[PATCHv3 09/16] bash prompt: use bash builtins to find out current branch
From: SZEDER Gábor <hidden>
Date: 2016-06-15 22:57:54
Subsystem:
the rest · Maintainer:
Linus Torvalds
__git_ps1() runs the '$(git symbolic-ref HEAD)' command substitution to find out whether we are on a branch and to find out the name of that branch. This imposes the overhead of fork()ing a subshell and fork()+exec()ing a git process. Since HEAD is in most cases a single-line file and the symbolic ref format is quite simple to recognize and parse, read and parse it using only bash builtins, thereby sparing all that fork()+exec() overhead. Don't display the git prompt if reading HEAD fails, because a readable HEAD is required for a git repository. HEAD can also be a symlink symbolic ref (due to 'core.preferSymlinkRefs'), so use bash builtins for reading HEAD only when HEAD is not a symlink. Signed-off-by: SZEDER Gábor <redacted> --- contrib/completion/git-prompt.sh | 51 ++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 18 deletions(-)
diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index bc402f56..c2050b69 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh@@ -355,25 +355,40 @@ __git_ps1 () r="|BISECTING" fi - test -n "$b" || - b="$(git symbolic-ref HEAD 2>/dev/null)" || { - detached=yes - b="$( - case "${GIT_PS1_DESCRIBE_STYLE-}" in - (contains) - git describe --contains HEAD ;; - (branch) - git describe --contains --all HEAD ;; - (describe) - git describe HEAD ;; - (* | default) - git describe --tags --exact-match HEAD ;; - esac 2>/dev/null)" || + if [ -n "$b" ]; then + : + elif [ -h "$g/HEAD" ]; then + # symlink symbolic ref + b="$(git symbolic-ref HEAD 2>/dev/null)" + else + local head="" + if ! read head 2>/dev/null <"$g/HEAD"; then + if [ $pcmode = yes ]; then + PS1="$ps1pc_start$ps1pc_end" + fi + return + fi + # is it a symbolic ref? + b="${head#ref: }" + if [ "$head" = "$b" ]; then + detached=yes + b="$( + case "${GIT_PS1_DESCRIBE_STYLE-}" in + (contains) + git describe --contains HEAD ;; + (branch) + git describe --contains --all HEAD ;; + (describe) + git describe HEAD ;; + (* | default) + git describe --tags --exact-match HEAD ;; + esac 2>/dev/null)" || - b="$(git rev-parse --short HEAD 2>/dev/null)..." || - b="unknown" - b="($b)" - } + b="$(git rev-parse --short HEAD 2>/dev/null)..." || + b="unknown" + b="($b)" + fi + fi fi if [ -n "$step" ] && [ -n "$total" ]; then
--
1.8.3.1.599.g4459181