bash prompt: combine 'git rev-parse' for detached head
When describing a detached HEAD according to the $GIT_PS1_DESCRIBE
environment variable fails, __git_ps1() now runs the '$(git rev-parse
--short HEAD)' command substitution to get the abbreviated detached
HEAD commit object name. This imposes the overhead of fork()ing a
subshell and fork()+exec()ing a git process.
Avoid this overhead by combining this command substitution with the
"main" 'git rev-parse' execution for getting the path to the .git
directory & co. This means that we'll look for the abbreviated commit
object name even when it's not necessary, because we're on a branch or
the detached HEAD can be described. It doesn't matter, however,
because once 'git rev-parse' is up and running to fulfill all those
other queries, the additional overhead of looking for the abbreviated
commit object name is not measurable because it's lost in the noise.
There is a caveat, however, when we are on an unborn branch, because
in that case HEAD doesn't point to a valid commit, hence the query for
the abbreviated commit object name fails. Therefore, '--short HEAD'
must be the last options to 'git rev-parse' in order to get all the
other necessary information for the prompt even on an unborn branch.
Furthermore, in that case, and in that case only, 'git rev-parse'
doesn't output the last line containing the abbreviated commit object
name, obviously, so we have to take care to only parse it if 'git
rev-parse' exited without any error.
Although there are tests already excercising __git_ps1() on unborn
branches, they all do so implicitly. Add a test that checks this
explicitly.
Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 7d22625..88d6121 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -311,8 +311,12 @@
;;
esac
- local repo_info="$(git rev-parse --git-dir --is-inside-git-dir \
- --is-bare-repository --is-inside-work-tree 2>/dev/null)"
+ local repo_info rev_parse_exit_code
+ repo_info="$(git rev-parse --git-dir --is-inside-git-dir \
+ --is-bare-repository --is-inside-work-tree \
+ --short HEAD 2>/dev/null)"
+ rev_parse_exit_code="$?"
+
if [ -z "$repo_info" ]; then
if [ $pcmode = yes ]; then
#In PC mode PS1 always needs to be set
@@ -321,6 +325,11 @@
return
fi
+ local short_sha
+ if [ "$rev_parse_exit_code" = "0" ]; then
+ short_sha="${repo_info##*$'\n'}"
+ repo_info="${repo_info%$'\n'*}"
+ fi
local inside_worktree="${repo_info##*$'\n'}"
repo_info="${repo_info%$'\n'*}"
local bare_repo="${repo_info##*$'\n'}"
@@ -392,8 +401,7 @@
git describe --tags --exact-match HEAD ;;
esac 2>/dev/null)" ||
- b="$(git rev-parse --short HEAD 2>/dev/null)..." ||
- b="unknown"
+ b="$short_sha..."
b="($b)"
fi
fi
