lua-io-read

Reads data from a specified file descriptor.

Installation

luarocks install io-read

---

Error Handling

the following functions return the error object created by https://github.com/mah0x211/lua-errno module.

data, err, again = read( file [, count [, offset]] )

Reads data from the specified file handle or file descriptor.

Parameters

• file:file*|integer: a file handle or a file descriptor.
• count:integer: the number of bytes to read. if the count is not specified, then it will be read until the end of the file. (default: nil)
• offset:integer: the offset in bytes from the beginning of the file to start reading. if the offset is specified, then the file position will be moved to the specified offset before reading. (default: nil)

Returns

• data:string: read data.
• err:any: error object.
• again:boolean: true if the read operation is incomplete (read syscall returned EAGAIN, EWOULDBLOCK, or EINTR) and the data is not available.

Usage

local read = require('io.read')
local f = assert(io.open('./test.txt'))

-- read 10 bytes from the file
local data, err, again = read(f, 10)
if data then
    print(data)
elseif again then
    print('read syscall returned EAGAIN or EWOULDBLOCK')
elseif err then
    print('read syscall is failed:', err)
else
    print('end of file')
end