From 738bae4ec2a73c16fa8d4f76b0a41474937a366c Mon Sep 17 00:00:00 2001
From: Uli Baum <xeji@cat3.de>
Date: Mon, 27 Aug 2018 14:04:43 +0200
Subject: [PATCH] texlive: make packages fixed-output derivations

This reverts a part of the changes made in #40826.
Fixed-output derivations save time and space on rebuilds.
---
 .../tools/typesetting/tex/texlive/default.nix | 35 ++++++++++++++++---
 .../typesetting/tex/texlive/fixHashes.sh      | 10 ++++++
 2 files changed, 40 insertions(+), 5 deletions(-)
 create mode 100755 pkgs/tools/typesetting/tex/texlive/fixHashes.sh

diff --git a/pkgs/tools/typesetting/tex/texlive/default.nix b/pkgs/tools/typesetting/tex/texlive/default.nix
index e4799e39c43..c10b9c99296 100644
--- a/pkgs/tools/typesetting/tex/texlive/default.nix
+++ b/pkgs/tools/typesetting/tex/texlive/default.nix
@@ -29,6 +29,7 @@
 { stdenv, lib, fetchurl, runCommand, writeText, buildEnv
 , callPackage, ghostscriptX, harfbuzz, poppler_min
 , makeWrapper, python, ruby, perl
+, useFixedHashes ? true
 , recurseIntoAttrs
 }:
 let
@@ -41,6 +42,10 @@ let
     };
   };
 
+  # map: name -> fixed-output hash
+  # sha1 in base32 was chosen as a compromise between security and length
+  fixedHashes = lib.optionalAttrs useFixedHashes (import ./fixedHashes.nix);
+
   # function for creating a working environment from a set of TL packages
   combine = import ./combine.nix {
     inherit bin combinePkgs buildEnv fastUnique lib makeWrapper writeText
@@ -116,6 +121,7 @@ let
       # the basename used by upstream (without ".tar.xz" suffix)
       urlName = pname + lib.optionalString (tlType != "run") ".${tlType}";
       tlName = urlName + "-${version}";
+      fixedHash = fixedHashes.${tlName} or null; # be graceful about missing hashes
 
       urls = args.urls or (if args ? url then [ args.url ] else
               map (up: "${up}/${urlName}.tar.xz") urlPrefixes
@@ -155,11 +161,30 @@ let
           -C "$out" --anchored --exclude=tlpkg --keep-old-files
       '' + postUnpack;
 
-    in runCommand "texlive-${tlName}" {
-        # lots of derivations, not meant to be cached
-        preferLocalBuild = true; allowSubstitutes = false;
-        inherit passthru;
-      }
+    in if sha512 == "" then
+      # hash stripped from pkgs.nix to save space -> fetch&unpack in a single step
+      fetchurl {
+        inherit urls;
+        sha1 = if fixedHash == null then throw "TeX Live package ${tlName} is missing hash!"
+          else fixedHash;
+        name = tlName;
+        recursiveHash = true;
+        downloadToTemp = true;
+        postFetch = ''mkdir "$out";'' + unpackCmd "$downloadedFile";
+        # TODO: perhaps override preferHashedMirrors and allowSubstitutes
+     }
+        // passthru
+
+    else runCommand "texlive-${tlName}"
+      ( { # lots of derivations, not meant to be cached
+          preferLocalBuild = true; allowSubstitutes = false;
+          inherit passthru;
+        } // lib.optionalAttrs (fixedHash != null) {
+          outputHash = fixedHash;
+          outputHashAlgo = "sha1";
+          outputHashMode = "recursive";
+        }
+      )
       ( ''
           mkdir "$out"
         '' + unpackCmd "'${src}'"
diff --git a/pkgs/tools/typesetting/tex/texlive/fixHashes.sh b/pkgs/tools/typesetting/tex/texlive/fixHashes.sh
new file mode 100755
index 00000000000..439660682e2
--- /dev/null
+++ b/pkgs/tools/typesetting/tex/texlive/fixHashes.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+echo "{"
+grep -v -F '.bin-' | while read path; do
+    hash=`nix-hash --type sha1 --base32 "$path"`
+    echo -n "$path" | sed -E 's/[^-]*-texlive-(.*)/"\1"/'
+    echo "=\"$hash\";"
+done
+echo "}"
+