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From: Demi Marie Obenour <demiobenour@gmail.com>
To: Spectrum OS Development <devel@spectrum-os.org>
Cc: Demi Marie Obenour <demiobenour@gmail.com>, Alyssa Ross <hi@alyssa.is>
Subject: [PATCH 1/3] scripts/make-erofs.sh: Avoid unneeded calls to awk and chmod
Date: Fri, 19 Sep 2025 19:26:11 -0400	[thread overview]
Message-ID: <20250919-less-dirname-v1-1-5df7ca617b9b@gmail.com> (raw)
In-Reply-To: <20250919-less-dirname-v1-0-5df7ca617b9b@gmail.com>

These calls were made to work around permission problems, but it is much
cleaner to solve these problems by making every directory in the new
filesystem image writable so that cp can write to it.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---
Hyperfine confirms that this does improve performance, though there are
outliers.
---
 scripts/make-erofs.sh | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/scripts/make-erofs.sh b/scripts/make-erofs.sh
index b47048ad747bd7dfcc28e0f1dfd75ec090fa7e09..82d37573ad0454e79becfddd05f93585df7b671c 100755
--- a/scripts/make-erofs.sh
+++ b/scripts/make-erofs.sh
@@ -30,18 +30,18 @@ while read -r arg1; do
 	fi
 	echo
 
-	parent="$(dirname "$arg2")"
-	awk -v parent="$parent" -v root="$root" 'BEGIN {
-		n = split(parent, components, "/")
-		for (i = 1; i <= n; i++) {
-			printf "%s/", root
-			for (j = 1; j <= i; j++)
-				printf "%s/", components[j]
-			print
-		}
-	}' | xargs -rd '\n' chmod +w -- 2>/dev/null || :
-	mkdir -p -- "$root/$parent"
+	if [ "$arg2" = / ]; then
+		cp -RT -- "$arg1" "$root"
+		# Nix store paths are read-only, so fix up permissions
+		# so that subsequent copies can write to directories
+		# created by the above copy.  This means giving all
+		# directories 0755 permissions.
+		find "$root" -type d -exec chmod 0755 -- '{}' +
+		continue
+	fi
 
+	parent=$(dirname "$arg2")
+	mkdir -p -- "$root/$parent"
 	cp -RT -- "$arg1" "$root/$arg2"
 done
 

-- 
2.51.0


  reply	other threads:[~2025-09-19 23:28 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-19 23:26 [PATCH 0/3] Optimize scripts/make-erofs.sh Demi Marie Obenour
2025-09-19 23:26 ` Demi Marie Obenour [this message]
2025-09-21 11:31   ` [PATCH 1/3] scripts/make-erofs.sh: Avoid unneeded calls to awk and chmod Alyssa Ross
2025-09-21 15:56     ` Demi Marie Obenour
2025-09-21 16:15       ` Alyssa Ross
2025-09-21 17:12         ` Demi Marie Obenour
2025-09-21 18:06         ` Demi Marie Obenour
2025-09-19 23:26 ` [PATCH 2/3] scripts/make-erofs.sh: Avoid calls to dirname Demi Marie Obenour
2025-09-21 11:40   ` Alyssa Ross
2025-09-23 18:54   ` Alyssa Ross
2025-09-19 23:26 ` [PATCH 3/3] scripts/make-erofs.sh: Avoid unneeded calls to mkdir Demi Marie Obenour
2025-09-21 18:36   ` Alyssa Ross
2025-09-21 18:37     ` Demi Marie Obenour
2025-09-23 14:35       ` Alyssa Ross
2025-09-23 18:06         ` Demi Marie Obenour
2025-09-23 18:56           ` Alyssa Ross
2025-09-23 21:41             ` Demi Marie Obenour

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