feat: add ability to downgrade aur package using git

This is fully opt-in by the `--git` option (or equivalent env var).

If enabled, we check to see if the configured cache directory represents
the git repository. This would be the case if the user is downgrading an
AUR package installed via `yay`. In such a repository, we can hunt for
commits that represent the older versions of the package and present
them as options to downgrade to. If selected, we can check out that
commit and build the package at that version (if necessary) and install
it.

The logic is isolated to a `search_git` function, for handling locating
commits that represent versions and output potential package names that
include "gitpkg" in them, and a `build_pkg` function that looks for such
package names and builds them. We have to be careful to use `su` so that
`makepkg` is not run as root. The only changes to `downgrade` outside of
these new functions is to regexs used to locate and parse package names,
but this is well covered by tests.

Author: darukutsu

dist/completion/downgrade/fish

@@ -4,6 +4,7 @@ complete -c $cmd -l pacman -xa "(complete -C(commandline -ct))" -d 'pacman comma
 complete -c $cmd -l pacman-conf -r -d 'pacman configuration file'
 complete -c $cmd -l pacman-cache -r -d 'pacman cache directory'
 complete -c $cmd -l pacman-log -r -d 'pacman log file'
+complete -c $cmd -l git -d 'uses git for choosing version, viable only for aur packages'
 complete -c $cmd -l maxdepth -x -d 'maximum depth to search for cached packages'
 complete -c $cmd -l ala-url -x -d 'location of ALA server'
 complete -c $cmd -l ala-only -d 'only use ALA server'

dist/completion/downgrade/zsh

@@ -20,6 +20,7 @@ _downgrade () {
     '--pacman-conf[pacman configuration file]:pacman config file:_files' \
     '*--pacman-cache[pacman cache directory]:pacman cache directory:_path_files -/' \
     '--pacman-log[pacman log file]:pacman log file:_files' \
+    '--git[uses git for choosing version, viable only for aur packages]' \
     '--maxdepth[maximum depth to search for cached packages]:maximum search depth' \
     '--ala-url[location of ALA server]:ala url' \
     '--ala-only[only use ALA server]' \

doc/downgrade.8.ronn

@@ -72,6 +72,15 @@ on the ALA.
     Pacman log file, default value is extracted from pacman configuration file, or
     otherwise defaults to _/var/log/pacman.log_.
 
+  * `--git`:
+    If the pacman cache contains the source repository for the package (e.g. if
+    you use yay and are downgrading an AUR package), present any version-like
+    tags as available for downgrading (together with cached packages if
+    present). If selected, build and install the package from sources checked
+    out at that tag.
+
+    See [EXAMPLES].
+
   * `--maxdepth`=<INTEGER>:
     Maximum depth to search for cached packages, defaults to _1_.
 
@@ -168,6 +177,11 @@ Non-interactively downgrade `foo` to `1.0.0-1`
 
     # downgrade --latest --prefer-cache --ignore never 'foo=1.0.0-1'
 
+Present cached `downgrade` pkgbuilds together with tags with version greater
+than 9
+
+    # downgrade --git --pacman-cache ~/.cache/yay --maxdepth 2 'downgrade>9.0.0'
+
 ## AUTHORS
 
 * Patrick Brisbin \<pbrisbin@gmail.com>

src/downgrade

@@ -19,6 +19,7 @@ $(gettext "Options"):
                   $(gettext "pacman log file,")
                   $(gettext "default value taken from pacman configuration file,")
                   $(gettext "or otherwise defaults to") "/var/log/pacman.log"
+  --git           $(gettext "uses git for choosing version, viable only for aur packages")
   --maxdepth      <$(gettext "integer")>
                   $(gettext "maximum depth to search for cached packages, defaults to") 1
   --ala-url       <url>
@@ -167,8 +168,10 @@ matches_name_version_filter() {
     return 0
   fi
 
-  version_regex="[^-]+-[0-9.]+"
-  pkg_version=$(sed -r "s/.*$name-($version_regex)-(any|$DOWNGRADE_ARCH)\\.pkg\\.tar\\.(gz|xz|zst)/\1/g" <<<"$pkg")
+  # version: 2025.11.12.r15.g0eed3fe
+  version_regex="[a-zA-Z0-9.]+"
+  hash_or_minor="([0-9]+|[a-z0-9]{6,})"
+  pkg_version=$(sed -r "s/.*$name-($version_regex)(-$hash_or_minor)?-(any|$DOWNGRADE_ARCH)\\.(git)?pkg\\.tar\\.(gz|xz|zst)/\1\2/g" <<<"$pkg")
   cmp=$(vercmp "$pkg_version" "$search_version")
 
   case "$operator" in
@@ -196,6 +199,34 @@ matches_name_version_filter() {
   esac
 }
 
+search_git() {
+  local name=$1 pairs path
+
+  # Delay this defaulting so #read_pacman_conf behavior is tested
+  if ((!${#PACMAN_CACHE[@]})); then
+    mapfile -t PACMAN_CACHE < <(read_pacman_conf CacheDir)
+  fi
+
+  for cache in "${PACMAN_CACHE[@]}"; do
+    path="$cache/$name" # directory name
+    if ! [[ -d "$path/.git" ]]; then
+      {
+        gettext "\`$path\" not a git directory, skipping..."
+        echo
+      } >&2
+      continue
+    fi
+
+    # TODO: in future could be enhanced by counting every commit
+    # that DOES NOT change version as minor like 0.0.1-2 instead of any
+    # pair = abcd12 1.0
+    pairs=$(git -C "$path" log -p --oneline --format="GIT: %h" PKGBUILD | grep -e 'GIT:.*' -e '+pkgver' | grep -Pzo 'GIT: .*\n\+pkgver=.*\n' | sed 's/GIT: \|+pkgver=//' | tr -d '\0')
+
+    # shellcheck disable=SC2086
+    echo "$path/$name" $pairs | awk '{for(i=2;i<NF;i+=2) printf "%s-%s-%s-any.gitpkg.tar.gz\n", $1, $(i+1), $i}' | sort -V
+  done
+}
+
 search_ala() {
   local name=$1 uriname pkgfile_re index
 
@@ -217,7 +248,10 @@ search_ala() {
 search_cache() {
   local name=$1 pkgfile_re index
 
-  pkgfile_re="$name-[^-]+-[0-9.]+-(any|$DOWNGRADE_ARCH)\\.pkg\\.tar\\.(gz|xz|zst)"
+  # version: 2025.11.12.r15.g0eed3fe
+  version_regex="[a-zA-Z0-9.]+"
+  hash_or_minor="([0-9]+|[a-z0-9]{6,})"
+  pkgfile_re="$name-($version_regex)(-$hash_or_minor)?-(any|$DOWNGRADE_ARCH)\\.pkg\\.tar\\.(gz|xz|zst)"
 
   # Delay this defaulting so #read_pacman_conf behavior is tested
   if ((!${#PACMAN_CACHE[@]})); then
@@ -258,7 +292,7 @@ output_package() {
   fi
 
   # Remote or local file
-  if [[ $path =~ ^/ ]]; then
+  if [[ $path =~ ^/ && ! ($path =~ gitpkg) ]]; then
     location="$(dirname "$path")"
     timestamp=$(stat -c '%y' "$path" | cut -d' ' -f1)
   else
@@ -293,7 +327,7 @@ extract_version_parts() {
     s|^.\{'${#pkgname}'\}-\?||;
 
     # Strip package extension
-    s|\.pkg\(\.tar\)\?\(\.[a-z0-9A-Z]\+\)\?$||;
+    s|\.\(git\)\?pkg\(\.tar\)\?\(\.[a-z0-9A-Z]\+\)\?$||;
 
     # (epoch:)?version(-release)?(-arch)? -> epoch,version,release,arch
     s|\(\([^:]*\):\)\?\([^-]*\)\(-\([^-]*\)\)\?\(-\(.*\)\)\?|\2,\3,\5,\7|;
@@ -320,6 +354,11 @@ process_term() {
 
   candidates=($(printf '%s\n' "${candidates[@]}" | sort_packages))
 
+  # this is already sorted
+  if ((DOWNGRADE_FROM_GIT)); then
+    candidates=($(search_git "$name" | filter_packages "$name" "$operator" "$version") "${candidates[@]}")
+  fi
+
   if (("${#candidates[@]}" == 0)); then
     {
       gettext "No results found"
@@ -440,6 +479,9 @@ parse_options() {
           exit 1
         fi
         ;;
+      --git)
+        DOWNGRADE_FROM_GIT=1
+        ;;
       --maxdepth)
         if [[ -n "$2" ]]; then
           shift
@@ -523,6 +565,34 @@ parse_options() {
   fi
 }
 
+build_pkg() {
+  local item="$1" path commit_hash build_failed versionreg hashreg gitpkgreg
+  if [[ "$item" =~ .*gitpkg.tar.gz ]]; then
+    # version: 2025.11.12.r15.g0eed3fe
+    versionreg="([a-zA-Z0-9]+\.?)*"
+    hashreg='[a-z0-9]{6,}'
+    #hash_or_minor="-([0-9]+|[a-z0-9]{6,})" # leaving this as a note, only hash should appear tho
+    gitpkgreg="(.*)-$versionreg-($hashreg)-(any|$DOWNGRADE_ARCH).gitpkg.tar.gz"
+    path=$(dirname "$item")
+    commit_hash=$(sed -r "s/$gitpkgreg/\3/" <<<"$item")
+
+    pushd "$path" >/dev/null
+    su -P "$(stat -c"%U" PKGBUILD)" -c "git checkout $commit_hash &>/dev/null && makepkg -fs | tee makepkg.log"
+    build_failed=$?
+    # NOTE: when force-canceling, users might need to manually do checkout master
+    # otherwise they won't be able to update that pkg using yay or whatever I guess...
+    su "$(stat -c"%U" PKGBUILD)" -c "git switch - &>/dev/null"
+    if ((build_failed)); then
+      exit 1
+    fi
+
+    item="$(find "$path" -maxdepth 1 -type f -name "$(sed -nr '/.*Finished making: ([^ ]+) ([^ ]+) .*/{s//\1-\2/;p}' makepkg.log)*" -print -quit)"
+    rm makepkg.log
+    popd >/dev/null
+  fi
+  printf "%s\0" "$item" >>new_to_install.downgrade
+}
+
 cli() {
   local conf_args=()
 
@@ -536,6 +606,14 @@ cli() {
 
   # Proceed with rest of workflow
   main "${terms[@]}"
+  if ((DOWNGRADE_FROM_GIT)); then
+    for item in "${to_install[@]}"; do
+      build_pkg "$item"
+    done
+    mapfile -d '' to_install <new_to_install.downgrade
+    rm new_to_install.downgrade
+  fi
+
   pacman -U "${pacman_args[@]}" "${to_install[@]}"
   prompt_to_ignore "${to_ignore[@]}"
 }
@@ -545,6 +623,7 @@ PACMAN="pacman"
 PACMAN_CONF="/etc/pacman.conf"
 DOWNGRADE_ARCH="$(pacman-conf Architecture | head -n 1)"
 DOWNGRADE_ALA_URL="https://archive.archlinux.org"
+DOWNGRADE_FROM_GIT=0
 DOWNGRADE_FROM_ALA=1
 DOWNGRADE_FROM_CACHE=1
 DOWNGRADE_MAXDEPTH=1

test/search_git.t

@@ -0,0 +1,16 @@
+  $ source "$TESTDIR/helper.sh"
+  > cache=$(mktemp -d)
+  > git clone -q "https://aur.archlinux.org/downgrade.git" "$cache/downgrade"
+  > write_pacman_conf "[options]" "CacheDir = $cache"
+  > export DOWNGRADE_FROM_GIT=1
+
+List packages based on git tags
+
+  $ search_git 'downgrade' | head -n 2
+  /tmp/*/downgrade-5.1.3-0bdb507-any.gitpkg.tar.gz (glob)
+  /tmp/*/downgrade-5.1.4-dee7bd9-any.gitpkg.tar.gz (glob)
+
+Outputs appropriately for filter_packages
+
+  $ search_git 'downgrade' | filter_packages 'downgrade' '=~' '^7' | head -n 1
+  /tmp/*/downgrade-7.0.0-513f504-any.gitpkg.tar.gz (glob)