thodg/libgit2

diff --git a/include/git2/config.h b/include/git2/config.h
index 21d8a0b..a7d8974 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -61,6 +61,9 @@ typedef struct {
  * may be used on any `git_config` call to load the
  * global configuration file.
  *
+ * This method will not guess the path to the xdg compatible
+ * config file (.config/git/config).
+ *
  * @param global_config_path Buffer of GIT_PATH_MAX length to store the path
  * @return 0 if a global configuration file has been
  *	found. Its path will be stored in `buffer`.
@@ -68,6 +71,23 @@ typedef struct {
 GIT_EXTERN(int) git_config_find_global(char *global_config_path, size_t length);
 
 /**
+ * Locate the path to the global xdg compatible configuration file
+ *
+ * The xdg compatible configuration file is usually
+ * located in `$HOME/.config/git/config`.
+ *
+ * This method will try to guess the full path to that
+ * file, if the file exists. The returned path
+ * may be used on any `git_config` call to load the
+ * xdg compatible configuration file.
+ *
+ * @param xdg_config_path Buffer of GIT_PATH_MAX length to store the path
+ * @return 0 if a xdg compatible configuration file has been
+ *	found. Its path will be stored in `buffer`.
+ */
+GIT_EXTERN(int) git_config_find_xdg(char *xdg_config_path, size_t length);
+
+/**
  * Locate the path to the system configuration file
  *
  * If /etc/gitconfig doesn't exist, it will look for
diff --git a/src/config.c b/src/config.c
index e62dccf..b89c16b 100644
--- a/src/config.c
+++ b/src/config.c
@@ -451,8 +451,12 @@ int git_config_find_global_r(git_buf *path)
 {
 	int error = git_futils_find_global_file(path, GIT_CONFIG_FILENAME);
 
-	if (error == GIT_ENOTFOUND)
-		error = git_futils_find_global_file(path, GIT_CONFIG_FILENAME_ALT);
+	return error;
+}
+
+int git_config_find_xdg_r(git_buf *path)
+{
+	int error = git_futils_find_global_file(path, GIT_CONFIG_FILENAME_ALT);
 
 	return error;
 }
@@ -479,6 +483,28 @@ int git_config_find_global(char *global_config_path, size_t length)
 	return 0;
 }
 
+int git_config_find_xdg(char *xdg_config_path, size_t length)
+{
+	git_buf path  = GIT_BUF_INIT;
+	int ret = git_config_find_xdg_r(&path);
+
+	if (ret < 0) {
+		git_buf_free(&path);
+		return ret;
+	}
+
+	if (path.size >= length) {
+		git_buf_free(&path);
+		giterr_set(GITERR_NOMEMORY,
+			"Path is to long to fit on the given buffer");
+		return -1;
+	}
+
+	git_buf_copy_cstr(xdg_config_path, length, &path);
+	git_buf_free(&path);
+	return 0;
+}
+
 int git_config_find_system_r(git_buf *path)
 {
 	return git_futils_find_system_file(path, GIT_CONFIG_FILENAME_SYSTEM);
@@ -515,6 +541,9 @@ int git_config_open_default(git_config **out)
 	error = git_config_new(&cfg);
 
 	if (!error && !git_config_find_global_r(&buf))
+		error = git_config_add_file_ondisk(cfg, buf.ptr, 3);
+
+	if (!error && !git_config_find_xdg_r(&buf))
 		error = git_config_add_file_ondisk(cfg, buf.ptr, 2);
 
 	if (!error && !git_config_find_system_r(&buf))
diff --git a/src/config.h b/src/config.h
index 5475ef3..471b42d 100644
--- a/src/config.h
+++ b/src/config.h
@@ -24,6 +24,7 @@ struct git_config {
 };
 
 extern int git_config_find_global_r(git_buf *global_config_path);
+extern int git_config_find_xdg_r(git_buf *system_config_path);
 extern int git_config_find_system_r(git_buf *system_config_path);
 
 extern int git_config_parse_bool(int *out, const char *bool_string);
diff --git a/src/fileops.c b/src/fileops.c
index 8ccf063..763537a 100644
--- a/src/fileops.c
+++ b/src/fileops.c
@@ -7,6 +7,9 @@
 #include "common.h"
 #include "fileops.h"
 #include <ctype.h>
+#if GIT_WIN32
+#include "win32/findfile.h"
+#endif
 
 int git_futils_mkpath2file(const char *file_path, const mode_t mode)
 {
@@ -371,98 +374,59 @@ int git_futils_rmdir_r(const char *path, git_directory_removal_type removal_type
 	return error;
 }
 
-#ifdef GIT_WIN32
-struct win32_path {
-	wchar_t path[MAX_PATH];
-	DWORD len;
-};
-
-static int win32_expand_path(struct win32_path *s_root, const wchar_t *templ)
-{
-	s_root->len = ExpandEnvironmentStringsW(templ, s_root->path, MAX_PATH);
-	return s_root->len ? 0 : -1;
-}
-
-static int win32_find_file(git_buf *path, const struct win32_path *root, const char *filename)
-{
-	size_t len, alloc_len;
-	wchar_t *file_utf16 = NULL;
-	char file_utf8[GIT_PATH_MAX];
-
-	if (!root || !filename || (len = strlen(filename)) == 0)
-		return GIT_ENOTFOUND;
-
-	/* allocate space for wchar_t path to file */
-	alloc_len = root->len + len + 2;
-	file_utf16 = git__calloc(alloc_len, sizeof(wchar_t));
-	GITERR_CHECK_ALLOC(file_utf16);
-
-	/* append root + '\\' + filename as wchar_t */
-	memcpy(file_utf16, root->path, root->len * sizeof(wchar_t));
-
-	if (*filename == '/' || *filename == '\\')
-		filename++;
-
-	git__utf8_to_16(file_utf16 + root->len - 1, alloc_len, filename);
-
-	/* check access */
-	if (_waccess(file_utf16, F_OK) < 0) {
-		git__free(file_utf16);
-		return GIT_ENOTFOUND;
-	}
-
-	git__utf16_to_8(file_utf8, file_utf16);
-	git_path_mkposix(file_utf8);
-	git_buf_sets(path, file_utf8);
-
-	git__free(file_utf16);
-	return 0;
-}
-#endif
-
 int git_futils_find_system_file(git_buf *path, const char *filename)
 {
 #ifdef GIT_WIN32
-	struct win32_path root;
-
-	if (win32_expand_path(&root, L"%PROGRAMFILES%\\Git\\etc\\") < 0 ||
-		root.path[0] == L'%') /* i.e. no expansion happened */
-	{
-		giterr_set(GITERR_OS, "Cannot locate the system's Program Files directory");
-		return -1;
-	}
-
-	if (win32_find_file(path, &root, filename) < 0) {
-		giterr_set(GITERR_OS, "The system file '%s' doesn't exist", filename);
-		git_buf_clear(path);
-		return GIT_ENOTFOUND;
-	}
-
-	return 0;
+	// try to find git.exe/git.cmd on path
+	if (!win32_find_system_file_using_path(path, filename))
+		return 0;
 
+	// try to find msysgit installation path using registry
+	if (!win32_find_system_file_using_registry(path, filename))
+		return 0;
 #else
 	if (git_buf_joinpath(path, "/etc", filename) < 0)
 		return -1;
 
 	if (git_path_exists(path->ptr) == true)
 		return 0;
+#endif
 
 	git_buf_clear(path);
 	giterr_set(GITERR_OS, "The system file '%s' doesn't exist", filename);
 	return GIT_ENOTFOUND;
-#endif
 }
 
 int git_futils_find_global_file(git_buf *path, const char *filename)
 {
+	const char *home = getenv("HOME");
+
 #ifdef GIT_WIN32
 	struct win32_path root;
 
-	if (win32_expand_path(&root, L"%USERPROFILE%\\") < 0 ||
-		root.path[0] == L'%') /* i.e. no expansion happened */
-	{
-		giterr_set(GITERR_OS, "Cannot locate the user's profile directory");
-		return -1;
+	if (home != NULL) {
+		if (git_buf_joinpath(path, home, filename) < 0)
+			return -1;
+
+		if (git_path_exists(path->ptr)) {
+			return 0;
+		}
+	}
+
+	if (getenv("HOMEPATH") != NULL) {
+		if (win32_expand_path(&root, L"%HOMEDRIVE%%HOMEPATH%\\") < 0 ||
+			root.path[0] == L'%') /* i.e. no expansion happened */
+		{
+			giterr_set(GITERR_OS, "Cannot locate the user's profile directory");
+			return -1;
+		}
+	} else {
+		if (win32_expand_path(&root, L"%USERPROFILE%\\") < 0 ||
+			root.path[0] == L'%') /* i.e. no expansion happened */
+		{
+			giterr_set(GITERR_OS, "Cannot locate the user's profile directory");
+			return -1;
+		}
 	}
 
 	if (win32_find_file(path, &root, filename) < 0) {
@@ -473,8 +437,6 @@ int git_futils_find_global_file(git_buf *path, const char *filename)
 
 	return 0;
 #else
-	const char *home = getenv("HOME");
-
 	if (home == NULL) {
 		giterr_set(GITERR_OS, "Global file lookup failed. "
 			"Cannot locate the user's home directory");
diff --git a/src/repository.c b/src/repository.c
index 1b49228..96370c7 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -446,6 +446,7 @@ static int load_config(
 	git_config **out,
 	git_repository *repo,
 	const char *global_config_path,
+	const char *xdg_config_path,
 	const char *system_config_path)
 {
 	git_buf config_path = GIT_BUF_INIT;
@@ -460,13 +461,18 @@ static int load_config(
 		&config_path, repo->path_repository, GIT_CONFIG_FILENAME_INREPO) < 0)
 		goto on_error;
 
-	if (git_config_add_file_ondisk(cfg, config_path.ptr, 3) < 0)
+	if (git_config_add_file_ondisk(cfg, config_path.ptr, 4) < 0)
 		goto on_error;
 
 	git_buf_free(&config_path);
 
 	if (global_config_path != NULL) {
-		if (git_config_add_file_ondisk(cfg, global_config_path, 2) < 0)
+		if (git_config_add_file_ondisk(cfg, global_config_path, 3) < 0)
+			goto on_error;
+	}
+
+	if (xdg_config_path != NULL) {
+		if (git_config_add_file_ondisk(cfg, xdg_config_path, 2) < 0)
 			goto on_error;
 	}
 
@@ -488,19 +494,23 @@ on_error:
 int git_repository_config__weakptr(git_config **out, git_repository *repo)
 {
 	if (repo->_config == NULL) {
-		git_buf global_buf = GIT_BUF_INIT, system_buf = GIT_BUF_INIT;
+		git_buf global_buf = GIT_BUF_INIT, xdg_buf = GIT_BUF_INIT, system_buf = GIT_BUF_INIT;
 		int res;
 
 		const char *global_config_path = NULL;
+		const char *xdg_config_path = NULL;
 		const char *system_config_path = NULL;
 
 		if (git_config_find_global_r(&global_buf) == 0)
 			global_config_path = global_buf.ptr;
 
+		if (git_config_find_xdg_r(&xdg_buf) == 0)
+			xdg_config_path = xdg_buf.ptr;
+
 		if (git_config_find_system_r(&system_buf) == 0)
 			system_config_path = system_buf.ptr;
 
-		res = load_config(&repo->_config, repo, global_config_path, system_config_path);
+		res = load_config(&repo->_config, repo, global_config_path, xdg_config_path, system_config_path);
 
 		git_buf_free(&global_buf);
 		git_buf_free(&system_buf);
diff --git a/src/win32/findfile.c b/src/win32/findfile.c
new file mode 100644
index 0000000..de9373c
--- /dev/null
+++ b/src/win32/findfile.c
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "utf-conv.h"
+#include "path.h"
+#include "findfile.h"
+
+#ifndef _WIN64
+#define REG_MSYSGIT_INSTALL L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Git_is1"
+#else
+#define REG_MSYSGIT_INSTALL L"SOFTWARE\\Wow6432Node\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Git_is1"
+#endif
+
+int win32_expand_path(struct win32_path *s_root, const wchar_t *templ)
+{
+	s_root->len = ExpandEnvironmentStringsW(templ, s_root->path, MAX_PATH);
+	return s_root->len ? 0 : -1;
+}
+
+int win32_find_file(git_buf *path, const struct win32_path *root, const char *filename)
+{
+	size_t len, alloc_len;
+	wchar_t *file_utf16 = NULL;
+	char file_utf8[GIT_PATH_MAX];
+
+	if (!root || !filename || (len = strlen(filename)) == 0)
+		return GIT_ENOTFOUND;
+
+	/* allocate space for wchar_t path to file */
+	alloc_len = root->len + len + 2;
+	file_utf16 = git__calloc(alloc_len, sizeof(wchar_t));
+	GITERR_CHECK_ALLOC(file_utf16);
+
+	/* append root + '\\' + filename as wchar_t */
+	memcpy(file_utf16, root->path, root->len * sizeof(wchar_t));
+
+	if (*filename == '/' || *filename == '\\')
+		filename++;
+
+	git__utf8_to_16(file_utf16 + root->len - 1, alloc_len, filename);
+
+	/* check access */
+	if (_waccess(file_utf16, F_OK) < 0) {
+		git__free(file_utf16);
+		return GIT_ENOTFOUND;
+	}
+
+	git__utf16_to_8(file_utf8, file_utf16);
+	git_path_mkposix(file_utf8);
+	git_buf_sets(path, file_utf8);
+
+	git__free(file_utf16);
+	return 0;
+}
+
+wchar_t* win32_nextpath(wchar_t *path, wchar_t *buf, size_t buflen)
+{
+	wchar_t term, *base = path;
+
+	assert(path && buf && buflen);
+
+	term = (*path == L'"') ? *path++ : L';';
+
+	for (buflen--; *path && *path != term && buflen; buflen--)
+		*buf++ = *path++;
+
+	*buf = L'\0'; /* reserved a byte via initial subtract */
+
+	while (*path == term || *path == L';')
+		path++;
+
+	return (path != base) ? path : NULL;
+}
+
+int win32_find_system_file_using_path(git_buf *path, const char *filename)
+{
+	wchar_t * env = NULL;
+	struct win32_path root;
+
+	env = _wgetenv(L"PATH");
+	if (!env)
+		return -1;
+
+	// search in all paths defined in PATH
+	while ((env = win32_nextpath(env, root.path, MAX_PATH - 1)) != NULL && *root.path)
+	{
+		wchar_t * pfin = root.path + wcslen(root.path) - 1; // last char of the current path entry
+
+		// ensure trailing slash
+		if (*pfin != L'/' && *pfin != L'\\')
+			wcscpy(++pfin, L"\\"); // we have enough space left, MAX_PATH - 1 is used in nextpath above
+
+		root.len = (DWORD)wcslen(root.path) + 1;
+
+		if (win32_find_file(path, &root, "git.cmd") == 0 || win32_find_file(path, &root, "git.exe") == 0) {
+			// we found the cmd or bin directory of a git installaton
+			if (root.len > 5) {
+				wcscpy(root.path + wcslen(root.path) - 4, L"etc\\");
+				if (win32_find_file(path, &root, filename) == 0)
+					return 0;
+			}
+		}
+	}
+	
+	return GIT_ENOTFOUND;
+}
+
+int win32_find_system_file_using_registry(git_buf *path, const char *filename)
+{
+	struct win32_path root;
+
+	HKEY hKey;
+	DWORD dwType = REG_SZ;
+	DWORD dwSize = MAX_PATH;
+
+	root.len = 0;
+	if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, REG_MSYSGIT_INSTALL, 0, KEY_ALL_ACCESS, &hKey) == ERROR_SUCCESS)
+	{
+		if (RegQueryValueExW(hKey, L"InstallLocation", NULL, &dwType,(LPBYTE)&root.path, &dwSize) == ERROR_SUCCESS)
+		{
+			// InstallLocation points to the root of the msysgit directory
+			if (dwSize + 4 > MAX_PATH) // 4 = wcslen(L"etc\\")
+			{
+				giterr_set(GITERR_OS, "Cannot locate the system's msysgit directory - path too long");
+				return -1;
+			}
+			wcscat(root.path, L"etc\\");
+			root.len = (DWORD)wcslen(root.path) + 1;
+		}
+	}
+	RegCloseKey(hKey);
+
+	if (!root.len) {
+		giterr_set(GITERR_OS, "Cannot locate the system's msysgit directory");
+		return -1;
+	}
+
+	if (win32_find_file(path, &root, filename) < 0) {
+		giterr_set(GITERR_OS, "The system file '%s' doesn't exist", filename);
+		git_buf_clear(path);
+		return GIT_ENOTFOUND;
+	}
+
+	return 0;
+}
diff --git a/src/win32/findfile.h b/src/win32/findfile.h
new file mode 100644
index 0000000..8751b73
--- /dev/null
+++ b/src/win32/findfile.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef INCLUDE_git_findfile_h__
+#define INCLUDE_git_findfile_h__
+
+struct win32_path {
+	wchar_t path[MAX_PATH];
+	DWORD len;
+};
+
+int win32_expand_path(struct win32_path *s_root, const wchar_t *templ);
+
+int win32_find_file(git_buf *path, const struct win32_path *root, const char *filename);
+int win32_find_system_file_using_path(git_buf *path, const char *filename);
+int win32_find_system_file_using_registry(git_buf *path, const char *filename);
+
+#endif
+