[ostree] pull: Support specifying exact commit to pull via branch commit

[Colin Walters <walters src gnome org>]

commit 42c60effbe5037d674ce4b84979ccaf91edfad48
Author: Colin Walters <walters verbum org>
Date:   Thu Feb 11 13:28:03 2016 -0500

    pull: Support specifying exact commit to pull via branch commit
    
    I don't know why we didn't do this a long time ago.  This extends the
    pull API to allow grabbing a specific commit, and will set the branch
    to it.  There's some support for this in the deploy engine, but there
    are a lot of reasons to support it for raw pulls (such as subset
    mirroring cases).
    
    In fact I'm thinking we should also have the override-version logic
    here too.
    
    NOTE: One thing I debated here is inventing a new syntax on the
    command line.  Git doesn't seem to have this functionality (probably
    because it'd be rarely used). The '@' character at least doesn't
    conflict with anything.
    
    Anyways, I wanted this for some other test cases.  Without this,
    writing tests that go between different commits is more awkward as one
    must generate the content in one repo, then pull downstream, then
    generate more content, then pull again.  But now I can just keep track
    of commit IDs and do exactly what I want without synchronizing the
    tests.

 man/ostree-pull.xml              |   27 ++++++++++++++++-
 src/libostree/ostree-repo-pull.c |   57 +++++++++++++++++++++++++------------
 src/libostree/ostree-repo.c      |    1 +
 src/ostree/ot-builtin-pull.c     |   38 +++++++++++++++++++++++--
 tests/pull-test.sh               |   15 ++++++++++
 5 files changed, 114 insertions(+), 24 deletions(-)
---
diff --git a/man/ostree-pull.xml b/man/ostree-pull.xml
index d915bcd..c419307 100644
--- a/man/ostree-pull.xml
+++ b/man/ostree-pull.xml
@@ -111,14 +111,37 @@ Boston, MA 02111-1307, USA.
         <title>Description</title>
 
         <para>
-            Downloads all content corresponding to the provided branch or commit from the given remote.
+         This command can retrieve just a specific commit, or go all
+         the way to performing a full mirror of the remote
+         repository.  If no <literal>BRANCH</literal> is specified,
+         all branches are retrieved.
         </para>
+
+       <para>
+         A special syntax in the <literal>@</literal> character allows
+         specifying a specific commit to retrieve from a branch.  This
+       </para>
+
     </refsect1>
 
     <refsect1>
         <title>Example</title>
 
-        <para><command>$ ostree pull remote_name</command></para>
+        <para><command>$ ostree --repo=repo pull --depth=-1 --mirror remote_name</command></para>
+
+       <para>Perform a complete mirror of the remote.  (This is
+       likely most useful if your repository is also
+       <literal>archive-z2</literal> mode)</para>
+
+        <para><command>$ ostree --repo=repo pull remote_name exampleos/x86_64/standard</command></para>
+
+       <para>Fetch the most recent commit to <literal>exampleos/x86_64/standard</literal>.</para>
+
+        <para><command>$ ostree --repo=repo pull remote_name exampleos/x86_64/standard 
98ea6e4f216f2fb4b69fff9b3a44842c38686ca685f3f55dc48c5d3fb1107be4</command></para>
+
+       <para>Download the specific commit starting with
+       <literal>98ea6e</literal> as if it was the latest commit for
+       <literal>exampleos/x86_64/standard</literal>.</para>
     </refsect1>
 
 </refentry>
diff --git a/src/libostree/ostree-repo-pull.c b/src/libostree/ostree-repo-pull.c
index 750c68f..88b468b 100644
--- a/src/libostree/ostree-repo-pull.c
+++ b/src/libostree/ostree-repo-pull.c
@@ -1762,6 +1762,7 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
   OstreeRepoPullFlags flags = 0;
   const char *dir_to_pull = NULL;
   char **refs_to_fetch = NULL;
+  char **override_commit_ids = NULL;
   GSource *update_timeout = NULL;
   gboolean disable_static_deltas = FALSE;
 
@@ -1776,9 +1777,12 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
       (void) g_variant_lookup (options, "override-remote-name", "s", &pull_data->remote_name);
       (void) g_variant_lookup (options, "depth", "i", &pull_data->maxdepth);
       (void) g_variant_lookup (options, "disable-static-deltas", "b", &disable_static_deltas);
+      (void) g_variant_lookup (options, "override-commit-ids", "^a&s", &override_commit_ids);
     }
 
   g_return_val_if_fail (pull_data->maxdepth >= -1, FALSE);
+  if (refs_to_fetch && override_commit_ids)
+    g_return_val_if_fail (g_strv_length (refs_to_fetch) == g_strv_length (override_commit_ids), FALSE);
 
   if (dir_to_pull)
     g_return_val_if_fail (dir_to_pull[0] == '/', FALSE);
@@ -2069,8 +2073,10 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
     } 
   else if (refs_to_fetch != NULL)
     {
-      char **strviter;
-      for (strviter = refs_to_fetch; *strviter; strviter++)
+      char **strviter = refs_to_fetch;
+      char **commitid_strviter = override_commit_ids ? override_commit_ids : NULL;
+
+      while (*strviter)
         {
           const char *branch = *strviter;
 
@@ -2081,8 +2087,13 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
             }
           else
             {
-              g_hash_table_insert (requested_refs_to_fetch, g_strdup (branch), NULL);
+              char *commitid = commitid_strviter ? g_strdup (*commitid_strviter) : NULL;
+              g_hash_table_insert (requested_refs_to_fetch, g_strdup (branch), commitid);
             }
+          
+          strviter++;
+          if (commitid_strviter)
+            commitid_strviter++;
         }
     }
   else
@@ -2109,28 +2120,36 @@ ostree_repo_pull_with_options (OstreeRepo             *self,
   while (g_hash_table_iter_next (&hash_iter, &key, &value))
     {
       const char *branch = key;
+      const char *override_commitid = value;
       char *contents = NULL;
 
-      if (pull_data->summary)
+      /* Support specifying "" for an override commitid */
+      if (override_commitid && *override_commitid)
         {
-          gsize commit_size = 0;
-          guint64 *malloced_size;
-
-          if (!lookup_commit_checksum_from_summary (pull_data, branch, &contents, &commit_size, error))
-            goto out;
-
-          malloced_size = g_new0 (guint64, 1);
-          *malloced_size = commit_size;
-          g_hash_table_insert (pull_data->expected_commit_sizes, g_strdup (contents), malloced_size);
+          g_hash_table_replace (requested_refs_to_fetch, g_strdup (branch), g_strdup (override_commitid));
         }
-      else
+      else    
         {
-          if (!fetch_ref_contents (pull_data, branch, &contents, cancellable, error))
-            goto out;
+          if (pull_data->summary)
+            {
+              gsize commit_size = 0;
+              guint64 *malloced_size;
+
+              if (!lookup_commit_checksum_from_summary (pull_data, branch, &contents, &commit_size, error))
+                goto out;
+
+              malloced_size = g_new0 (guint64, 1);
+              *malloced_size = commit_size;
+              g_hash_table_insert (pull_data->expected_commit_sizes, g_strdup (contents), malloced_size);
+            }
+          else
+            {
+              if (!fetch_ref_contents (pull_data, branch, &contents, cancellable, error))
+                goto out;
+            }
+          /* Transfer ownership of contents */
+          g_hash_table_replace (requested_refs_to_fetch, g_strdup (branch), contents);
         }
-      
-      /* Transfer ownership of contents */
-      g_hash_table_replace (requested_refs_to_fetch, g_strdup (branch), contents);
     }
 
   /* Create the state directory here - it's new with the commitpartial code,
diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 2136208..1e9673d 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -3784,6 +3784,7 @@ ostree_repo_pull_one_dir (OstreeRepo               *self,
  *   * flags (i): An instance of #OstreeRepoPullFlags
  *   * refs: (as): Array of string refs
  *   * depth: (i): How far in the history to traverse; default is 0, -1 means infinite
+ *   * override-commit-ids: (as): Array of specific commit IDs to fetch for refs
  */
 gboolean
 ostree_repo_pull_with_options (OstreeRepo             *self,
diff --git a/src/ostree/ot-builtin-pull.c b/src/ostree/ot-builtin-pull.c
index 6aae820..63dbc76 100644
--- a/src/ostree/ot-builtin-pull.c
+++ b/src/ostree/ot-builtin-pull.c
@@ -34,7 +34,7 @@ static gboolean opt_disable_static_deltas;
 static char* opt_subpath;
 static int opt_depth = 0;
  
- static GOptionEntry options[] = {
+static GOptionEntry options[] = {
    { "commit-metadata-only", 0, 0, G_OPTION_ARG_NONE, &opt_commit_only, "Fetch only the commit metadata", 
NULL },
    { "disable-fsync", 0, 0, G_OPTION_ARG_NONE, &opt_disable_fsync, "Do not invoke fsync()", NULL },
    { "disable-static-deltas", 0, 0, G_OPTION_ARG_NONE, &opt_disable_static_deltas, "Do not use static 
deltas", NULL },
@@ -70,6 +70,7 @@ ostree_builtin_pull (int argc, char **argv, GCancellable *cancellable, GError **
   OstreeRepoPullFlags pullflags = 0;
   GSConsole *console = NULL;
   g_autoptr(GPtrArray) refs_to_fetch = NULL;
+  g_autoptr(GPtrArray) override_commit_ids = NULL;
   glnx_unref_object OstreeAsyncProgress *progress = NULL;
   gulong signal_handler_id = 0;
 
@@ -102,9 +103,36 @@ ostree_builtin_pull (int argc, char **argv, GCancellable *cancellable, GError **
       if (argc > 2)
         {
           int i;
-          refs_to_fetch = g_ptr_array_new ();
+          refs_to_fetch = g_ptr_array_new_with_free_func (g_free);
+
           for (i = 2; i < argc; i++)
-            g_ptr_array_add (refs_to_fetch, argv[i]);
+            {
+              const char *at = strrchr (argv[i], '@');
+
+              if (at)
+                {
+                  guint j;
+                  const char *override_commit_id = at + 1;
+
+                  if (!ostree_validate_checksum_string (override_commit_id, error))
+                    goto out;
+
+                  if (!override_commit_ids)
+                    override_commit_ids = g_ptr_array_new_with_free_func (g_free);
+
+                  /* Backfill */
+                  for (j = 2; j < i; i++)
+                    g_ptr_array_add (override_commit_ids, g_strdup (""));
+
+                  g_ptr_array_add (override_commit_ids, g_strdup (override_commit_id));
+                  g_ptr_array_add (refs_to_fetch, g_strndup (argv[i], at - argv[i]));
+                }
+              else
+                {
+                  g_ptr_array_add (refs_to_fetch, g_strdup (argv[i]));
+                }
+            }
+
           g_ptr_array_add (refs_to_fetch, NULL);
         }
     }
@@ -147,6 +175,10 @@ ostree_builtin_pull (int argc, char **argv, GCancellable *cancellable, GError **
     g_variant_builder_add (&builder, "{s v}", "disable-static-deltas",
                            g_variant_new_variant (g_variant_new_boolean (opt_disable_static_deltas)));
 
+    if (override_commit_ids)
+      g_variant_builder_add (&builder, "{s v}", "override-commit-ids",
+                             g_variant_new_variant (g_variant_new_strv ((const 
char*const*)override_commit_ids->pdata, override_commit_ids->len)));
+
     if (!ostree_repo_pull_with_options (repo, remote, g_variant_builder_end (&builder),
                                         progress, cancellable, error))
       goto out;
diff --git a/tests/pull-test.sh b/tests/pull-test.sh
index 6f0b651..2233b90 100755
--- a/tests/pull-test.sh
+++ b/tests/pull-test.sh
@@ -73,6 +73,21 @@ assert_file_has_content main-meta "HANCOCK"
 echo "ok pull detached metadata"
 
 cd ${test_tmpdir}
+mkdir parentpullrepo
+${CMD_PREFIX} ostree --repo=parentpullrepo init --mode=archive-z2
+${CMD_PREFIX} ostree --repo=parentpullrepo remote add --set=gpg-verify=false origin 
file://$(pwd)/ostree-srv/gnomerepo
+parent_rev=$(ostree --repo=ostree-srv/gnomerepo rev-parse main^)
+rev=$(ostree --repo=ostree-srv/gnomerepo rev-parse main)
+${CMD_PREFIX} ostree --repo=parentpullrepo pull origin main ${parent_rev}
+${CMD_PREFIX} ostree --repo=parentpullrepo rev-parse origin:main > main.txt
+assert_file_has_content main.txt ${parent_rev}
+${CMD_PREFIX} ostree --repo=parentpullrepo fsck
+${CMD_PREFIX} ostree --repo=parentpullrepo pull origin main
+${CMD_PREFIX} ostree --repo=parentpullrepo rev-parse origin:main > main.txt
+assert_file_has_content main.txt ${rev}
+echo "ok pull specific commit"
+
+cd ${test_tmpdir}
 repo_init
 ${CMD_PREFIX} ostree --repo=repo pull origin main
 ${CMD_PREFIX} ostree --repo=repo fsck