From bc38abb46a798fd998f6004562d495a9c9587061 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <git@lukegb.com>
Date: Sat, 3 Apr 2021 17:32:04 +0000
Subject: [PATCH] curl: add patch for curling directories using file:///

nix relies on using curl to fetch directories using the file scheme,
which got broken by the most recent curl update in
https://github.com/curl/curl/commit/1e5cec3297b143c1884fc0069afe247091122c2e
- which no longer provides a content-length for directories, but in so
doing causes *any* fetch of a directory to return "Couldn't resume
download (36)" (which is easily testable using the CLI)
---
 .../curl/curl-accept-ranges-not-on-dirs.patch | 29 +++++++++++++++++++
 pkgs/tools/networking/curl/default.nix        |  4 +++
 2 files changed, 33 insertions(+)
 create mode 100644 pkgs/tools/networking/curl/curl-accept-ranges-not-on-dirs.patch

diff --git a/pkgs/tools/networking/curl/curl-accept-ranges-not-on-dirs.patch b/pkgs/tools/networking/curl/curl-accept-ranges-not-on-dirs.patch
new file mode 100644
index 0000000000000..3423df3e75e5d
--- /dev/null
+++ b/pkgs/tools/networking/curl/curl-accept-ranges-not-on-dirs.patch
@@ -0,0 +1,29 @@
+diff -r -u curl-7.76.0-pristine/lib/file.c curl-7.76.0/lib/file.c
+--- curl-7.76.0-pristine/lib/file.c	2021-02-22 11:47:54.000000000 +0000
++++ curl-7.76.0/lib/file.c	2021-04-03 17:23:47.677582417 +0000
+@@ -419,10 +419,12 @@
+         return result;
+     }
+ 
+-    result = Curl_client_write(data, CLIENTWRITE_HEADER,
+-                               (char *)"Accept-ranges: bytes\r\n", 0);
+-    if(result)
+-      return result;
++    if(!S_ISDIR(statbuf.st_mode)) {
++      result = Curl_client_write(data, CLIENTWRITE_HEADER,
++                                 (char *)"Accept-ranges: bytes\r\n", 0);
++      if(result)
++        return result;
++    }
+ 
+     filetime = (time_t)statbuf.st_mtime;
+     result = Curl_gmtime(filetime, &buffer);
+@@ -464,7 +466,7 @@
+     data->state.resume_from += (curl_off_t)statbuf.st_size;
+   }
+ 
+-  if(data->state.resume_from <= expected_size)
++  if(data->state.resume_from <= expected_size || data->state.resume_from == 0)
+     expected_size -= data->state.resume_from;
+   else {
+     failf(data, "failed to resume file:// transfer");
diff --git a/pkgs/tools/networking/curl/default.nix b/pkgs/tools/networking/curl/default.nix
index 918abcf83b40e..b4fe492fc17cb 100644
--- a/pkgs/tools/networking/curl/default.nix
+++ b/pkgs/tools/networking/curl/default.nix
@@ -45,6 +45,10 @@ stdenv.mkDerivation rec {
     sha256 = "16n466an72fkick4j1phfg5a8p7f96vbnw80bgbr05bh6cvgx6z2";
   };
 
+  patches = [
+    ./curl-accept-ranges-not-on-dirs.patch
+  ];
+
   outputs = [ "bin" "dev" "out" "man" "devdoc" ];
   separateDebugInfo = stdenv.isLinux;