# PR_Read

Reads bytes from a file or socket.

## Syntax

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

PRInt32 PR_Read(PRFileDesc *fd,
               void *buf,
               PRInt32 amount);
```

### Parameters

The function has the following parameters:

`fd`

: A pointer to a {ref}`PRFileDesc` object for the file or socket.

`buf`

: A pointer to a buffer to hold the data read in. On output, the buffer
  contains the data.

`amount`

: The size of `buf` (in bytes).

### Returns

One of the following values:

- A positive number indicates the number of bytes actually read in.
- The value 0 means end of file is reached or the network connection is
  closed.
- The value -1 indicates a failure. To get the reason for the failure,
  call {ref}`PR_GetError`.

## Description

The thread invoking {ref}`PR_Read` blocks until it encounters an
end-of-stream indication, some positive number of bytes (but no more
than `amount` bytes) are read in, or an error occurs.