From 830f9fabd4a564bfbc3fbfc33a62b02010c0a7a5 Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Thu, 27 Sep 2018 17:40:16 -0500
Subject: [PATCH 1/3] patch-shebangs: use isScript to safely check for shebang
 start

Fixes commonly encountered errors about broken pipes or null-bytes in
command-substitution.
---
 pkgs/build-support/setup-hooks/patch-shebangs.sh | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/pkgs/build-support/setup-hooks/patch-shebangs.sh b/pkgs/build-support/setup-hooks/patch-shebangs.sh
index d5586fccae6..0ac81102658 100644
--- a/pkgs/build-support/setup-hooks/patch-shebangs.sh
+++ b/pkgs/build-support/setup-hooks/patch-shebangs.sh
@@ -19,9 +19,8 @@ patchShebangs() {
     local newInterpreterLine
 
     find "$dir" -type f -perm -0100 | while read f; do
-        if [ "$(head -1 "$f" | head -c+2)" != '#!' ]; then
-            # missing shebang => not a script
-            continue
+        if ! isScript "$f"; then
+          continue
         fi
 
         oldInterpreterLine=$(head -1 "$f" | tail -c+3)

From 286381f0727a5aee3413c24989ad5fb609653c49 Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Fri, 28 Sep 2018 11:17:33 -0500
Subject: [PATCH 2/3] patch-shebangs: simplify a bit per reviewer suggestion

---
 pkgs/build-support/setup-hooks/patch-shebangs.sh | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pkgs/build-support/setup-hooks/patch-shebangs.sh b/pkgs/build-support/setup-hooks/patch-shebangs.sh
index 0ac81102658..18eb011b0c7 100644
--- a/pkgs/build-support/setup-hooks/patch-shebangs.sh
+++ b/pkgs/build-support/setup-hooks/patch-shebangs.sh
@@ -19,9 +19,7 @@ patchShebangs() {
     local newInterpreterLine
 
     find "$dir" -type f -perm -0100 | while read f; do
-        if ! isScript "$f"; then
-          continue
-        fi
+        isScript "$f" || continue
 
         oldInterpreterLine=$(head -1 "$f" | tail -c+3)
         read -r oldPath arg0 args <<< "$oldInterpreterLine"

From f7db287960241736213c0f262ad655ce40cfc624 Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Fri, 28 Sep 2018 11:21:51 -0500
Subject: [PATCH 3/3] patch-shebangs.sh: use more robust 'for each file' loop,
 check for dir

The latter is to avoid warnings printed by find if it doesn't exist.
---
 pkgs/build-support/setup-hooks/patch-shebangs.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/pkgs/build-support/setup-hooks/patch-shebangs.sh b/pkgs/build-support/setup-hooks/patch-shebangs.sh
index 18eb011b0c7..d26bf735d30 100644
--- a/pkgs/build-support/setup-hooks/patch-shebangs.sh
+++ b/pkgs/build-support/setup-hooks/patch-shebangs.sh
@@ -18,7 +18,10 @@ patchShebangs() {
     local oldInterpreterLine
     local newInterpreterLine
 
-    find "$dir" -type f -perm -0100 | while read f; do
+    [ -e "$dir" ] || return 0
+
+    local f
+    while IFS= read -r -d $'\0' f; do
         isScript "$f" || continue
 
         oldInterpreterLine=$(head -1 "$f" | tail -c+3)
@@ -58,7 +61,7 @@ patchShebangs() {
                 rm "$f.timestamp"
             fi
         fi
-    done
+    done < <(find "$dir" -type f -perm -0100 -print0)
 
     stopNest
 }