From 7fb468b76d0a503897f492a98e9b9f7f238c6a50 Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Fri, 30 Nov 2018 17:10:20 +1300
Subject: Add Makefile and manual page

---
 watch-git-tags.sh | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 watch-git-tags.sh

(limited to 'watch-git-tags.sh')

diff --git a/watch-git-tags.sh b/watch-git-tags.sh
new file mode 100644
index 0000000..b9fdce8
--- /dev/null
+++ b/watch-git-tags.sh
@@ -0,0 +1,84 @@
+#!/bin/sh
+
+# List sorted local tags
+tags_local() {
+    for repo ; do
+        git -C "$repo" tag --list | LC_COLLATE=C sort
+    done
+}
+
+# List sorted remote tags
+tags_remote() {
+    for repo ; do
+        git -C "$repo" ls-remote --quiet --refs --tags ||
+            printf >&2 'Failed to retrieve tags for repository %s\n' "$PWD"
+    done |
+    while read -r _ tag ; do
+        tag=${tag#refs/tags/}
+        printf '%s\n' "$tag"
+    done
+}
+
+# Create a temporary directory with name in $td, and handle POSIX-ish traps to
+# remove it when the script exits; requires mktemp(1) (not POSIX)
+td=$(mktemp -d) || exit
+cleanup() {
+    [ -n "$td" ] || return
+    rm -fr -- "$td"
+}
+for sig in EXIT HUP INT TERM ; do
+    # shellcheck disable=SC2064
+    trap "cleanup $sig" "$sig"
+done
+
+# Use current directory if no other arguments
+[ "$#" -gt 0 ] || set -- .
+
+# Iterate through each repo in a subshell in parallel
+for repo ; do (
+
+    # Make a temporary directory with a hash in its name for uniqueness
+    name=$(printf '%s' "$repo" | sed 's:/:_:g')
+    cksum=$(printf '%s' "$repo" | cksum | sed 's:[^0-9].*::')
+    sd=$td/$name.$cksum
+    mkdir -- "$sd" "$sd"/tags || exit
+
+    # Step in and write repo path to file
+    cd -- "$sd" || exit
+    printf '%s\n' "$repo" > path || exit
+
+    # Write local and remote tags to files
+    tags_local "$repo" > tags/local || exit
+    tags_remote "$repo" > tags/remote || exit
+
+    # Write new tags to file
+    LC_COLLATE=C comm -13 -- tags/local tags/remote > tags/new
+
+    # Attempt to quietly fetch new tags so that we don't notify about the same
+    # ones next time
+    [ -s tags/new ] || exit
+    git -C "$repo" fetch --quiet --tags
+
+) & done
+
+# Wait for all of those to finish
+wait
+
+# Iterate through the temp dirs in order
+for dir in "$td"/* ; do (
+    cd -- "$dir" || exit
+
+    # Look for non-zero "new" files (at least one new tag)
+    [ -s tags/new ] || exit
+
+    # Print repository path and new tags
+    cat path
+    while read -r tag ; do
+        printf '* %s\n' "$tag"
+    done < tags/new
+
+) ; done
+
+# Haven't yet decided on exit value semantics; for the moment, if it completes,
+# exit success
+exit 0
-- 
cgit v1.2.3