git-r3.eclass: Support checking out repo by date, #510704

diff --git a/eclass/git-r3.eclass b/eclass/git-r3.eclass
index b7a93338951c64cee9c55e1f3e6f132de372d6fe..0ac9d908729e1ea1c28a1655ba7489409887ac5a 100644 (file)
--- a/eclass/git-r3.eclass
+++ b/eclass/git-r3.eclass
@@ -159,6 +159,21 @@ fi
 #
 # It can be overriden via env using ${PN}_LIVE_COMMIT variable.
 
+# @ECLASS-VARIABLE: EGIT_COMMIT_DATE
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# Attempt to check out the repository state for the specified timestamp.
+# The date should be in format understood by 'git rev-list'.
+#
+# The eclass will select the last commit with commit date preceding
+# the specified date. When merge commits are found, only first parents
+# will be considered in order to avoid switching into external branches
+# (assuming that merges are done correctly). In other words, each merge
+# will be considered alike a single commit with date corresponding
+# to the merge commit date.
+#
+# It can be overriden via env using ${PN}_LIVE_COMMIT_DATE variable.
+
 # @ECLASS-VARIABLE: EGIT_CHECKOUT_DIR
 # @DESCRIPTION:
 # The directory to check the git sources out to.
@@ -254,6 +269,15 @@ _git-r3_env_setup() {
        [[ ${!livevar} ]] \
                && ewarn "Using ${livevar}, no support will be provided"
 
+       livevar=${esc_pn}_LIVE_COMMIT_DATE
+       EGIT_COMMIT_DATE=${!livevar-${EGIT_COMMIT_DATE}}
+       [[ ${!livevar} ]] \
+               && ewarn "Using ${livevar}, no support will be provided"
+
+       if [[ ${EGIT_COMMIT} && ${EGIT_COMMIT_DATE} ]]; then
+               die "EGIT_COMMIT and EGIT_COMMIT_DATE can not be specified simultaneously"
+       fi
+
        # Migration helpers. Remove them when git-2 is removed.
 
        if [[ ${EGIT_SOURCEDIR} ]]; then
@@ -495,7 +519,7 @@ _git-r3_is_local_repo() {
 }
 
 # @FUNCTION: git-r3_fetch
-# @USAGE: [<repo-uri> [<remote-ref> [<local-id>]]]
+# @USAGE: [<repo-uri> [<remote-ref> [<local-id> [<commit-date>]]]]
 # @DESCRIPTION:
 # Fetch new commits to the local clone of repository.
 #
@@ -518,6 +542,9 @@ _git-r3_is_local_repo() {
 # This default should be fine unless you are fetching multiple trees
 # from the same repository in the same ebuild.
 #
+# <commit-id> requests attempting to use repository state as of specific
+# date. For more details, see EGIT_COMMIT_DATE.
+#
 # The fetch operation will affect the EGIT_STORE only. It will not touch
 # the working copy, nor export any environment variables.
 # If the repository contains submodules, they will be fetched
@@ -538,6 +565,7 @@ git-r3_fetch() {
        local remote_ref=${2:-${EGIT_COMMIT:-${branch:-HEAD}}}
        local local_id=${3:-${CATEGORY}/${PN}/${SLOT%/*}}
        local local_ref=refs/git-r3/${local_id}/__main__
+       local commit_date=${4:-${EGIT_COMMIT_DATE}}
 
        [[ ${repos[@]} ]] || die "No URI provided and EGIT_REPO_URI unset"
 
@@ -621,6 +649,11 @@ git-r3_fetch() {
                                        fi
                                fi
 
+                               # checkout by date does not make sense in shallow mode
+                               if [[ ${commit_date} && ${clone_type} == shallow ]]; then
+                                       clone_type=single
+                               fi
+
                                if [[ ${fetch_l} == HEAD ]]; then
                                        fetch_r=refs/git-r3/HEAD
                                else
@@ -667,17 +700,31 @@ git-r3_fetch() {
                fi
 
                # now let's see what the user wants from us
-               local full_remote_ref=$(
-                       git rev-parse --verify --symbolic-full-name "${remote_ref}"
-               )
-
-               if [[ ${full_remote_ref} ]]; then
-                       # when we are given a ref, create a symbolic ref
-                       # so that we preserve the actual argument
-                       set -- git symbolic-ref "${local_ref}" "${full_remote_ref}"
+               if [[ ${commit_date} ]]; then
+                       local dated_commit_id=$(
+                               git rev-list --first-parent --before="${commit_date}" \
+                                       -n 1 "${remote_ref}"
+                       )
+                       if [[ ${?} -ne 0 ]]; then
+                               die "Listing ${remote_ref} failed (wrong ref?)."
+                       elif [[ ! ${dated_commit_id} ]]; then
+                               die "Unable to find commit for date ${commit_date}."
+                       else
+                               set -- git update-ref --no-deref "${local_ref}" "${dated_commit_id}"
+                       fi
                else
-                       # otherwise, we were likely given a commit id
-                       set -- git update-ref --no-deref "${local_ref}" "${remote_ref}"
+                       local full_remote_ref=$(
+                               git rev-parse --verify --symbolic-full-name "${remote_ref}"
+                       )
+
+                       if [[ ${full_remote_ref} ]]; then
+                               # when we are given a ref, create a symbolic ref
+                               # so that we preserve the actual argument
+                               set -- git symbolic-ref "${local_ref}" "${full_remote_ref}"
+                       else
+                               # otherwise, we were likely given a commit id
+                               set -- git update-ref --no-deref "${local_ref}" "${remote_ref}"
+                       fi
                fi
 
                echo "${@}" >&2