getpwuid(mingw): provide a better default for the user name

We do have the excellent GetUserInfoEx() function to obtain more detailed information of the current user (if the user is part of a Windows domain); Let's use it. Suggested by Lutz Roeder. To avoid the cost of loading Secur32.dll (even lazily, loading DLLs takes a non-neglibile amount of time), we use the established technique to load DLLs only when, and if, needed. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Johannes Schindelin committed Oct 15, 2018 at 02:47 UTC 564be791f33a72d28497420dafbd3b272b9a1380
1 file changed +31 -1
compat/mingw.c
+31 -1
@@ -5,6 +5,7 @@
5 #include "../strbuf.h"
6 #include "../run-command.h"
7 #include "../cache.h"
8 +#include "win32/lazyload.h"
9
10 #define HCAST(type, handle) ((type)(intptr_t)handle)
11
@@ -1768,6 +1769,33 @@ int mingw_getpagesize(void)
1769 return si.dwAllocationGranularity;
1770 }
1771
1772 +/* See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724435.aspx */
1773 +enum EXTENDED_NAME_FORMAT {
1774 + NameDisplay = 3,
1775 + NameUserPrincipal = 8
1776 +};
1777 +
1778 +static char *get_extended_user_info(enum EXTENDED_NAME_FORMAT type)
1779 +{
1780 + DECLARE_PROC_ADDR(secur32.dll, BOOL, GetUserNameExW,
1781 + enum EXTENDED_NAME_FORMAT, LPCWSTR, PULONG);
1782 + static wchar_t wbuffer[1024];
1783 + DWORD len;
1784 +
1785 + if (!INIT_PROC_ADDR(GetUserNameExW))
1786 + return NULL;
1787 +
1788 + len = ARRAY_SIZE(wbuffer);
1789 + if (GetUserNameExW(type, wbuffer, &len)) {
1790 + char *converted = xmalloc((len *= 3));
1791 + if (xwcstoutf(converted, wbuffer, len) >= 0)
1792 + return converted;
1793 + free(converted);
1794 + }
1795 +
1796 + return NULL;
1797 +}
1798 +
1799 struct passwd *getpwuid(int uid)
1800 {
1801 static unsigned initialized;
@@ -1786,7 +1814,9 @@ struct passwd *getpwuid(int uid)
1814
1815 p = xmalloc(sizeof(*p));
1816 p->pw_name = user_name;
1789 - p->pw_gecos = "unknown";
1817 + p->pw_gecos = get_extended_user_info(NameDisplay);
1818 + if (!p->pw_gecos)
1819 + p->pw_gecos = "unknown";
1820 p->pw_dir = NULL;
1821
1822 initialized = 1;