Merge branch 'program-data-config'

This branch introduces support for reading the "Windows-wide" Git
configuration from `%PROGRAMDATA%\Git\config`. As these settings are
intended to be shared between *all* Git-related software, that config
file takes an even lower precedence than `$(prefix)/etc/gitconfig`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Documentation/config.txt

@@ -7,7 +7,9 @@ the Git commands' behavior. The files `.git/config` and optionally
 repository are used to store the configuration for that repository, and
 `$HOME/.gitconfig` is used to store a per-user configuration as
 fallback values for the `.git/config` file. The file `/etc/gitconfig`
-can be used to store a system-wide default configuration.
+can be used to store a system-wide default configuration. On Windows,
+configuration can also be stored in `C:\ProgramData\Git\config`; This
+file will be used also by libgit2-based software.
 
 The configuration variables are used by both the Git plumbing
 and the porcelains. The variables are divided into sections, wherein

Documentation/git-config.txt

@@ -272,8 +272,16 @@ FILES
 If not set explicitly with `--file`, there are four files where
 'git config' will search for configuration options:
 
+$PROGRAMDATA/Git/config::
+	(Windows-only) System-wide configuration file shared with other Git
+	implementations. Typically `$PROGRAMDATA` points to `C:\ProgramData`.
+
 $(prefix)/etc/gitconfig::
 	System-wide configuration file.
+	(Windows-only) This file contains only the settings which are
+	specific for this installation of Git for Windows and which should
+	not be shared with other Git implementations like JGit, libgit2.
+	`--system` will select this file.
 
 $XDG_CONFIG_HOME/git/config::
 	Second user-specific configuration file. If $XDG_CONFIG_HOME is not set

Documentation/git.txt

@@ -566,7 +566,8 @@ for further details.
 
 `GIT_CONFIG_NOSYSTEM`::
 	Whether to skip reading settings from the system-wide
-	`$(prefix)/etc/gitconfig` file.  This environment variable can
+	`$(prefix)/etc/gitconfig` file (and on Windows, also from the
+	`%PROGRAMDATA%\Git\config` file).  This environment variable can
 	be used along with `$HOME` and `$XDG_CONFIG_HOME` to create a
 	predictable environment for a picky script, or you can set it
 	temporarily to avoid using a buggy `/etc/gitconfig` file while

compat/mingw.c

@@ -2540,3 +2540,17 @@ int uname(struct utsname *buf)
 		  "%u", (v >> 16) & 0x7fff);
 	return 0;
 }
+
+const char *program_data_config(void)
+{
+	static struct strbuf path = STRBUF_INIT;
+	static unsigned initialized;
+
+	if (!initialized) {
+		const char *env = mingw_getenv("PROGRAMDATA");
+		if (env)
+			strbuf_addf(&path, "%s/Git/config", env);
+		initialized = 1;
+	}
+	return *path.buf ? path.buf : NULL;
+}

compat/mingw.h

@@ -445,6 +445,8 @@ static inline void convert_slashes(char *path)
 #define PATH_SEP ';'
 extern char *mingw_query_user_email(void);
 #define query_user_email mingw_query_user_email
+extern const char *program_data_config(void);
+#define git_program_data_config program_data_config
 #if !defined(__MINGW64_VERSION_MAJOR) && (!defined(_MSC_VER) || _MSC_VER < 1800)
 #define PRIuMAX "I64u"
 #define PRId64 "I64d"

config.c

@@ -1676,11 +1676,16 @@ static int do_git_config_sequence(const struct config_options *opts,
 		repo_config = NULL;
 
 	current_parsing_scope = CONFIG_SCOPE_SYSTEM;
-	if (git_config_system() && !access_or_die(git_etc_gitconfig(), R_OK,
-						  opts->system_gently ?
-						  ACCESS_EACCES_OK : 0))
-		ret += git_config_from_file(fn, git_etc_gitconfig(),
-					    data);
+	if (git_config_system()) {
+		int flags = opts->system_gently ? ACCESS_EACCES_OK : 0;
+		const char *program_data = git_program_data_config();
+		const char *etc = git_etc_gitconfig();
+
+		if (program_data && !access_or_die(program_data, R_OK, flags))
+			ret += git_config_from_file(fn, program_data, data);
+		if (!access_or_die(etc, R_OK, flags))
+			ret += git_config_from_file(fn, etc, data);
+	}
 
 	current_parsing_scope = CONFIG_SCOPE_GLOBAL;
 	if (xdg_config && !access_or_die(xdg_config, R_OK, ACCESS_EACCES_OK))

git-compat-util.h

@@ -421,6 +421,10 @@ static inline char *git_find_last_dir_sep(const char *path)
 #endif
 #endif
 
+#ifndef git_program_data_config
+#define git_program_data_config() NULL
+#endif
+
 #if defined(__HP_cc) && (__HP_cc >= 61000)
 #define NORETURN __attribute__((noreturn))
 #define NORETURN_PTR