Make vim startup faster

It appears that GetFileAttributes(u"\\etc\\passwd") can take two seconds
on Windows 10 at unpredictable times for reasons which are mysterious to
me. Let's try avoiding that path entirely and pray to Microsoft it works

libc/calls/fixenotdir.c

@@ -23,10 +23,20 @@
 #include "libc/nt/files.h"
 #include "libc/str/str.h"
 
+static int IsAlpha(int c) {
+  return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
+}
+
 static textwindows bool SubpathExistsThatsNotDirectory(char16_t *path) {
   char16_t *p;
   uint32_t attrs;
   while ((p = strrchr16(path, '\\'))) {
+    if (p == path)
+      // don't bother checking GetFileAttributes(u"\\")
+      break;
+    if (p == path + 2 && IsAlpha(path[0]) && path[1] == ':')
+      // don't bother checking GetFileAttributes(u"C:\\")
+      break;
     *p = u'\0';
     if ((attrs = GetFileAttributes(path)) != -1u &&
         !(attrs & kNtFileAttributeDirectory)) {

libc/calls/mkntpathat.c

@@ -75,6 +75,7 @@ static textwindows int __mkntpathath_impl(int64_t dirhand, const char *path,
 
     return n;
   } else {
+    filelen = __normntpath(file, filelen);
     return filelen;
   }
 }
@@ -84,23 +85,20 @@ textwindows int __mkntpathath(int64_t dirhand, const char *path, int flags,
 
   // convert the path.
   int len;
-  if ((len = __mkntpathath_impl(dirhand, path, flags, file)) == -1) {
+  if ((len = __mkntpathath_impl(dirhand, path, flags, file)) == -1)
     return -1;
-  }
 
   // if path ends with a slash, then we need to manually do what linux
   // does and check to make sure it's a directory, and return ENOTDIR,
   // since WIN32 will reject the path with EINVAL if we don't do this.
   if (len && file[len - 1] == '\\') {
     uint32_t fattr;
-    if (len > 1 && !(len == 3 && file[1] == ':')) {
+    if (len > 1 && !(len == 3 && file[1] == ':'))
       file[--len] = 0;
-    }
     if ((fattr = GetFileAttributes(file)) != -1u &&
         !(fattr & kNtFileAttributeReparsePoint) &&
-        !(fattr & kNtFileAttributeDirectory)) {
+        !(fattr & kNtFileAttributeDirectory))
       return enotdir();
-    }
   }
 
   return len;

libc/dlopen/dlopen.c

@@ -631,11 +631,11 @@ static dontinline bool foreign_compile(char exe[hasatleast PATH_MAX]) {
     errno = err;
     return false;
   }
-  while (waitpid(pid, &ws, 0) == -1) {
-    if (errno != EINTR) {
-      unlink(tmp);
-      return false;
-    }
+  if (waitpid(pid, &ws, 0) == -1) {
+    // signals and cancelation are blocked
+    // therefore this must be a real error
+    unlink(tmp);
+    return false;
   }
   if (ws) {
     unlink(tmp);

libc/intrin/getfileattributes.c

@@ -19,6 +19,7 @@
 #include "libc/intrin/describeflags.h"
 #include "libc/intrin/strace.h"
 #include "libc/nt/files.h"
+#include "libc/nt/runtime.h"
 #include "libc/nt/thunk/msabi.h"
 
 __msabi extern typeof(GetFileAttributes) *const __imp_GetFileAttributesW;
@@ -30,7 +31,7 @@ __msabi extern typeof(GetFileAttributes) *const __imp_GetFileAttributesW;
 textwindows uint32_t GetFileAttributes(const char16_t *lpPathName) {
   uint32_t flags;
   flags = __imp_GetFileAttributesW(lpPathName);
-  NTTRACE("GetFileAttributes(%#hs) → %s", lpPathName,
-          DescribeNtFileFlagAttr(flags));
+  NTTRACE("GetFileAttributes(%#hs) → {%s, %d}", lpPathName,
+          DescribeNtFileFlagAttr(flags), GetLastError());
   return flags;
 }

third_party/musl/pwd.c

@@ -91,8 +91,9 @@ __fopen_passwd(void)
 {
 	FILE *f;
 	char *s;
-	// MacOS has a fake /etc/passwd file without any user details.
-	if (!IsXnu() && (f = fopen("/etc/passwd", "rbe")))
+	// MacOS has a fake /etc/passwd file without any user details
+	// GetFileAttributes(u"\\etc\\passwd") takes 2 seconds sometimes
+	if (!IsXnu() && !IsWindows() && (f = fopen("/etc/passwd", "rbe")))
 		return f;
 	if (!(s = __create_synthetic_passwd_file()))
 		return 0;