switch to using high bit for fd detection of file/socket

2 files changed, 33 insertions, 22 deletions

diff --git a/crypto/compat/posix_win.c b/crypto/compat/posix_win.c
index 9409af5..ea229c9 100644
--- a/crypto/compat/posix_win.c
+++ b/crypto/compat/posix_win.c
@@ -22,6 +22,20 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <sys/stat.h>
+
+static int
+is_socket(int fd)
+{
+        return (fd & 0x80000000) == 0;
+}
+
+static int
+get_real_fd(int fd)
+{
+        return (fd & 0x7fffffff);
+}
+
 void
 posix_perror(const char *s)
 {
@@ -43,14 +57,10 @@ posix_fopen(const char *path, const char *mode)
         return fopen(path, mode);
 }
 
-static int
-oddify_fd(int fd)
+int
+posix_fstat(int fd, struct stat *statbuf)
 {
-        if (fd & 1) /* also catches an eventual -1 from using up all descriptors */
-                return fd;
-        int clone = oddify_fd(dup(fd));
-        close(fd);
-        return clone;
+        return fstat(get_real_fd(fd), statbuf);
 }
 
 int
@@ -72,7 +82,11 @@ posix_open(const char *path, ...)
                 flags |= O_NOINHERIT;
         }
         flags &= ~O_NONBLOCK;
-        return oddify_fd(open(path, flags, mode));
+
+        const int fh = open(path, flags, mode);
+
+        // Set high bit to mark file descriptor as a file handle
+        return fh + 0x80000000;
 }
 
 char *
@@ -160,15 +174,6 @@ wsa_errno(int err)
         return -1;
 }
 
-static int
-is_socket(int fd)
-{
-        /* Border case: Don't break std* file descriptors */
-        if (fd < 3)
-                return 0;
-        return (fd & 1) == 0; /* daringly assumes that any valid socket is even */
-}
-
 int
 posix_connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
 {
@@ -182,14 +187,13 @@ int
 posix_close(int fd)
 {
         int rc;
-
         if (is_socket(fd)) {
                 if ((rc = closesocket(fd)) == SOCKET_ERROR) {
                         int err = WSAGetLastError();
                         rc = wsa_errno(err);
                 }
         } else {
-                rc = close(fd);
+                rc = close(get_real_fd(fd));
         }
         return rc;
 }
@@ -198,14 +202,13 @@ ssize_t
 posix_read(int fd, void *buf, size_t count)
 {
         ssize_t rc;
-
         if (is_socket(fd)) {
                 if ((rc = recv(fd, buf, count, 0)) == SOCKET_ERROR) {
                         int err = WSAGetLastError();
                         rc = wsa_errno(err);
                 }
         } else {
-                rc = read(fd, buf, count);
+                rc = read(get_real_fd(fd), buf, count);
         }
         return rc;
 }
@@ -219,7 +222,7 @@ posix_write(int fd, const void *buf, size_t count)
                         rc = wsa_errno(WSAGetLastError());
                 }
         } else {
-                rc = write(fd, buf, count);
+                rc = write(get_real_fd(fd), buf, count);
         }
         return rc;
 }
diff --git a/include/compat/sys/stat.h b/include/compat/sys/stat.h
index b88da1d..aa15c9a 100644
--- a/include/compat/sys/stat.h
+++ b/include/compat/sys/stat.h
@@ -118,4 +118,12 @@
 
 #endif
 
+#ifdef _WIN32
+int posix_fstat(int fd, struct stat *statbuf);
+
+#ifndef NO_REDEF_POSIX_FUNCTIONS
+#define fstat(fd, statbuf) posix_fstat(fd, statbuf)
+#endif
+#endif
+
 #endif