[PATCH 1/3] http: offer to cast `size_t` to `curl_off_t` safely

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

This commit moves the `xcurl_off_t()` function, which validates that a
given value fits within the `curl_off_t` data type and then casts it, to
a more central place so that it can be used outside of `remote-curl.c`,
too.

At the same time, this function is renamed to conform better with the
naming convention of the helper functions that safely cast from one data
type to another which has been well established in `git-compat-util.h`.

With this move, the error message can unfortunately no longer be renamed
because the `_(...)` function is not available at the time of
definition.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 http.h        | 10 ++++++++++
 remote-curl.c | 14 +++-----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/http.h b/http.h
index 36202139f4..0a36dbd294 100644
--- a/http.h
+++ b/http.h
@@ -8,6 +8,7 @@ struct packed_git;
 #include <curl/curl.h>
 #include <curl/easy.h>
 
+#include "gettext.h"
 #include "strbuf.h"
 #include "remote.h"
 
@@ -95,6 +96,15 @@ static inline int missing__target(int code, int result)
 
 #define missing_target(a) missing__target((a)->http_code, (a)->curl_result)
 
+static inline curl_off_t cast_size_t_to_curl_off_t(size_t a)
+{
+	uintmax_t size = a;
+	if (size > maximum_signed_value_of_type(curl_off_t))
+		die(_("number too large to represent as curl_off_t "
+		      "on this platform: %"PRIuMAX), (uintmax_t)a);
+	return (curl_off_t)a;
+}
+
 /*
  * Normalize curl results to handle CURL_FAILONERROR (or lack thereof). Failing
  * http codes have their "result" converted to CURLE_HTTP_RETURNED_ERROR, and
diff --git a/remote-curl.c b/remote-curl.c
index 84f4694780..69f919454a 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -894,14 +894,6 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
 	return err;
 }
 
-static curl_off_t xcurl_off_t(size_t len)
-{
-	uintmax_t size = len;
-	if (size > maximum_signed_value_of_type(curl_off_t))
-		die(_("cannot handle pushes this big"));
-	return (curl_off_t)size;
-}
-
 /*
  * If flush_received is true, do not attempt to read any more; just use what's
  * in rpc->buf.
@@ -999,7 +991,7 @@ retry:
 		 * and we just need to send it.
 		 */
 		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, gzip_body);
-		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(gzip_size));
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, cast_size_t_to_curl_off_t(gzip_size));
 
 	} else if (use_gzip && 1024 < rpc->len) {
 		/* The client backend isn't giving us compressed data so
@@ -1030,7 +1022,7 @@ 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_LARGE, xcurl_off_t(gzip_size));
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, cast_size_t_to_curl_off_t(gzip_size));
 
 		if (options.verbosity > 1) {
 			fprintf(stderr, "POST %s (gzip %lu to %lu bytes)\n",
@@ -1043,7 +1035,7 @@ retry:
 		 * more normal Content-Length approach.
 		 */
 		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, rpc->buf);
-		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(rpc->len));
+		curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, cast_size_t_to_curl_off_t(rpc->len));
 		if (options.verbosity > 1) {
 			fprintf(stderr, "POST %s (%lu bytes)\n",
 				rpc->service_name, (unsigned long)rpc->len);
-- 
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