http.postbuffer: allow full range of ssize_t values

Unfortunately, in order to push some large repos where a server does
not support chunked encoding, the http postbuffer must sometimes
exceed two gigabytes.  On a 64-bit system, this is OK: we just malloc
a larger buffer.

This means that we need to use CURLOPT_POSTFIELDSIZE_LARGE to set the
buffer size.

Signed-off-by: David Turner <dturner@twosigma.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1901,6 +1901,7 @@ extern int git_parse_maybe_bool(const char *);
 extern int git_config_int(const char *, const char *);
 extern int64_t git_config_int64(const char *, const char *);
 extern unsigned long git_config_ulong(const char *, const char *);
+extern ssize_t git_config_ssize_t(const char *, const char *);
 extern int git_config_bool_or_int(const char *, const char *, int *);
 extern int git_config_bool(const char *, const char *);
 extern int git_config_maybe_bool(const char *, const char *);

config.c

@@ -834,6 +834,15 @@ int git_parse_ulong(const char *value, unsigned long *ret)
 	return 1;
 }
 
+static int git_parse_ssize_t(const char *value, ssize_t *ret)
+{
+	intmax_t tmp;
+	if (!git_parse_signed(value, &tmp, maximum_signed_value_of_type(ssize_t)))
+		return 0;
+	*ret = tmp;
+	return 1;
+}
+
 NORETURN
 static void die_bad_number(const char *name, const char *value)
 {
@@ -892,6 +901,14 @@ unsigned long git_config_ulong(const char *name, const char *value)
 	return ret;
 }
 
+ssize_t git_config_ssize_t(const char *name, const char *value)
+{
+	ssize_t ret;
+	if (!git_parse_ssize_t(value, &ret))
+		die_bad_number(name, value);
+	return ret;
+}
+
 int git_parse_maybe_bool(const char *value)
 {
 	if (!value)

http.c

@@ -19,7 +19,7 @@ long int git_curl_ipresolve;
 #endif
 int active_requests;
 int http_is_verbose;
-size_t http_post_buffer = 16 * LARGE_PACKET_MAX;
+ssize_t http_post_buffer = 16 * LARGE_PACKET_MAX;
 
 #if LIBCURL_VERSION_NUM >= 0x070a06
 #define LIBCURL_CAN_HANDLE_AUTH_ANY
@@ -331,7 +331,9 @@ static int http_options(const char *var, const char *value, void *cb)
 	}
 
 	if (!strcmp("http.postbuffer", var)) {
-		http_post_buffer = git_config_int(var, value);
+		http_post_buffer = git_config_ssize_t(var, value);
+		if (http_post_buffer < 0)
+			warning(_("negative value for http.postbuffer; defaulting to %d"), LARGE_PACKET_MAX);
 		if (http_post_buffer < LARGE_PACKET_MAX)
 			http_post_buffer = LARGE_PACKET_MAX;
 		return 0;

http.h

@@ -111,7 +111,7 @@ extern struct curl_slist *http_copy_default_headers(void);
 extern long int git_curl_ipresolve;
 extern int active_requests;
 extern int http_is_verbose;
-extern size_t http_post_buffer;
+extern ssize_t http_post_buffer;
 extern struct credential http_auth;
 
 extern char curl_errorstr[CURL_ERROR_SIZE];

remote-curl.c

@@ -531,6 +531,12 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
 	return err;
 }
 
+static curl_off_t xcurl_off_t(ssize_t len) {
+	if (len > maximum_signed_value_of_type(curl_off_t))
+		die("cannot handle pushes this big");
+	return (curl_off_t) len;
+}
+
 static int post_rpc(struct rpc_state *rpc)
 {
 	struct active_request_slot *slot;
@@ -614,7 +620,7 @@ retry:
 		 * and we just need to send it.
 		 */
 		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, gzip_body);
-		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE, gzip_size);
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(gzip_size));
 
 	} else if (use_gzip && 1024 < rpc->len) {
 		/* The client backend isn't giving us compressed data so
@@ -645,7 +651,7 @@ retry:
 
 		headers = curl_slist_append(headers, "Content-Encoding: gzip");
 		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, gzip_body);
-		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE, gzip_size);
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(gzip_size));
 
 		if (options.verbosity > 1) {
 			fprintf(stderr, "POST %s (gzip %lu to %lu bytes)\n",
@@ -658,7 +664,7 @@ retry:
 		 * more normal Content-Length approach.
 		 */
 		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, rpc->buf);
-		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE, rpc->len);
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(rpc->len));
 		if (options.verbosity > 1) {
 			fprintf(stderr, "POST %s (%lu bytes)\n",
 				rpc->service_name, (unsigned long)rpc->len);