modem_read()

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Прототип:

#include <sys/modem.h>
                                       
int modem_read( int fd,
                char *buf,
                int bufsize,
                int quiet,
                int timeout,
                int flags,
                int (*cancel)( void ) );

Аргументы:

fd

The file descriptor for the device that you want to read from; see modem_open().

buf

A pointer to a buffer where the function can store the data.

bufsize

The size of the buffer, in bytes.

quiet

The maximum time to wait for more input after receiving at least one characters, in tenths of a second.

timeout

The maximum time to wait for any input, in tenths of a second.

flags

Flags that you can use to filter and map received characters; any combination of:

MODEM_ALLOWCASE

preserve the case of incoming characters. Without this flag, all letters are mapped to lower case.

MODEM_ALLOWCTRL

allow control characters. Without this flag, control characters are discarded.

MODEM_ALLOW8BIT

preserve the top bit of incoming characters. Without this flag, the top bit is set to zero for all characters.

MODEM_LASTLINE

discard all previously received characters when a newline is received followed by more characters. Without this flag, buf may contain multiple lines. If an automatic login script may be presented with an arbitrary text screen before the login prompt, you can use this flag to discard all but the login line, reducing the possibility of false matches.

cancel

NULL, or a callback that's called whenever the quiet time period expires while waiting for more input.

Библиотека:

libc

Описание:

The modem_read() function reads up to bufsize bytes from the device specified by the file descriptor, fd, and places them into the buffer pointed to by buf.

If no characters are received within the given timeout, modem_read() returns with -1.

When at least one character has been received, modem_read() returns if the flow of incoming characters stops for at least the quiet time period. The number of characters saved in buf is returned.

If you provide a cancel function, it's called once each quiet time period while waiting for input. If this function returns a nonzero value, modem_read() returns -1 immediately and sets errno to ETIMEDOUT. You can use the cancel function as a callback in a graphical dialer that needs to support a cancel button to stop a script (see modem_script()).

Возвращаемое значение:

0

Успешное завершение.

-1

Возникла ошибка. Код ошибки записан в errno.

Коды ошибок:

EAGAIN

The O_NONBLOCK flag is set on this fd, and the process would have been blocked in trying to perform this operation.

EBADF

The argument fd is invalid, or the file isn't opened for reading.

EINTR

The readcond() call was interrupted by the process being signalled.

EIO

This process isn't currently able to read data from this fd.

ENOSYS

This function isn't supported for this fd.

Классификация:

ЗОСРВ «Нейтрино»

Точка остановки потока

Да

Обработчик прерываний

Нет

Обработчик сигналов

Смотри ниже

В потоке

Смотри ниже

Предостережения:

Depending on what you do in your cancel function, modem_read() may or not be signal handler or thread-safe.

Тематические ссылки:

modem_open(), modem_script(), modem_write()

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