 http-push.c |   24 ++++++++++++++++++++++++
 http.c      |   19 +++++++++++++++++++
 http.h      |    7 +++++++
 3 files changed, 50 insertions(+), 0 deletions(-)
diff --git a/http-push.c b/http-push.c
index 6ce5a1d..7dc0dd4 100644
--- a/http-push.c
+++ b/http-push.c
@@ -567,6 +567,10 @@ static void start_put(struct transfer_request *request)
 	curl_easy_setopt(slot->curl, CURLOPT_INFILE, &request->buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, request->buffer.buf.len);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &request->buffer);
+#endif
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_null);
 	curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, DAV_PUT);
 	curl_easy_setopt(slot->curl, CURLOPT_UPLOAD, 1);
@@ -1267,6 +1271,10 @@ static struct remote_lock *lock_remote(const char *path, long timeout)
 	curl_easy_setopt(slot->curl, CURLOPT_INFILE, &out_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, out_buffer.buf.len);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &out_buffer);
+#endif
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, &in_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_URL, url);
@@ -1508,6 +1516,10 @@ static void remote_ls(const char *path, int flags,
 	curl_easy_setopt(slot->curl, CURLOPT_INFILE, &out_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, out_buffer.buf.len);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &out_buffer);
+#endif
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, &in_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_URL, url);
@@ -1584,6 +1596,10 @@ static int locking_available(void)
 	curl_easy_setopt(slot->curl, CURLOPT_INFILE, &out_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, out_buffer.buf.len);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &out_buffer);
+#endif
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, &in_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_URL, repo->url);
@@ -1766,6 +1782,10 @@ static int update_remote(unsigned char *sha1, struct remote_lock *lock)
 	curl_easy_setopt(slot->curl, CURLOPT_INFILE, &out_buffer);
 	curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, out_buffer.buf.len);
 	curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+	curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &out_buffer);
+#endif
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_null);
 	curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, DAV_PUT);
 	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, dav_headers);
@@ -1910,6 +1930,10 @@ static void update_remote_info_refs(struct remote_lock *lock)
 		curl_easy_setopt(slot->curl, CURLOPT_INFILE, &buffer);
 		curl_easy_setopt(slot->curl, CURLOPT_INFILESIZE, buffer.buf.len);
 		curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, fread_buffer);
+#ifndef NO_CURL_IOCTL
+		curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
+		curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, &buffer);
+#endif
 		curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_null);
 		curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, DAV_PUT);
 		curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, dav_headers);
diff --git a/http.c b/http.c
index eae74aa..3e8d548 100644
--- a/http.c
+++ b/http.c
@@ -44,6 +44,25 @@ size_t fread_buffer(void *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 	return size;
 }
 
+#ifndef NO_CURL_IOCTL
+curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp)
+{
+	struct buffer *buffer = clientp;
+
+	switch (cmd) {
+	case CURLIOCMD_NOP:
+		return CURLIOE_OK;
+
+	case CURLIOCMD_RESTARTREAD:
+		buffer->posn = 0;
+		return CURLIOE_OK;
+
+	default:
+		return CURLIOE_UNKNOWNCMD;
+	}
+}
+#endif
+
 size_t fwrite_buffer(const void *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 {
 	size_t size = eltsize * nmemb;
diff --git a/http.h b/http.h
index 905b462..26abebe 100644
--- a/http.h
+++ b/http.h
@@ -37,6 +37,10 @@
 #define CURLE_HTTP_RETURNED_ERROR CURLE_HTTP_NOT_FOUND
 #endif
 
+#if LIBCURL_VERSION_NUM < 0x070c03
+#define NO_CURL_IOCTL
+#endif
+
 struct slot_results
 {
 	CURLcode curl_result;
@@ -67,6 +71,9 @@ struct buffer
 extern size_t fread_buffer(void *ptr, size_t eltsize, size_t nmemb, void *strbuf);
 extern size_t fwrite_buffer(const void *ptr, size_t eltsize, size_t nmemb, void *strbuf);
 extern size_t fwrite_null(const void *ptr, size_t eltsize, size_t nmemb, void *strbuf);
+#ifndef NO_CURL_IOCTL
+extern curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp);
+#endif
 
 /* Slot lifecycle functions */
 extern struct active_request_slot *get_active_slot(void);

-- 
1.6.0.2
Previous: Martin StorsjöNext: Junio C Hamano
Message 4 of 5 in “Allow curl to rewind the read buffers”
  1. Allow curl to rewind the read buffersMartin Storsjö, Apr 1, 2009
  2. Junio C HamanoApr 1, 2009
  3. Martin StorsjöApr 1, 2009
  4. Allow curl to rewind the read buffersMartin Storsjö, Apr 1, 2009
  5. Junio C HamanoApr 2, 2009

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