Christian Couder
cc4affc5ee
Some commands need to look at a few of their options before they can parse their command line for real, for example because the result decides whether a repository is needed at all, or how the beginning of their input should be interpreted. Such an early scan has to know which options take their value as a separate argument, or it mistakes such a value for an option. Several commands get this wrong, as they just walk their arguments comparing them to the few option names they care about. Let's add early_scan_options() to help with this. It walks the arguments using the very same `struct option` array that the command already passes to parse_options(). It looks up long options with the lookup_long_opt() helper extracted from parse_long_opt() in a previous commit, so that negated forms, unambiguous abbreviations and aliases are recognized the same way, and it uses the parse_options_takes_argument() helper added in another previous commit, so that the scan and the actual parsing agree on which options take a value. The options the caller wants to be told about are marked with a new PARSE_OPT_EARLY flag, so that nothing has to be spelled out a second time, and so that the mark cannot drift away from the option it refers to. Using a per-option flag for this is not new as that flag space already holds flags that the parsing loop itself ignores, like PARSE_OPT_NOCOMPLETE and PARSE_OPT_COMP_ARG, which only the completion helper looks at, or PARSE_OPT_HIDDEN and PARSE_OPT_LITERAL_ARGHELP, which only the usage output looks at. The scan is deliberately kept much simpler than parse_options(), instead of teaching the latter to perform a side effect free "dry run". Such a dry run would have to avoid writing through `opt->value`, calling option callbacks, dying on an invalid value, handling `--help` and tracking command mode conflicts, so it would be a much larger refactoring. If parse_options() learns to do it in the future though, the commands converted now would keep both their option array and their PARSE_OPT_EARLY marks, so their conversion would not have to be redone. One consequence of staying simple is that the scan doesn't try to handle what it cannot reliably skip, like short options, unknown options, ambiguous abbreviations or options with a low-level callback, which may consume any number of arguments. It stops at them instead, so that it never takes an option's value for an option. This matters, as for example with: git fast-import --quiet --export-pack --allow-unsafe-features parse_options() takes `--allow-unsafe-features` as the value of `--export-pack-edges`, which `--export-pack` abbreviates. A scan that just skipped `--export-pack` as an unknown option would wrongly see `--allow-unsafe-features` there. So the scan can fail to see an option that parse_options() would accept, but it doesn't report an option that parse_options() would not, and its callers can safely err on the side of not having seen an option. The differences with parse_options() are documented in "parse-options.h". In practice, despite these limitations, early scans using early_scan_options() should still be safer and cleaner than the ad-hoc hand-rolled scans they are meant to replace, which don't know about option values at all and therefore disagree with parse_options() in ways that create plain bugs. Helped-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com> Signed-off-by: Christian Couder <christian.couder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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 https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc 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.adoc
(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 and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
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Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
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