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

libc/calls/pread.c

@@ -29,8 +29,8 @@
 #include "libc/intrin/weaken.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/runtime.h"
-#include "libc/sysv/errfuns.h"
 #include "libc/runtime/zipos.internal.h"
+#include "libc/sysv/errfuns.h"
 
 /**
  * Reads from file at offset.
@@ -71,6 +71,8 @@ ssize_t pread(int fd, void *buf, size_t size, int64_t offset) {
         (struct iovec[]){{buf, size}}, 1, offset);
   } else if (!IsWindows()) {
     rc = sys_pread(fd, buf, size, offset, offset);
+  } else if (__isfdkind(fd, kFdSocket)) {
+    rc = espipe();
   } else if (__isfdkind(fd, kFdFile)) {
     rc = sys_read_nt(&g_fds.p[fd], (struct iovec[]){{buf, size}}, 1, offset);
   } else {