@matheusbsbs / matheus-bagliano / commits / 3a43c4b5bd

bash prompt: use bash builtins to find out current branch

__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 <szeder@ira.uka.de>

SZEDER Gábor committed Mar 31, 2011 at 23:41 UTC 3a43c4b5bd19528229ef36b28d648d5ac98f15f1

1 file changed +33 -18

contrib/completion/git-prompt.sh

+33 -18

@@ -355,25 +355,40 @@ __git_ps1 ()

355 r="|BISECTING"

356 fi

357

358 - test -n "$b" ||

359 - b="$(git symbolic-ref HEAD 2>/dev/null)" || {

360 - detached=yes

361 - b="$(

362 - case "${GIT_PS1_DESCRIBE_STYLE-}" in

363 - (contains)

364 - git describe --contains HEAD ;;

365 - (branch)

366 - git describe --contains --all HEAD ;;

367 - (describe)

368 - git describe HEAD ;;

369 - (* | default)

370 - git describe --tags --exact-match HEAD ;;

371 - esac 2>/dev/null)" ||

358 + if [ -n "$b" ]; then

359 + :

360 + elif [ -h "$g/HEAD" ]; then

361 + # symlink symbolic ref

362 + b="$(git symbolic-ref HEAD 2>/dev/null)"

363 + else

364 + local head=""

365 + if ! read head 2>/dev/null <"$g/HEAD"; then

366 + if [ $pcmode = yes ]; then

367 + PS1="$ps1pc_start$ps1pc_end"

368 + fi

369 + return

370 + fi

371 + # is it a symbolic ref?

372 + b="${head#ref: }"

373 + if [ "$head" = "$b" ]; then

374 + detached=yes

375 + b="$(

376 + case "${GIT_PS1_DESCRIBE_STYLE-}" in

377 + (contains)

378 + git describe --contains HEAD ;;

379 + (branch)

380 + git describe --contains --all HEAD ;;

381 + (describe)

382 + git describe HEAD ;;

383 + (* | default)

384 + git describe --tags --exact-match HEAD ;;

385 + esac 2>/dev/null)" ||

386

373 - b="$(git rev-parse --short HEAD 2>/dev/null)..." ||

374 - b="unknown"

375 - b="($b)"

376 - }

387 + b="$(git rev-parse --short HEAD 2>/dev/null)..." ||

388 + b="unknown"

389 + b="($b)"

390 + fi

391 + fi

392 fi

393

394 if [ -n "$step" ] && [ -n "$total" ]; then