config --global --edit: create a template file if needed

When the user has no ~/.gitconfig file, git config --global --edit used
to launch an editor on an nonexistant file name.

Instead, create a file with a default content before launching the
editor. The template contains only commented-out entries, to save a few
keystrokes for the user. If the values are guessed properly, the user
will only have to uncomment the entries.

Advanced users teaching newbies can create a minimalistic configuration
faster for newbies. Beginners reading a tutorial advising to run "git
config --global --edit" as a first step will be slightly more guided for
their first contact with Git.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
home_config_paths(): let the caller ignore xdg path

The caller can signal that it is not interested in learning
the location of $HOME/.gitconfig by passing global=NULL, but
there is no way to decline the path to the configuration
file based on $XDG_CONFIG_HOME.

Allow the caller to pass xdg=NULL to signal that it is not
interested in the XDG location.

Commit-message-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit: advertise config --global --edit on guessed identity

When the user has no user-wide configuration file, it's faster to use the
newly introduced config file template than to run two commands to set
user.name and user.email. Advise this to the user.

The old advice is kept if the user already has a configuration file since
the template feature would not trigger in this case.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
strbuf: add strbuf_getcwd()

Add strbuf_getcwd(), which puts the current working directory into a
strbuf.  Because it doesn't use a fixed-size buffer it supports
arbitrarily long paths, provided the platform's getcwd() does as well.
At least on Linux and FreeBSD it handles paths longer than PATH_MAX
just fine.

Suggested-by: Karsten Blees <karsten.blees@gmail.com>
Helped-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
unix-sockets: use strbuf_getcwd()

Instead of using a PATH_MAX-sized buffer, which can be too small on some
file systems, use strbuf_getcwd(), which handles any path getcwd()
returns.  Also preserve the errno set by strbuf_getcwd() instead of
setting it to ENAMETOOLONG; that way a more appropriate error message
can be shown based on the actual reason for failing.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
setup: convert setup_git_directory_gently_1 et al. to strbuf

Convert setup_git_directory_gently_1() and its helper functions
setup_explicit_git_dir(), setup_discovered_git_dir() and
setup_bare_git_dir() to use a struct strbuf to hold the current working
directory.  Replacing the PATH_MAX-sized buffer used before removes a
path length limition on some file systems.  The functions are converted
all in one go because they all read and write the variable cwd.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
abspath: use strbuf_getcwd() to remember original working directory

Store the original working directory in a strbuf instead of in a
fixed-sized buffer, in order to be able to handle longer paths.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
init: avoid superfluous real_path() calls

Feeding the result of a real_path() call to real_path() again doesn't
change that result -- the returned path won't get any more real.  Avoid
such a double call in set_git_dir_init() and for the same reason stop
calling real_path() before feeding paths to set_git_work_tree(), as the
latter already takes care of that.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
abspath: convert real_path_internal() to strbuf

Use strbuf instead of fixed-sized buffers in real_path() in order to
avoid the size limitations of the latter.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
wrapper: add xgetcwd()

Add the helper function xgetcwd(), which returns the current directory
or dies.  The returned string has to be free()d after use.

Helped-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
use xgetcwd() to get the current directory or die

Convert several calls of getcwd() and die() to use xgetcwd() instead.
This way we get rid of fixed-size buffers (which can be too small
depending on the used file system) and gain consistent error messages.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
use xgetcwd() to set $GIT_DIR

Instead of dying of a segmentation fault if getcwd() returns NULL, use
xgetcwd() to make sure to write a useful error message and then exit
in an orderly fashion.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
abspath: convert absolute_path() to strbuf

Move most of the code of absolute_path() into the new function
strbuf_add_absolute_path() and in the process transform it to use
struct strbuf and xgetcwd() instead of a PATH_MAX-sized buffer,
which can be too small on some file systems.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
use strbuf_add_absolute_path() to add absolute paths

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
add documentation for writing config files

Replace TODO introduced in commit 9c3c22 with documentation
explaining Git config API functions for writing configuration
files.

Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-push: fix link in man page

Signed-off-by: Tony Finch <dot@dotat.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'rs/strbuf-getcwd' into next

* rs/strbuf-getcwd:
  use strbuf_add_absolute_path() to add absolute paths
  abspath: convert absolute_path() to strbuf
  use xgetcwd() to set $GIT_DIR
  use xgetcwd() to get the current directory or die
  wrapper: add xgetcwd()
  abspath: convert real_path_internal() to strbuf
  abspath: use strbuf_getcwd() to remember original working directory
  setup: convert setup_git_directory_gently_1 et al. to strbuf
  unix-sockets: use strbuf_getcwd()
  strbuf: add strbuf_getcwd()
Merge branch 'mm/config-edit-global' into next

* mm/config-edit-global:
  commit: advertise config --global --edit on guessed identity
  home_config_paths(): let the caller ignore xdg path
  config --global --edit: create a template file if needed
Merge branch 'rs/init-no-duplicate-real-path' into next

* rs/init-no-duplicate-real-path:
  init: avoid superfluous real_path() calls
Merge branch 'ta/doc-config' into next

* ta/doc-config:
  add documentation for writing config files