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Heiko Voigt c755015f79 help: improve is_executable() on Windows
On Windows, executables need to have the file extension `.exe`, or they
are not executables. Hence, to support scripts, Git for Windows also
looks for a she-bang line by opening the file in question, and executing
it via the specified script interpreter.

To figure out whether files in the `PATH` are executable, `git help` has
code that imitates this behavior. With one exception: it *always* opens
the files and looks for a she-bang line *or* an `MZ` tell-tale
(nevermind that files with the magic `MZ` but without file extension
`.exe` would still not be executable).

Opening this many files leads to performance problems that are even more
serious when a virus scanner is running. Therefore, let's change the
code to look for the file extension `.exe` early, and avoid opening the
file altogether if we already know that it is executable.

See the following measurements (in seconds) as an example, where we
execute a simple program that simply lists the directory contents and
calls open() on every listed file:

With virus scanner running (coldcache):

$ ./a.exe /libexec/git-core/
before open (git-add.exe): 0.000000
after open (git-add.exe): 0.412873
before open (git-annotate.exe): 0.000175
after open (git-annotate.exe): 0.397925
before open (git-apply.exe): 0.000243
after open (git-apply.exe): 0.399996
before open (git-archive.exe): 0.000147
after open (git-archive.exe): 0.397783
before open (git-bisect--helper.exe): 0.000160
after open (git-bisect--helper.exe): 0.397700
before open (git-blame.exe): 0.000160
after open (git-blame.exe): 0.399136
...

With virus scanner running (hotcache):

$ ./a.exe /libexec/git-core/
before open (git-add.exe): 0.000000
after open (git-add.exe): 0.000325
before open (git-annotate.exe): 0.000229
after open (git-annotate.exe): 0.000177
before open (git-apply.exe): 0.000167
after open (git-apply.exe): 0.000150
before open (git-archive.exe): 0.000154
after open (git-archive.exe): 0.000156
before open (git-bisect--helper.exe): 0.000132
after open (git-bisect--helper.exe): 0.000180
before open (git-blame.exe): 0.000718
after open (git-blame.exe): 0.000724
...

With this patch I get:

$ time git help git
Launching default browser to display HTML ...

real    0m8.723s
user    0m0.000s
sys     0m0.000s

and without

$ time git help git
Launching default browser to display HTML ...

real    1m37.734s
user    0m0.000s
sys     0m0.031s

both tests with cold cache and giving the machine some time to settle
down after restart.

[jes: adjusted the commit message]

Signed-off-by: Heiko Voigt <heiko.voigt@mahr.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-30 09:04:17 -08:00
Documentation Almost ready for 2.11.1 2017-01-17 15:19:11 -08:00
block-sha1
builtin Merge branch 'jt/fetch-no-redundant-tag-fetch-map' into maint 2017-01-17 15:19:09 -08:00
ci
compat Merge branch 'mk/mingw-winansi-ttyname-termination-fix' into maint 2017-01-17 15:19:03 -08:00
contrib Merge branch 'ls/filter-process' into maint 2017-01-17 15:19:08 -08:00
ewah
git-gui git-gui 0.21.0 2016-10-20 09:33:17 -07:00
gitk-git
gitweb Merge branch 'ab/gitweb-abbrev-links' 2016-10-26 13:14:46 -07:00
mergetools Merge branch 'da/mergetool-xxdiff-hotkey' into maint 2017-01-17 15:11:05 -08:00
perl Merge branch 'mm/send-email-cc-cruft-after-address' into maint 2016-11-29 13:27:55 -08:00
po Merge branch 'russian-l10n' of https://github.com/DJm00n/git-po-ru 2016-11-29 21:19:43 +08:00
ppc
refs Merge branch 'jk/ref-symlink-loop' 2016-10-17 13:25:20 -07:00
t Merge branch 'ls/filter-process' into maint 2017-01-17 15:19:08 -08:00
templates pre-receive.sample: mark it executable 2016-10-28 14:21:11 -07:00
vcs-svn
xdiff
.gitattributes
.gitignore Merge branch 'bb/unicode-9.0' into maint 2017-01-17 14:49:25 -08:00
.mailmap
.travis.yml travis-ci: update P4 to 16.2 and GitLFS to 1.5.2 in Linux build 2016-12-05 14:55:52 -08:00
COPYING
GIT-VERSION-GEN Almost ready for 2.11.1 2017-01-17 15:19:11 -08:00
INSTALL
LGPL-2.1
Makefile Merge branch 'ls/macos-update' into maint 2016-11-29 13:27:56 -08:00
README.md README: replace gmane link with public-inbox 2016-12-15 09:30:09 -08:00
RelNotes Almost ready for 2.11.1 2017-01-17 15:19:11 -08:00
abspath.c
aclocal.m4
advice.c
advice.h
alias.c
alloc.c
apply.c i18n: apply: mark error message for translation 2016-10-17 14:51:42 -07:00
apply.h
archive-tar.c
archive-zip.c
archive.c archive: read local configuration 2016-11-22 13:55:20 -08:00
archive.h archive: read local configuration 2016-11-22 13:55:20 -08:00
argv-array.c
argv-array.h
attr.c read info/{attributes,exclude} only when in repository 2016-10-26 13:30:51 -07:00
attr.h
base85.c
bisect.c
bisect.h
blob.c
blob.h
branch.c worktree.c: get_worktrees() takes a new flag argument 2016-11-28 13:18:51 -08:00
branch.h create_branch: drop unused "head" parameter 2016-11-09 14:56:21 -08:00
builtin.h
bulk-checkin.c
bulk-checkin.h
bundle.c
bundle.h
cache-tree.c
cache-tree.h
cache.h Merge branch 'ls/git-open-cloexec' 2016-10-31 13:15:21 -07:00
check-builtins.sh
check-racy.c
check_bindir
color.c
color.h
column.c
column.h
combine-diff.c diff_aligned_abbrev: use "struct oid" 2016-10-26 13:30:51 -07:00
command-list.txt
commit-slab.h
commit.c Merge branch 'rs/copy-array' into maint 2016-10-11 14:18:32 -07:00
commit.h Merge branch 'nd/shallow-deepen' 2016-10-10 14:03:50 -07:00
common-main.c common-main: stop munging argv[0] path 2016-11-29 11:01:48 -08:00
config.c
config.mak.in
config.mak.uname
configure.ac Merge branch 'dp/autoconf-curl-ssl' into maint 2016-10-28 09:01:13 -07:00
connect.c Merge branch 'ls/filter-process' 2016-10-31 13:15:21 -07:00
connect.h
connected.c check_connected: accept an env argument 2016-10-10 13:54:02 -07:00
connected.h check_connected: accept an env argument 2016-10-10 13:54:02 -07:00
convert.c Merge branch 'jc/renormalize-merge-kill-safer-crlf' into maint 2017-01-17 14:49:28 -08:00
convert.h
copy.c
credential-cache--daemon.c i18n: credential-cache--daemon: mark advice for translation 2016-10-17 14:51:47 -07:00
credential-cache.c
credential-store.c
credential.c
credential.h
csum-file.c
csum-file.h
ctype.c
daemon.c Merge branch 'jk/daemon-path-ok-check-truncation' into maint 2016-11-29 13:27:56 -08:00
date.c
decorate.c
decorate.h
delta.h
diff-delta.c
diff-lib.c commit: fix empty commit creation when there's no changes but ita entries 2016-10-24 10:48:23 -07:00
diff-no-index.c
diff.c diff: handle --no-abbrev in no-index case 2016-12-08 14:40:30 -08:00
diff.h Merge branch 'nd/ita-empty-commit' 2016-10-27 14:58:50 -07:00
diffcore-break.c Merge branch 'tk/diffcore-delta-remove-unused' into maint 2016-11-29 13:28:03 -08:00
diffcore-delta.c Merge branch 'tk/diffcore-delta-remove-unused' 2016-11-17 13:45:22 -08:00
diffcore-order.c
diffcore-pickaxe.c
diffcore-rename.c Merge branch 'tk/diffcore-delta-remove-unused' into maint 2016-11-29 13:28:03 -08:00
diffcore.h Merge branch 'tk/diffcore-delta-remove-unused' into maint 2016-11-29 13:28:03 -08:00
dir-iterator.c
dir-iterator.h
dir.c read info/{attributes,exclude} only when in repository 2016-10-26 13:30:51 -07:00
dir.h ls-files: add pathspec matching for submodules 2016-10-10 12:14:58 -07:00
editor.c
entry.c
environment.c Merge branch 'lt/abbrev-auto' 2016-10-27 14:58:47 -07:00
exec_cmd.c common-main: stop munging argv[0] path 2016-11-29 11:01:48 -08:00
exec_cmd.h common-main: stop munging argv[0] path 2016-11-29 11:01:48 -08:00
fast-import.c
fetch-pack.c fetch-pack.c: correct command at the beginning of an error message 2016-11-11 13:28:39 -08:00
fetch-pack.h
fmt-merge-msg.h
fsck.c
fsck.h
generate-cmdlist.sh
gettext.c
gettext.h
git-add--interactive.perl
git-archimport.perl
git-bisect.sh
git-compat-util.h Merge branch 'jk/common-main' into maint-2.10 2016-12-05 11:24:28 -08:00
git-cvsexportcommit.perl
git-cvsimport.perl
git-cvsserver.perl
git-difftool--helper.sh
git-difftool.perl Merge branch 'jk/difftool-in-subdir' into maint 2017-01-17 15:14:40 -08:00
git-filter-branch.sh
git-instaweb.sh
git-merge-octopus.sh
git-merge-one-file.sh
git-merge-resolve.sh
git-mergetool--lib.sh mergetool: honor mergetool.$tool.trustExitCode for built-in tools 2016-11-29 10:54:03 -08:00
git-mergetool.sh mergetool: honor -O<orderfile> 2016-10-11 10:04:31 -07:00
git-p4.py Merge branch 'gv/p4-multi-path-commit-fix' into maint 2017-01-17 15:19:02 -08:00
git-parse-remote.sh
git-quiltimport.sh
git-rebase--am.sh
git-rebase--interactive.sh Merge branch 'js/rebase-i-commentchar-fix' 2016-11-23 11:23:17 -08:00
git-rebase--merge.sh
git-rebase.sh
git-relink.perl
git-remote-testgit.sh
git-request-pull.sh
git-send-email.perl
git-sh-i18n.sh
git-sh-setup.sh git-sh-setup: be explicit where to dot-source git-sh-i18n from. 2016-10-30 16:13:49 -07:00
git-stash.sh Merge branch 'jk/stash-disable-renames-internally' into maint 2017-01-17 14:49:30 -08:00
git-submodule.sh
git-svn.perl git-svn: "git worktree" awareness 2016-10-14 01:36:12 +00:00
git-web--browse.sh
git.c Merge branch 'jk/common-main' into maint-2.10 2016-12-05 11:24:28 -08:00
git.rc
gpg-interface.c gpg-interface: use more status letters 2016-10-12 10:41:59 -07:00
gpg-interface.h
graph.c Merge branch 'jk/graph-padding-fix' into maint 2016-10-11 14:19:03 -07:00
graph.h
grep.c
grep.h
hashmap.c
hashmap.h
help.c help: improve is_executable() on Windows 2017-01-30 09:04:17 -08:00
help.h
hex.c hex: make wraparound of the index into ring-buffer explicit 2016-10-26 10:54:11 -07:00
http-backend.c pkt-line: rename packet_write() to packet_write_fmt() 2016-10-17 11:36:50 -07:00
http-fetch.c
http-push.c
http-walker.c http-walker: complain about non-404 loose object errors 2016-12-06 12:43:34 -08:00
http.c Merge branch 'jk/http-walker-limit-redirect' into maint 2017-01-17 14:49:29 -08:00
http.h Merge branch 'jk/http-walker-limit-redirect' into maint 2017-01-17 14:49:29 -08:00
ident.c
imap-send.c Merge branch 'jc/cocci-xstrdup-or-null' into maint 2016-10-28 09:01:23 -07:00
iterator.h
khash.h
kwset.c
kwset.h
levenshtein.c
levenshtein.h
line-log.c
line-log.h
line-range.c
line-range.h
list-objects.c
list-objects.h
list.h
ll-merge.c
ll-merge.h
lockfile.c
lockfile.h
log-tree.c
log-tree.h
mailinfo.c Merge branch 'jt/mailinfo-fold-in-body-headers' into maint 2017-01-17 15:11:06 -08:00
mailinfo.h
mailmap.c cocci: refactor common patterns to use xstrdup_or_null() 2016-10-12 11:22:10 -07:00
mailmap.h
match-trees.c
merge-blobs.c
merge-blobs.h
merge-recursive.c Merge branch 'nd/qsort-in-merge-recursive' into maint 2017-01-17 15:19:03 -08:00
merge-recursive.h
merge.c
mergesort.c
mergesort.h
mru.c
mru.h
name-hash.c
notes-cache.c
notes-cache.h
notes-merge.c
notes-merge.h
notes-utils.c
notes-utils.h
notes.c
notes.h
object.c
object.h
pack-bitmap-write.c
pack-bitmap.c sha1_file: rename git_open_noatime() to git_open() 2016-10-25 10:59:13 -07:00
pack-bitmap.h
pack-check.c Merge branch 'jk/verify-packfile-gently' into maint 2016-10-11 14:21:36 -07:00
pack-objects.c
pack-objects.h
pack-revindex.c
pack-revindex.h
pack-write.c
pack.h
pager.c
parse-options-cb.c Merge branch 'rs/cocci' 2016-10-17 13:25:21 -07:00
parse-options.c parse-options: print "fatal:" before usage_msg_opt() 2016-12-14 09:58:09 -08:00
parse-options.h
patch-delta.c
patch-ids.c
patch-ids.h
path.c Merge branch 'js/normalize-path-copy-ceil' into maint 2017-01-17 15:11:03 -08:00
pathspec.c Merge branch 'ex/deprecate-empty-pathspec-as-match-all' 2016-10-26 13:14:56 -07:00
pathspec.h
pkt-line.c pkt-line: add functions to read/write flush terminated packet streams 2016-10-17 11:36:50 -07:00
pkt-line.h pkt-line: add functions to read/write flush terminated packet streams 2016-10-17 11:36:50 -07:00
preload-index.c
pretty.c Merge branch 'rs/cocci' into maint 2016-10-28 09:01:23 -07:00
prio-queue.c
prio-queue.h
progress.c
progress.h
prompt.c
prompt.h
quote.c
quote.h
reachable.c
reachable.h
read-cache.c read-cache: make sure file handles are not inherited by child processes 2016-10-25 11:10:18 -07:00
ref-filter.c Merge branch 'jc/for-each-ref-head-segfault-fix' 2016-11-23 11:23:16 -08:00
ref-filter.h
reflog-walk.c
reflog-walk.h
refs.c Merge branch 'jc/cocci-xstrdup-or-null' 2016-10-26 13:14:45 -07:00
refs.h Merge branch 'nd/shallow-deepen' 2016-10-10 14:03:50 -07:00
remote-curl.c Merge branch 'dt/smart-http-detect-server-going-away' into maint 2017-01-17 15:19:03 -08:00
remote-testsvn.c
remote.c
remote.h
replace_object.c
rerere.c
rerere.h
resolve-undo.c
resolve-undo.h
revision.c Merge branch 'vn/revision-shorthand-for-side-branch-log' 2016-10-06 14:53:10 -07:00
revision.h
run-command.c run-command: add clean_on_exit_handler 2016-10-17 11:36:50 -07:00
run-command.h run-command: add clean_on_exit_handler 2016-10-17 11:36:50 -07:00
send-pack.c cocci: refactor common patterns to use xstrdup_or_null() 2016-10-12 11:22:10 -07:00
send-pack.h
sequencer.c Revert "sequencer: remove useless get_dir() function" 2016-12-14 14:56:46 -08:00
sequencer.h sequencer: get rid of the subcommand field 2016-10-21 09:32:34 -07:00
server-info.c
setup.c
sh-i18n--envsubst.c
sha1-array.c Merge branch 'rs/qsort' 2016-10-10 14:03:46 -07:00
sha1-array.h
sha1-lookup.c
sha1-lookup.h
sha1_file.c Merge branch 'jk/quote-env-path-list-component' into maint 2017-01-17 15:11:06 -08:00
sha1_name.c Merge branch 'jk/no-looking-at-dotgit-outside-repo' 2016-11-01 12:58:49 -07:00
shallow.c Merge branch 'nd/shallow-fixup' into maint 2017-01-17 15:11:05 -08:00
shell.c
shortlog.h
show-index.c
sideband.c
sideband.h
sigchain.c
sigchain.h
split-index.c split-index: s/eith/with/ typo fix 2016-11-01 11:48:02 -07:00
split-index.h
strbuf.c link_alt_odb_entry: handle normalize_path errors 2016-10-10 13:52:36 -07:00
strbuf.h link_alt_odb_entry: handle normalize_path errors 2016-10-10 13:52:36 -07:00
streaming.c Merge branch 'jk/pack-objects-optim-mru' 2016-10-10 14:03:47 -07:00
streaming.h
string-list.c
string-list.h
submodule-config.c
submodule-config.h
submodule.c Merge branch 'bw/push-dry-run' into maint 2017-01-17 14:49:27 -08:00
submodule.h push: fix --dry-run to not push submodules 2016-11-23 08:39:14 -08:00
symlinks.c
tag.c
tag.h
tar.h
tempfile.c
tempfile.h
thread-utils.c
thread-utils.h
tmp-objdir.c tmp-objdir: quote paths we add to alternates 2016-12-12 15:10:46 -08:00
tmp-objdir.h tmp-objdir: introduce API for temporary object directories 2016-10-10 13:54:02 -07:00
trace.c
trace.h
trailer.c Merge branch 'jt/trailer-with-cruft' 2016-10-31 13:15:22 -07:00
trailer.h
transport-helper.c Merge branch 'nd/shallow-deepen' 2016-10-10 14:03:50 -07:00
transport.c Merge branch 'bw/push-dry-run' into maint 2017-01-17 14:49:27 -08:00
transport.h Merge branch 'jc/abbrev-auto' 2016-10-27 14:58:48 -07:00
tree-diff.c
tree-walk.c
tree-walk.h
tree.c
tree.h
unicode_width.h unicode_width.h: update the width tables to Unicode 9.0 2016-12-14 09:48:07 -08:00
unimplemented.sh
unix-socket.c
unix-socket.h
unpack-trees.c Merge branch 'sb/unpack-trees-grammofix' into maint 2017-01-17 15:19:05 -08:00
unpack-trees.h
upload-pack.c upload-pack: optionally allow fetching any sha1 2016-11-18 13:06:14 -08:00
url.c
url.h
urlmatch.c
urlmatch.h
usage.c
userdiff.c
userdiff.h
utf8.c
utf8.h
varint.c
varint.h
version.c
version.h
versioncmp.c
walker.c
walker.h
wildmatch.c
wildmatch.h
worktree.c worktree list: keep the list sorted 2016-11-28 13:18:51 -08:00
worktree.h worktree list: keep the list sorted 2016-11-28 13:18:51 -08:00
wrap-for-bin.sh
wrapper.c
write_or_die.c run-command: move check_pipe() from write_or_die to run_command 2016-10-17 11:36:49 -07:00
ws.c
wt-status.c Merge branch 'nd/ita-empty-commit' 2016-10-27 14:58:50 -07:00
wt-status.h wt-status: teach has_{unstaged,uncommitted}_changes() about submodules 2016-10-07 09:29:31 -07:00
xdiff-interface.c
xdiff-interface.h
zlib.c

README.md

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from http://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git, http://marc.info/?l=git and other archival sites.

The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):

  • random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
  • stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
  • "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
  • "goddamn idiotic truckload of sh*t": when it breaks