On Tue, 2004-07-20 17:41:42 +0200, Gerald Emig [off-list ref]
wrote in message [ref]:

According to the documentation provided in info:libc, read 
returns the number of character it actually has read.
Especially if you are using serial ports, the amount read is often fewer
as you expected.

That's a general thing to keep in mind.

Additionally, keep in mind that c_cc[VMIN] will control how long to
wait, too...

Additionally, checking errno is stronly recommended.

As always:)

Use something like the following to read exactly 200 chars:


int read_amount (int iwantread)

This int should have been size_t.

{
	int readpointer, fetch;

...and fetch needs to be ssize_t.

readpointer=0;
while (iwantread>0) {
	fetch=read (fd,&buffer[readpointer],iwantread);
	if (fetch >= 0) {
		readpointer += fetch;
		iwantread -= fetch;
	} else 	if ((errno!=EINTR) && (errno!=EAGAIN)) return -1;
	}
	return iwantread; // should be 0 on success
}

MfG, JBG

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