texlive: reimplement fixHashes.sh in GNU Awk

The shell script doesn't work very well in non-GNU environments like
darwin. This provides an implementation that uses just a single GNU tool
- gawk, thus reduces number of points of failure.

pkgs/tools/typesetting/tex/texlive/UPGRADING.md

@@ -58,10 +58,9 @@ mv fixedHashes.nix fixedHashes-old.nix
 # start with empty fixedHashes
 echo '{}' > fixedHashes.nix
 
-nix-build ../../../../.. -Q --no-out-link -A texlive.scheme-full.pkgs | ./fixHashes.sh > ./fixedHashes-new.nix
+nix-build ../../../../.. -Q --no-out-link -A texlive.scheme-full.pkgs | ./fixHashes.awk > ./fixedHashes-new.nix
 
-# The script wrongly includes the nix store path to `biber`, which is a separate nixpkgs package
-grep -v -F '/nix/store/' fixedHashes-new.nix > fixedHashes.nix
+mv fixedHashes-new.nix fixedHashes.nix
 ```
 
 ### Commit changes

pkgs/tools/typesetting/tex/texlive/fixHashes.awk

@@ -0,0 +1,24 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i "gawk -f" -p gawk
+
+BEGIN {
+  print "{"
+}
+
+/-texlive-/ && !/\.bin/ {
+  if (match($0, /-texlive-([^\/]*)/, m) == 0) {
+    print "No match for \""$0"\"" > "/dev/stderr"
+    exit 1
+  }
+  cmd="nix-hash --type sha1 --base32 "$0
+  if (( cmd | getline hash ) <= 0) {
+    print "Error executing nix-hash" > "/dev/stderr"
+    exit 1
+  }
+  close(cmd)
+  printf("\"%s\"=\"%s\";\n", m[1], hash)
+}
+
+END {
+  print "}"
+}

pkgs/tools/typesetting/tex/texlive/fixHashes.sh

@@ -1,10 +0,0 @@
-#!/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 "}"
-