writev¶

Intro¶

writev - atomically write data from multiple buffers to a file descriptor

Description¶

The writev() system call writes data from multiple buffers, as specified by iov into a file descriptor fd. The number of buffers to write is given in iovcnt. The iov is a pointer to a list of struct iovecs, which define multiple non-contiguous buffers. Each struct iovec contains a starting address and length of a data buffer. writev() atomicly writes all of the data in the given buffers. If all the buffers are written then the writev() system call returns the total number of bytes written to the file descriptor fd.

Arguments¶

fd:int[K] - A file descriptor that identifies the file into which writev() will write data.
iov:const struct iovec*[K,U] - A pointer to the struct iovec that defines the multiple non-contiguous buffers.
iovcnt:int[OPT,K] - The number of buffers to write, as specified by iov.

Available Tags¶

K - Originated from kernel-space.
U - Originated from user space (for example, pointer to user space memory used to get it)
OPT - Optional argument - might not always be available (passed with null value)

Hooks¶

sys_writev¶

Type¶

kprobes

Purpose¶

Hooked to trace the sys_writev syscall.

Example Use Case¶

writev() is often used when writing to a socket. For example, when sending data to a web server the data is usually split into multiple chunks and writev() is used to write the data in a single operation, atomically.

Issues¶

There are no known issues with the writev() system call.

readv

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.