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clinuxsocketstcp
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Reputation: 846

When data is sent over a Socket, when does send/write returns -1?

Linux. Tcp socket.

When does a send()/write() command fail?

Does it return -1 only if the TCP send buffer in the kernel overflow?

Upvotes: 2

Views: 731

Answers (2)

Brad
Brad

Reputation: 11515

To your specific point - if your write call was blocking, (as is the default), an overflow would just block you until there was buffer space available.

If the write call was non-blocking, and the buffers were full, you would receive an error.

Upvotes: 0

Gavin H
Gavin H

Reputation: 10502

From the OpenGroup definition for write():

Upon successful completion, write() [XSI] and pwrite() shall return the number of bytes actually written to the file associated with fildes. This number shall never be greater than nbyte. Otherwise, -1 shall be returned and errno set to indicate the error.

The same thing is done for send() - OpenGroup page for send()

You will find out more information by looking at the errno. See the OpenGroup page on errno for some more information.

Upvotes: 5

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