Improve the default user name & email logic

compat/mingw.c

@@ -1915,18 +1915,63 @@ int mingw_getpagesize(void)
 	return si.dwAllocationGranularity;
 }
 
+/* See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724435.aspx */
+enum EXTENDED_NAME_FORMAT {
+	NameDisplay = 3,
+	NameUserPrincipal = 8
+};
+
+static char *get_extended_user_info(enum EXTENDED_NAME_FORMAT type)
+{
+	DECLARE_PROC_ADDR(secur32.dll, BOOL, GetUserNameExW,
+		enum EXTENDED_NAME_FORMAT, LPCWSTR, PULONG);
+	static wchar_t wbuffer[1024];
+	DWORD len;
+
+	if (!INIT_PROC_ADDR(GetUserNameExW))
+		return NULL;
+
+	len = ARRAY_SIZE(wbuffer);
+	if (GetUserNameExW(type, wbuffer, &len)) {
+		char *converted = xmalloc((len *= 3));
+		if (xwcstoutf(converted, wbuffer, len) >= 0)
+			return converted;
+		free(converted);
+	}
+
+	return NULL;
+}
+
+char *mingw_query_user_email(void)
+{
+	return get_extended_user_info(NameUserPrincipal);
+}
+
 struct passwd *getpwuid(int uid)
 {
+	static unsigned initialized;
 	static char user_name[100];
-	static struct passwd p;
+	static struct passwd *p;
+	DWORD len;
+
+	if (initialized)
+		return p;
 
-	DWORD len = sizeof(user_name);
-	if (!GetUserName(user_name, &len))
+	len = sizeof(user_name);
+	if (!GetUserName(user_name, &len)) {
+		initialized = 1;
 		return NULL;
-	p.pw_name = user_name;
-	p.pw_gecos = "unknown";
-	p.pw_dir = NULL;
-	return &p;
+	}
+
+	p = xmalloc(sizeof(*p));
+	p->pw_name = user_name;
+	p->pw_gecos = get_extended_user_info(NameDisplay);
+	if (!p->pw_gecos)
+		p->pw_gecos = "unknown";
+	p->pw_dir = NULL;
+
+	initialized = 1;
+	return p;
 }
 
 static HANDLE timer_event;

compat/mingw.h

@@ -430,6 +430,8 @@ int mingw_offset_1st_component(const char *path);
 #define PATH_SEP ';'
 extern const char *program_data_config(void);
 #define git_program_data_config program_data_config
+extern char *mingw_query_user_email(void);
+#define query_user_email mingw_query_user_email
 #ifndef __MINGW64_VERSION_MAJOR
 #define PRIuMAX "I64u"
 #define PRId64 "I64d"

git-compat-util.h

@@ -373,6 +373,10 @@ static inline char *git_find_last_dir_sep(const char *path)
 #define git_program_data_config() NULL
 #endif
 
+#ifndef query_user_email
+#define query_user_email() NULL
+#endif
+
 #if defined(__HP_cc) && (__HP_cc >= 61000)
 #define NORETURN __attribute__((noreturn))
 #define NORETURN_PTR

ident.c

@@ -120,7 +120,9 @@ const char *ident_default_email(void)
 			strbuf_addstr(&git_default_email, email);
 			committer_ident_explicitly_given |= IDENT_MAIL_GIVEN;
 			author_ident_explicitly_given |= IDENT_MAIL_GIVEN;
-		} else
+		} else if ((email = query_user_email()) && email[0])
+			strbuf_addstr(&git_default_email, email);
+		else
 			copy_email(xgetpwuid_self(), &git_default_email);
 		strbuf_trim(&git_default_email);
 	}