http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION

The IOCTLFUNCTION option has been deprecated, and generates a compiler
warning in recent versions of curl. We can switch to using SEEKFUNCTION
instead. It was added in 2008 via curl 7.18.0; our INSTALL file already
indicates we require at least curl 7.19.4.

But there's one catch: curl says we should use CURL_SEEKFUNC_{OK,FAIL},
and those didn't arrive until 7.19.5. One workaround would be to use a
bare 0/1 here (or define our own macros).  But let's just bump the
minimum required version to 7.19.5. That version is only a minor version
bump from our existing requirement, and is only a 2 month time bump for
versions that are almost 13 years old. So it's not likely that anybody
cares about the distinction.

Switching means we have to rewrite the ioctl functions into seek
functions. In some ways they are simpler (seeking is the only
operation), but in some ways more complex (the ioctl allowed only a full
rewind, but now we can seek to arbitrary offsets).

Curl will only ever use SEEK_SET (per their documentation), so I didn't
bother implementing anything else, since it would naturally be
completely untested. This seems unlikely to change, but I added an
assertion just in case.

Likewise, I doubt curl will ever try to seek outside of the buffer sizes
we've told it, but I erred on the defensive side here, rather than do an
out-of-bounds read.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

diff --git a/INSTALL b/INSTALL
index 8474ad01bf9db87ec293bd6d5cd2ed7706c56914..88c8b3cd465cce2b3827d1e3e8938d24c9beff0c 100644 (file)
--- a/INSTALL
+++ b/INSTALL
@@ -145,6 +145,10 @@ Issues of note:
          patches into an IMAP mailbox, you do not have to have them
          (use NO_CURL).
 
+         Git requires version "7.19.5" or later of "libcurl" to build
+         without NO_CURL. This version requirement may be bumped in
+         the future.
+
        - "expat" library; git-http-push uses it for remote lock
          management over DAV.  Similar to "curl" above, this is optional
          (with NO_EXPAT).

diff --git a/http-push.c b/http-push.c
index 585fbd57e34ed2beefef3fd8a724119f7c6eda7c..756779bb195bde236d84f87b81ca9f93a9b7bf68 100644 (file)
--- a/http-push.c
+++ b/http-push.c
@@ -203,9 +203,9 @@ static void curl_setup_http(CURL *curl, const char *url,
        curl_easy_setopt(curl, CURLOPT_INFILE, buffer);
        curl_easy_setopt(curl, CURLOPT_INFILESIZE, buffer->buf.len);
        curl_easy_setopt(curl, CURLOPT_READFUNCTION, fread_buffer);
-#ifndef NO_CURL_IOCTL
-       curl_easy_setopt(curl, CURLOPT_IOCTLFUNCTION, ioctl_buffer);
-       curl_easy_setopt(curl, CURLOPT_IOCTLDATA, buffer);
+#ifndef NO_CURL_SEEK
+       curl_easy_setopt(curl, CURLOPT_SEEKFUNCTION, seek_buffer);
+       curl_easy_setopt(curl, CURLOPT_SEEKDATA, buffer);
 #endif
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_fn);
        curl_easy_setopt(curl, CURLOPT_NOBODY, 0);

diff --git a/http.c b/http.c
index 8b23a546afdf40dc9f15756f637a62286fe1bdd0..b228137388e66e6b35dfdac35bd6c9dbdd553b3d 100644 (file)
--- a/http.c
+++ b/http.c
@@ -186,22 +186,20 @@ size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
        return size / eltsize;
 }
 
-#ifndef NO_CURL_IOCTL
-curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp)
+#ifndef NO_CURL_SEEK
+int seek_buffer(void *clientp, curl_off_t offset, int origin)
 {
        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;
+       if (origin != SEEK_SET)
+               BUG("seek_buffer only handles SEEK_SET");
+       if (offset < 0 || offset >= buffer->buf.len) {
+               error("curl seek would be outside of buffer");
+               return CURL_SEEKFUNC_FAIL;
        }
+
+       buffer->posn = offset;
+       return CURL_SEEKFUNC_OK;
 }
 #endif
 

diff --git a/http.h b/http.h
index 5de792ef3fe1dd8597c9b890a120eeacd2eb4994..90679e141040324929ae15da742b800753348764 100644 (file)
--- a/http.h
+++ b/http.h
@@ -41,8 +41,8 @@
 #define CURLE_HTTP_RETURNED_ERROR CURLE_HTTP_NOT_FOUND
 #endif
 
-#if LIBCURL_VERSION_NUM < 0x070c03
-#define NO_CURL_IOCTL
+#if LIBCURL_VERSION_NUM < 0x071200
+#define NO_CURL_SEEK
 #endif
 
 /*
@@ -82,8 +82,8 @@ struct buffer {
 size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
 size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
 size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf);
-#ifndef NO_CURL_IOCTL
-curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp);
+#ifndef NO_CURL_SEEK
+int seek_buffer(void *clientp, curl_off_t offset, int origin);
 #endif
 
 /* Slot lifecycle functions */

diff --git a/remote-curl.c b/remote-curl.c
index 0290b04891596bd4ebed0154c25b0713acd30d08..f50531624a9e3a1469b9bb1b12d531227d19dcc3 100644 (file)
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -707,26 +707,24 @@ static size_t rpc_out(void *ptr, size_t eltsize,
        return avail;
 }
 
-#ifndef NO_CURL_IOCTL
-static curlioerr rpc_ioctl(CURL *handle, int cmd, void *clientp)
+#ifndef NO_CURL_SEEK
+static int rpc_seek(void *clientp, curl_off_t offset, int origin)
 {
        struct rpc_state *rpc = clientp;
 
-       switch (cmd) {
-       case CURLIOCMD_NOP:
-               return CURLIOE_OK;
+       if (origin != SEEK_SET)
+               BUG("rpc_seek only handles SEEK_SET, not %d", origin);
 
-       case CURLIOCMD_RESTARTREAD:
-               if (rpc->initial_buffer) {
-                       rpc->pos = 0;
-                       return CURLIOE_OK;
+       if (rpc->initial_buffer) {
+               if (offset < 0 || offset > rpc->len) {
+                       error("curl seek would be outside of rpc buffer");
+                       return CURL_SEEKFUNC_FAIL;
                }
-               error(_("unable to rewind rpc post data - try increasing http.postBuffer"));
-               return CURLIOE_FAILRESTART;
-
-       default:
-               return CURLIOE_UNKNOWNCMD;
+               rpc->pos = offset;
+               return CURL_SEEKFUNC_OK;
        }
+       error(_("unable to rewind rpc post data - try increasing http.postBuffer"));
+       return CURL_SEEKFUNC_FAIL;
 }
 #endif
 
@@ -947,9 +945,9 @@ retry:
                rpc->initial_buffer = 1;
                curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, rpc_out);
                curl_easy_setopt(slot->curl, CURLOPT_INFILE, rpc);
-#ifndef NO_CURL_IOCTL
-               curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, rpc_ioctl);
-               curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, rpc);
+#ifndef NO_CURL_SEEK
+               curl_easy_setopt(slot->curl, CURLOPT_SEEKFUNCTION, rpc_seek);
+               curl_easy_setopt(slot->curl, CURLOPT_SEEKDATA, rpc);
 #endif
                if (options.verbosity > 1) {
                        fprintf(stderr, "POST %s (chunked)\n", rpc->service_name);