cg-seek

   1 #!/usr/bin/env bash
   2 #
   3 # Seek the working tree to a given commit
   4 # Copyright (c) Petr Baudis, 2005
   5 #
   6 # Seeking will bring the working tree from its current 'HEAD' to a given
   7 # commit. Note that it changes just the 'HEAD' of the working tree, not
   8 # the branch it is corresponding to. It will return to the 'HEAD' of
   9 # the appropriate branch if passed no arguments.
  10 #
  11 # Therefore, for a quick excursion to the past of the 'master' branch:
  12 #
  13 #       $ cg-seek git-pasky-0.1
  14 #       $ cg-diff this master   # will do the correct thing
  15 #       $ cg-seek               # will restore what we had before
  16 #
  17 # For intuitiveness, specifying the branch name (`cg-seek master`) will do
  18 # the right thing too. If you want to migrate your working tree to _another_
  19 # branch, use `cg-clone` to create a new tree for the new branch, or
  20 # `cg-switch` to also change your current tree to use the new branch.
  21 #
  22 # Note that during the time you are seeked out, commits, merges, and some
  23 # other operations are blocked, since the next `cg-seek` or `cg-reset`
  24 # invocation will happily wipe out their products silently. You can override
  25 # this in the `cg-commit` command by passing it a '-f' parameter - this
  26 # can be useful e.g. when you seeked to a commit which cannot be compiled
  27 # and you want to commit a compilation fix, as long as you are aware that
  28 # the commit of the fix will be rendered unreachable (you will be able to
  29 # get back to it only if you remember its ID) at the moment you do next
  30 # seek or a reset. If you want to save the commit, you can save it to
  31 # a separate branch using `cg-switch -n`.
  32 #
  33 # Takes the target commit ID to seek to as an argument.
  34 #
  35 # NOTES
  36 # -----
  37 # The `cg-seek` command is meant only for temporary excursions to the commit
  38 # history. If you want to permanently switch your branch to a different commit
  39 # id (forgetting its current contents), you can use the `cg-switch` command:
  40 #
  41 #       $ cg-switch -f -r COMMIT_ID CURRENT_HEAD_NAME
  42 #
  43 # Note that this command has some serious caveats! Please read the
  44 # `cg-switch` documentation for details.
  45
  46 # Testsuite: Complete (t9300-seek)
  47
  48 USAGE="cg-seek [COMMIT_ID]"
  49 _git_requires_root=1
  50
  51 . "${COGITO_LIB}"cg-Xlib || exit 1
  52
  53 dstcommit="${ARGS[0]}"
  54
  55
  56 [ -s "$_git/blocked" ] && grep -vq '^seeked from ' "$_git/blocked" && die "action blocked: $(cat "$_git/blocked")"
  57
  58 curcommit="$(cg-object-id -c)" || exit 1
  59
  60 if [ "$dstcommit" ] && [ "$dstcommit" != "$_git_head" ]; then
  61         seek_mode=away
  62         [ -s "$_git/head-name" ] && [ "$(git-symbolic-ref HEAD)" != "refs/heads/cg-seek-point" ] &&
  63                 die "seeked away by some other tool, refusing to meddle (you can still use cg-seek without any arguments to unseek)"
  64         exists_ref "refs/heads/$dstcommit" ] &&
  65                 warn "seeking to a branch head; this is not for permanent switching, please see cg-switch"
  66 else
  67         seek_mode=back
  68         dstcommit="$(cg-object-id -c "$_git_head")" || exit 1
  69 fi
  70
  71 dstcommit="$(cg-object-id -c "$dstcommit")" || exit 1
  72 if [ "$curcommit" != "$dstcommit" ]; then
  73         tree_timewarp --no-head-update "along" "please rollback" "$curcommit" "$dstcommit" || exit 1
  74 fi
  75
  76 if [ "$seek_mode" = "away" ]; then
  77         echo "$_git_head" >"$_git/head-name"
  78         [ -s "$_git/blocked" ] || echo "seeked from $_git_head (some commands can be still forced)" >"$_git/blocked"
  79         # We hold this in a temporary branch so that some of the core
  80         # GIT tools (git checkout and git-fsck-objects) don't get confused.
  81         git-update-ref "refs/heads/cg-seek-point" "$dstcommit"
  82         git-symbolic-ref HEAD "refs/heads/cg-seek-point"
  83 else
  84         seekpt="$(get_ref "refs/heads/cg-seek-point")"
  85         git-symbolic-ref HEAD "refs/heads/$_git_head"
  86         git-update-ref -d "refs/heads/cg-seek-point" "$seekpt"
  87         rm -f "$_git/head-name"
  88         rm -f "$_git/blocked"
  89 fi
  90
  91 echo "On commit $dstcommit"