# PR_TransmitFile

Sends a complete file across a connected socket.

## Syntax

```{code}
#include <prio.h>

PRInt32 PR_TransmitFile(
  PRFileDesc *networkSocket,
  PRFileDesc *sourceFile,
  const void *headers,
  PRInt32 hlen,
  PRTransmitFileFlags flags,
  PRIntervalTime timeout);
```

### Parameters

The function has the following parameters:

`networkSocket`

: A pointer to a {ref}`PRFileDesc` object representing the connected
  socket to send data over.

`sourceFile`

: A pointer to a {ref}`PRFileDesc` object representing the file to send.

`headers`

: A pointer to the buffer holding the headers to be sent before sending
  data.

`hlen`

: Length of the `headers` buffer in bytes.

`flags`
: > One of the following flags:

- `PR_TRANSMITFILE_KEEP_OPEN` indicates that the socket will be kept
  open after the data is sent.
- `PR_TRANSMITFILE_CLOSE_SOCKET` indicates that the connection should
  be closed immediately after successful transfer of the file.

`timeout`

: Time limit for completion of the transmit operation.

### Returns

- A positive number indicates the number of bytes successfully written,
  including both the headers and the file.
- The value -1 indicates a failure. If an error occurs while sending
  the file, the `PR_TRANSMITFILE_CLOSE_SOCKET` flag is ignored. The
  reason for the failure can be obtained by calling {ref}`PR_GetError`.

## Description

The {ref}`PR_TransmitFile` function sends a complete file (`sourceFile`)
across a connected socket (`networkSocket`). If `headers` is
non-`NULL`, {ref}`PR_TransmitFile` sends the headers across the socket
before sending the file.

The enumeration `PRTransmitFileFlags`, used in the `flags`
parameter, is defined as follows:

```{code}
typedef enum PRTransmitFileFlags {
  PR_TRANSMITFILE_KEEP_OPEN = 0,
  PR_TRANSMITFILE_CLOSE_SOCKET = 1
} PRTransmitFileFlags;
```