Windows: Update the mirror script to generate hashes and use mirror fallback

This fixes the mirror script so it correctly queries haskell.org and if
packages aren't found check repo.msys2.org.

Also the mirror functionality now generates the md5 hashes after a
mirror fetch that can be placed in the md5sums file.

Test Plan:
 mk/get-win32-tarballs.sh fetch mirror

 and ./validate

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D4118

mk/get-win32-tarballs.sh

@@ -22,11 +22,11 @@ download_file() {
 
     if ! test -f "${dest_file}"
     then
-        local curl_cmd="curl -L ${file_url} -o ${dest_file} --create-dirs -# ${extra_curl_opts}"
+        local curl_cmd="curl -f -L ${file_url} -o ${dest_file} --create-dirs -# ${extra_curl_opts}"
         if test -n "${backup_url}"; then
-            local curl_cmd_bnk="curl -L ${backup_url} -o ${dest_file} --create-dirs -# ${extra_curl_opts}"
+            local curl_cmd_bnk="curl -f -L ${backup_url} -o ${dest_file} --create-dirs -# ${extra_curl_opts}"
         else
-            local curl_cmd_bnk="echo 1"
+            local curl_cmd_bnk="true"
         fi
 
         if test "$download" = "0"
@@ -37,9 +37,10 @@ download_file() {
             return
         else
             echo "Downloading ${description} to ${dest_dir}..."
-            $curl_cmd || $curl_cmd_bnk || {
+            $curl_cmd || echo "Checking repo.msys2.org instead of Haskell.org..." && $curl_cmd_bnk || {
                 rm -f "${dest_file}"
                 fail "ERROR: Download failed."
+                exit 1
             }
         fi
     fi
@@ -48,10 +49,16 @@ download_file() {
     if test "$sigs" = "1" -a ! -f "$sig_file"
     then
         echo "Downloading ${description} (signature) to ${dest_dir}..."
-        local curl_cmd="curl -L ${file_url}.sig -o ${sig_file} --create-dirs -# ${extra_curl_opts}"
-        $curl_cmd || {
+        local curl_cmd="curl -f -L ${file_url}.sig -o ${sig_file} --create-dirs -# ${extra_curl_opts}"
+        if test -n "${backup_url}"; then
+            local curl_cmd_bnk="curl -f -L ${backup_url} -o ${sig_file} --create-dirs -# ${extra_curl_opts}"
+        else
+            local curl_cmd_bnk="true"
+        fi
+        $curl_cmd || echo "Checking repo.msys2.org instead of Haskell.org..." && $curl_cmd_bnk || {
                 rm -f "${dest_file}.sig"
                 fail "ERROR: Download failed."
+                exit 1
             }
     fi
 
@@ -72,6 +79,7 @@ download_mingw() {
                                        -e 's/-sources-/-/' \
                                        -e 's/-libwinpthread-git-/-winpthreads-git-/' `
         local mingw_url="${mingw_base_url_primary}/${mingw_url_tmp}"
+        local mingw_url_backup="${mingw_base_url_secondary}/${mingw_url_tmp}"
     else
         local mingw_url="${mingw_base_url_primary}/$1"
         local mingw_url_backup="${mingw_base_url_secondary}/$1"
@@ -165,6 +173,10 @@ sync_binaries_and_sources() {
     done
 }
 
+show_hashes_for_binaries() {
+    $FIND ghc-tarballs/ -iname "*.*" | xargs md5sum | grep -v "\.sig" | sed -s "s/\*//"
+}
+
 usage() {
     echo "$0 - Download GHC mingw toolchain tarballs"
     echo
@@ -175,6 +187,7 @@ usage() {
     echo "    download     download the necessary tarballs for the given architecture"
     echo "    fetch        download the necessary tarballs for the given architecture but doesn't verify their md5."
     echo "    verify       verify the existence and correctness of the necessary tarballs"
+    echo "    hash         generate md5 hashes for inclusion in win32-tarballs.md5sum"
     echo "    sync         upload packages downloaded with 'fetch mirror' to haskell.org"
     echo ""
     echo "and <arch> is one of i386, x86_64,all or mirror (which includes sources)"
@@ -199,6 +212,10 @@ case $1 in
         verify=0
         sync=1
         ;;
+    hash)
+        show_hashes_for_binaries
+        exit 1
+        ;;
     *)
         usage
         exit 1
@@ -222,6 +239,7 @@ case $2 in
         download_x86_64
         verify=0
         download_sources
+        show_hashes_for_binaries
         ;;
     *)
         if test "$sync" = "1"; then