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From: Christian Couder <christian.couder@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Karsten Blees" <karsten.blees@gmail.com>,
	"Nguyen Thai Ngoc Duy" <pclouds@gmail.com>,
	"Stefan Beller" <sbeller@google.com>,
	"Eric Sunshine" <sunshine@sunshineco.com>,
	"Ramsay Jones" <ramsay@ramsayjones.plus.com>,
	"Johannes Sixt" <j6t@kdbg.org>, "René Scharfe" <l.s.r@web.de>,
	"Christian Couder" <chriscool@tuxfamily.org>
Subject: [PATCH v10 33/40] environment: add set_index_file()
Date: Mon,  8 Aug 2016 23:03:30 +0200	[thread overview]
Message-ID: <20160808210337.5038-34-chriscool@tuxfamily.org> (raw)
In-Reply-To: <20160808210337.5038-1-chriscool@tuxfamily.org>

Introduce set_index_file() to be able to temporarily change the
index file.

Yeah, this is a short cut and this new function should not be used
by other code.

It adds a small technical debt, because unfortunately a very big
technical debt already exists as the apply code and a lot of other
"libified" code already call functions like read_cache(),
discard_cache() and cache_name_pos() instead of functions like
read_index_from(), discard_index() and index_name_pos() that are
available when the NO_THE_INDEX_COMPATIBILITY_MACROS env variable
is defined.

Avoiding this small new technical debt is unfortunately not as simple
as just changing these functions in "apply.c", as these functions can
be called by other "libified" code that can indirectly be called by
apply code.

For example cache_name_pos() is used in "dir.c" and "diff.c", and then
"dir.h" and "diff.h" are included in many other "libified" *.c files
(including "apply.c"). So it is very difficult to make sure that apply
code doesn't indirectly call any of the problematic functions.

And even if it was possible to make sure that now "apply.c" doesn't
indirectly call any of these functions, how could we make sure that
later a refactoring in other "libified" code will not change a
function that is indirectly called by "apply.c" to make it call another
function that indirectly calls a problematic function?

So it's a different project altogether to remove calls to problematic
functions (like read_cache(), discard_cache(), cache_name_pos() and so
on) in all the libified code, starting maybe with "dir.c" and "diff.c".

Now if someone really needs to use this new function, it should be
used like this:

    /* Save current index file */
    old_index_file = get_index_file();
    set_index_file((char *)tmp_index_file);

    /* Do stuff that will use tmp_index_file as the index file */
    ...

    /* When finished reset the index file */
    set_index_file(old_index_file);

It is intended to be used by builtins commands, in fact only `git am`,
to temporarily change the index file used by libified code.

This is useful when libified code uses the global index, but a builtin
command wants another index file to be used instead.

Helped-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 cache.h       | 13 +++++++++++++
 environment.c | 16 ++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/cache.h b/cache.h
index b5f76a4..c9ad7f9 100644
--- a/cache.h
+++ b/cache.h
@@ -471,6 +471,19 @@ extern const char *strip_namespace(const char *namespaced_ref);
 extern const char *get_git_work_tree(void);
 
 /*
+ * Hack to temporarily change the index.
+ * Yeah, the libification of 'apply' took a short-circuit by adding
+ * this technical debt.
+ * Please use functions available when
+ * NO_THE_INDEX_COMPATIBILITY_MACROS is defined, instead of this
+ * function.
+ * If you really need to use this function, please save the current
+ * index file using get_index_file() before changing the index
+ * file. And when finished, reset it to the saved value.
+ */
+extern void set_index_file(char *index_file);
+
+/*
  * Return true if the given path is a git directory; note that this _just_
  * looks at the directory itself. If you want to know whether "foo/.git"
  * is a repository, you must feed that path, not just "foo".
diff --git a/environment.c b/environment.c
index ca72464..55b2b6b 100644
--- a/environment.c
+++ b/environment.c
@@ -292,6 +292,22 @@ int odb_pack_keep(char *name, size_t namesz, const unsigned char *sha1)
 	return open(name, O_RDWR|O_CREAT|O_EXCL, 0600);
 }
 
+/*
+ * Hack to temporarily change the index.
+ * Yeah, the libification of 'apply' took a short-circuit by adding
+ * this technical debt.
+ * Please use functions available when
+ * NO_THE_INDEX_COMPATIBILITY_MACROS is defined, instead of this
+ * function.
+ * If you really need to use this function, please save the current
+ * index file using get_index_file() before changing the index
+ * file. And when finished, reset it to the saved value.
+ */
+void set_index_file(char *index_file)
+{
+	git_index_file = index_file;
+}
+
 char *get_index_file(void)
 {
 	if (!git_index_file)
-- 
2.9.2.614.g4980f51


  parent reply	other threads:[~2016-08-08 21:05 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-08 21:02 [PATCH v10 00/40] libify apply and use lib in am, part 2 Christian Couder
2016-08-08 21:02 ` [PATCH v10 01/40] apply: make some names more specific Christian Couder
2016-08-09 14:51   ` stefan.naewe
2016-08-11  8:40     ` Christian Couder
2016-08-11  8:55       ` stefan.naewe
2016-08-08 21:02 ` [PATCH v10 02/40] apply: move 'struct apply_state' to apply.h Christian Couder
2016-08-08 21:03 ` [PATCH v10 03/40] builtin/apply: make apply_patch() return -1 or -128 instead of die()ing Christian Couder
2016-08-08 21:03 ` [PATCH v10 04/40] builtin/apply: read_patch_file() return -1 " Christian Couder
2016-08-08 21:03 ` [PATCH v10 05/40] builtin/apply: make find_header() return -128 " Christian Couder
2016-08-08 21:03 ` [PATCH v10 06/40] builtin/apply: make parse_chunk() return a negative integer on error Christian Couder
2016-08-08 21:03 ` [PATCH v10 07/40] builtin/apply: make parse_single_patch() return -1 " Christian Couder
2016-08-08 21:03 ` [PATCH v10 08/40] builtin/apply: make parse_whitespace_option() return -1 instead of die()ing Christian Couder
2016-08-08 21:03 ` [PATCH v10 09/40] builtin/apply: make parse_ignorewhitespace_option() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 10/40] builtin/apply: move init_apply_state() to apply.c Christian Couder
2016-08-08 21:03 ` [PATCH v10 11/40] apply: make init_apply_state() return -1 instead of exit()ing Christian Couder
2016-08-08 21:03 ` [PATCH v10 12/40] builtin/apply: make check_apply_state() return -1 instead of die()ing Christian Couder
2016-08-08 21:03 ` [PATCH v10 13/40] builtin/apply: move check_apply_state() to apply.c Christian Couder
2016-08-08 21:03 ` [PATCH v10 14/40] builtin/apply: make apply_all_patches() return 128 or 1 on error Christian Couder
2016-08-08 21:03 ` [PATCH v10 15/40] builtin/apply: make parse_traditional_patch() return -1 " Christian Couder
2016-08-08 21:03 ` [PATCH v10 16/40] builtin/apply: make gitdiff_*() return 1 at end of header Christian Couder
2016-08-08 21:03 ` [PATCH v10 17/40] builtin/apply: make gitdiff_*() return -1 on error Christian Couder
2016-08-08 21:03 ` [PATCH v10 18/40] builtin/apply: change die_on_unsafe_path() to check_unsafe_path() Christian Couder
2016-08-08 21:03 ` [PATCH v10 19/40] builtin/apply: make build_fake_ancestor() return -1 on error Christian Couder
2016-08-08 21:03 ` [PATCH v10 20/40] builtin/apply: make remove_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 21/40] builtin/apply: make add_conflicted_stages_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 22/40] builtin/apply: make add_index_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 23/40] builtin/apply: make create_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 24/40] builtin/apply: make write_out_one_result() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 25/40] builtin/apply: make write_out_results() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 26/40] builtin/apply: make try_create_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 27/40] builtin/apply: make create_one_file() " Christian Couder
2016-08-08 21:03 ` [PATCH v10 28/40] builtin/apply: rename option parsing functions Christian Couder
2016-08-09 14:55   ` stefan.naewe
2016-08-08 21:03 ` [PATCH v10 29/40] apply: rename and move opt constants to apply.h Christian Couder
2016-08-08 21:03 ` [PATCH v10 31/40] apply: make some parsing functions static again Christian Couder
2016-08-08 21:03 ` [PATCH v10 32/40] apply: use error_errno() where possible Christian Couder
2016-08-08 21:03 ` Christian Couder [this message]
2016-08-08 22:13   ` [PATCH v10 33/40] environment: add set_index_file() Junio C Hamano
2016-08-10 16:52     ` Christian Couder
2016-08-10 17:34       ` Junio C Hamano
2016-08-11 19:08         ` Christian Couder
2016-08-11 19:30           ` Junio C Hamano
2016-08-08 21:03 ` [PATCH v10 34/40] apply: make it possible to silently apply Christian Couder
2016-08-08 21:03 ` [PATCH v10 35/40] apply: don't print on stdout in verbosity_silent mode Christian Couder
2016-08-08 21:03 ` [PATCH v10 36/40] usage: add set_warn_routine() Christian Couder
2016-08-08 21:03 ` [PATCH v10 37/40] usage: add get_error_routine() and get_warn_routine() Christian Couder
2016-08-08 21:03 ` [PATCH v10 38/40] apply: change error_routine when silent Christian Couder
2016-08-08 21:03 ` [PATCH v10 39/40] apply: refactor `git apply` option parsing Christian Couder
2016-08-08 21:03 ` [PATCH v10 40/40] builtin/am: use apply api in run_apply() Christian Couder
2016-08-08 21:23 ` [PATCH v10 00/40] libify apply and use lib in am, part 2 Christian Couder
2016-08-08 22:16   ` Junio C Hamano

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