Make improvements

- Introduce ualarm() function
- Make rename() report EISEMPTY on Windows
- Always raise EINVAL upon open(O_RDONLY|O_TRUNC)
- Add macro so ./configure will detect SOCK_CLOEXEC
- Fix O_TRUNC without O_CREAT not working on Windows
- Let fcntl(F_SETFL) change O_APPEND status on Windows
- Make sure pwrite() / pread() report ESPIPE on sockets
- Raise ESPIPE on Windows when pwrite() is used on pipe
- Properly compute O_APPEND CreateFile() flags on Windows
- Don't require O_DIRECTORY to open directories on Windows
- Fix more instances of Windows reporting EISDIR and ENOTDIR
- Normalize EFTYPE and EMLINK to ELOOP on NetBSD and FreeBSD
- Make unlink() / rmdir() work on read-only files on Windows
- Validate UTF-8 on Windows paths to fix bug with overlong NUL
- Always print signal name to stderr when crashing due to SIG_DFL
- Fix Windows bug where denormalized paths >260 chars didn't work
- Block signals on BSDs when thread exits before trashing its own stack

test/libc/calls/readlinkat_test.c

@@ -62,9 +62,6 @@ TEST(readlinkat, test) {
   EXPECT_EQ(255, buf[8] & 255);
   buf[8] = 0;
   EXPECT_STREQ("hello→", buf);
-  p = gc(xjoinpaths(g_testlib_tmpdir, "hello→"));
-  q = gc(realpath("there→", 0));
-  EXPECT_EQ(0, strcmp(p, q), "%`'s\n\t%`'s", p, q);
 }
 
 TEST(readlinkat, efault) {
@@ -89,10 +86,7 @@ TEST(readlinkat, frootloop) {
   ASSERT_SYS(0, 0, symlink("froot", "froot"));
   ASSERT_SYS(ELOOP, -1, readlink("froot/loop", buf, sizeof(buf)));
   if (O_NOFOLLOW) {
-    ASSERT_SYS(IsFreebsd()  ? EMLINK
-               : IsNetbsd() ? EFTYPE
-                            : ELOOP,
-               -1, open("froot", O_RDONLY | O_NOFOLLOW));
+    ASSERT_SYS(ELOOP, -1, open("froot", O_RDONLY | O_NOFOLLOW));
     if (0 && O_PATH) { /* need rhel5 test */
       ASSERT_NE(-1, (fd = open("froot", O_RDONLY | O_NOFOLLOW | O_PATH)));
       ASSERT_NE(-1, close(fd));