PR ImportTCPSocket

Imports a native TCP socket into NSPR.


#include "private/pprio.h"

PRFileDesc* PR_ImportTCPSocket(PROsfd osfd);


The function has the following parameters:

The native file descriptor for the TCP socket to import. On POSIX systems, this is an int. On Windows, this is a SOCKET.


The function returns one of the following values:

  • Upon successful completion, a pointer to the PRFileDesc object created for the newly imported native TCP socket.
  • If the import of the native TCP socket failed, NULL.


A native TCP socket osfd can be imported into NSPR with PR_ImportTCPSocket. The caller gives up control of the native TCP socket osfd and should use the PRFileDesc* returned by PR_ImportTCPSocket instead.

Although PR_ImportTCPSocket is a supported function, it is declared in "private/pprio.h" to stress the fact that this function depends on the internals of the NSPR implementation. The caller needs to understand what NSPR will do to the native file descriptor and make sure that NSPR can use the native file descriptor successfully.

For example, on POSIX systems, NSPR will put the native file descriptor (an int) in non-blocking mode by calling fcntl to set the O_NONBLOCK file status flag on the native file descriptor, and then NSPR will call socket functions such as recv, send, and poll on the native file descriptor. The caller must not do anything to the native file descriptor before the PR_ImportTCPSocket call that will prevent the native file descriptor from working in non-blocking mode.


In theory, code that uses PR_ImportTCPSocket may break when NSPR's implementation changes. In practice, this is unlikely to happen because NSPR's implementation has been stable for years and because of NSPR's strong commitment to backward compatibility. Using PR_ImportTCPSocket is much more convenient than writing an NSPR I/O layer that wraps your native TCP sockets. Of course, it is best if you just use PR_OpenTCPSocket or PR_NewTCPSocket. If you are not sure whether PR_ImportTCPSocket is right for you, please ask in the newsgroup.

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 Contributors to this page: teoli, Wtchang
 Last updated by: teoli,