Provide a default progname on Windows

[guillem@hadrons.org:
 - Remove .exe extension from default program name.
 - Call reallocarray() once by switching to a «do {} while» loop.
 - Minor coding style fixes. ]

Signed-off-by: Guillem Jover <guillem@hadrons.org>

diff --git a/src/progname.c b/src/progname.c
index 3edbf24b31787f22c66024e97663769cb8ebf8bd..bebf7141705c3ee3997c392c6e2879f15b8c2003 100644 (file)
--- a/src/progname.c
+++ b/src/progname.c
@@ -1,6 +1,7 @@
 /*
  * Copyright © 2006 Robert Millan
  * Copyright © 2010-2012 Guillem Jover <guillem@hadrons.org>
+ * Copyright © 2018 Facebook, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -30,11 +31,16 @@
  * <https://sourceware.org/ml/libc-alpha/2006-03/msg00125.html>.
  */
 
+#include <sys/param.h>
 #include <errno.h>
 #include <string.h>
 #include <stdlib.h>
+#ifdef _WIN32
+#include <Windows.h>
+#include <shlwapi.h>
+#endif
 
-#if defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)
+#ifdef _WIN32
 #define LIBBSD_IS_PATHNAME_SEPARATOR(c) ((c) == '/' || (c) == '\\')
 #else
 #define LIBBSD_IS_PATHNAME_SEPARATOR(c) ((c) == '/')
@@ -56,6 +62,70 @@ getprogname(void)
        /* getexecname(3) returns an absolute pathname, normalize it. */
        if (__progname == NULL)
                setprogname(getexecname());
+#elif defined(_WIN32)
+       if (__progname == NULL) {
+               WCHAR *wpath = NULL;
+               WCHAR *wname = NULL;
+               WCHAR *wext = NULL;
+               DWORD wpathsiz = MAX_PATH / 2;
+               DWORD len, i;
+               char *mbname = NULL;
+               int mbnamesiz;
+
+               /* Use the Unicode version of this function to support long
+                * paths. MAX_PATH isn't actually the maximum length of a
+                * path in this case. */
+               do {
+                       WCHAR *wpathnew;
+
+                       wpathsiz *= 2;
+                       wpathsiz = MIN(wpathsiz, UNICODE_STRING_MAX_CHARS);
+                       wpathnew = reallocarray(wpath, wpathsiz, sizeof(*wpath));
+                       if (wpathnew == NULL)
+                               goto done;
+                       wpath = wpathnew;
+
+                       len = GetModuleFileNameW(NULL, wpath, wpathsiz);
+                       if (wpathsiz == UNICODE_STRING_MAX_CHARS)
+                               goto done;
+               } while (wpathsiz == len);
+               if (len == 0)
+                       goto done;
+
+               /* GetModuleFileNameW() retrieves an absolute path. Locate the
+                * filename now to only convert necessary characters and save
+                * memory. */
+               wname = wpath;
+               for (i = len; i > 0; i--) {
+                       if (LIBBSD_IS_PATHNAME_SEPARATOR(wpath[i - 1])) {
+                               wname = wpath + i;
+                               break;
+                       }
+               }
+
+               /* Remove any trailing extension, such as '.exe', to make the
+                * behavior mach the non-Windows systems. */
+               wext = PathFindExtensionW(wname);
+               wext[0] = '\0';
+
+               mbnamesiz = WideCharToMultiByte(CP_UTF8, 0, wname, -1, NULL,
+                                               0, NULL, NULL);
+               if (mbnamesiz == 0)
+                       goto done;
+               mbname = malloc(mbnamesiz);
+               if (mbname == NULL)
+                       goto done;
+               mbnamesiz = WideCharToMultiByte(CP_UTF8, 0, wname, -1, mbname,
+                                               mbnamesiz, NULL, NULL);
+               if (mbnamesiz == 0)
+                       goto done;
+               __progname = mbname;
+               mbname = NULL;
+
+done:
+               free(wpath);
+               free(mbname);
+       }
 #endif
 
        return __progname;