Skip to content

readv

Intro

readv - read data from a file descriptor into multiple buffers

Description

The readv() system call reads data from a file descriptor into multiple buffers, specified with the array iov. Each element in the array contains the location and number of bytes to read. Up to iovcnt elements can be read from an array.

The readv() call operates similarly to a call of read() except for the arrays of vectors, rather than a single user buffer. The readv() call is then useful for reading from a file or socket into multiple buffers, allowing for greater efficiency when working with large datasets.

Edge cases: Depending on the value used for the iovcnt argument, fewer than the requested number of bytes may be written to the output buffers.

Arguments

  • fd:int - the file descriptor from which the data should be read.
  • iov:const struct iovec*[KU] - an array containing the location and number of bytes to read.
  • iovcnt:int - the number of elements in the iov array that should be used.

Available Tags

  • K - Originated from kernel-space.
  • U - Originated from user space (for example, pointer to user space memory used to get it)

Hooks

readv

Type

Kprobe + Kretprobe

Purpose

To be able to trace when the system call readv gets triggered, in order to determine when data is being read from a file descriptor into multiple buffers.

Example Use Case

readv() can be used to read a large amount of data from a file descriptor into multiple buffers, for example for writing to a log file or sending large datasets over a network.

Issues

No issues known for this event.

  • writev
  • preadv
  • preadv2
  • pwritev
  • pwritev2

This document was automatically generated by OpenAI and needs review. It might not be accurate and might contain errors. The authors of Tracee recommend that the user reads the "events.go" source file to understand the events and their arguments better.