extras: make mksboarchive resolve the package from CWD

The previous version derived the repo root from the script's own location via
git, which broke once the script was installed outside the repo (e.g. ~/bin):
it ran git in ~/bin and failed with 'not a git repository'. Resolve the
package as <pkg>/ below the current directory instead and run from the repo
root. The installed copy now works identically. README updated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2 files changed, 19 insertions, 16 deletions

diff --git a/.extras/mksboarchive b/.extras/mksboarchive
index a53fbf4..fc54709 100755
--- a/.extras/mksboarchive
+++ b/.extras/mksboarchive
@@ -8,9 +8,10 @@ usage() {
 usage: ${0##*/} <package-name>
 
 Build the SBo submission tarball <package-name>.tar.gz, the same archive the
-post-commit hook produces, on demand by name. The package must exist in this
-repo (<package-name>/<package-name>.SlackBuild). Any sbodl source symlinks in
-the package directory are removed first so they never leak into the tarball.
+post-commit hook produces, on demand by name. Run from the repo root: the
+package is the <package-name>/ directory below the current directory, with a
+matching <package-name>.SlackBuild. Any sbodl source symlinks in the package
+directory are removed first so they never leak into the tarball.
 
 Output goes to the current directory by default; set OUTPUT to override:
   OUTPUT=/tmp ${0##*/} feroxbuster   # writes /tmp/feroxbuster.tar.gz
@@ -23,22 +24,22 @@ esac
 [ $# -eq 1 ] || { usage >&2; exit 2; }
 
 pkg=$1
-REPO_ROOT=$(git -C "$(dirname "$0")" rev-parse --show-toplevel)
 
-# Where the tarball lands. Defaults to the current directory; override with
-# the OUTPUT env var (e.g. OUTPUT=/tmp mksboarchive feroxbuster).
+# Run this from the repo root. The package is the <pkg>/ directory below the
+# current directory; the tarball is written to the current directory by
+# default, override with the OUTPUT env var.
 OUTPUT=${OUTPUT:-$PWD}
 
-# Must be a real package dir one level deep with a matching .SlackBuild.
-if [ ! -f "$REPO_ROOT/$pkg/$pkg.SlackBuild" ]; then
-    echo "error: '$pkg' is not a package in this repo." >&2
+# Must be a real package dir below CWD with a matching .SlackBuild.
+if [ ! -f "$pkg/$pkg.SlackBuild" ]; then
+    echo "error: no '$pkg/$pkg.SlackBuild' here. Run from the repo root." >&2
     exit 1
 fi
 
 # Drop any sbodl source symlinks before archiving so they never end up in an
 # SBo submission tarball (the pre-commit hook does the same for staged files).
-find "$REPO_ROOT/$pkg" -type l -delete
+find "$pkg" -type l -delete
 
 mkdir -p "$OUTPUT"
-tar -czf "$OUTPUT/$pkg.tar.gz" -C "$REPO_ROOT" "$pkg"
+tar -czf "$OUTPUT/$pkg.tar.gz" "$pkg"
 echo "Archive created: $OUTPUT/$pkg.tar.gz"
diff --git a/README.md b/README.md
index 207afc6..f2142c2 100644
--- a/README.md
+++ b/README.md
@@ -73,11 +73,13 @@ rather than at commit time:
 OUTPUT=/tmp .extras/mksboarchive hydra   # writes /tmp/hydra.tar.gz
 ```
 
-It validates that `<package>/<package>.SlackBuild` exists, removes any
-`sbodl` source symlinks from the package directory first (so they never leak
-into the tarball), then archives the directory. The output directory defaults
-to the current working directory and can be overridden with the `OUTPUT`
-environment variable. Run it from anywhere; it locates the repo root via git.
+Run it from the repo root: it looks for a `<package>/<package>.SlackBuild`
+below the current directory, removes any `sbodl` source symlinks from the
+package directory first (so they never leak into the tarball), then archives
+the directory. The output directory defaults to the current working directory
+and can be overridden with the `OUTPUT` environment variable. This means it
+works the same whether you run `.extras/mksboarchive` or an installed copy
+(e.g. in `~/bin`), as long as you are in the repo root.
 
 ## Vendored Crates (Rust packages)