readv(2)                            CLIX                            readv(2)



  NAME

    readv - Reads input into scattered locations

  LIBRARY

    Berkeley Software Distribution Library (libbsd.a)

  SYNOPSIS

    #include <sys/types.h>

    #include <sys/uio.h>
    int readv(
      int s ,
      struct iovec *iov ,
      int iovcnt );

  PARAMETERS

    s        Represents a socket descriptor.

    iov      Points to an array of buffers to store the data in.

    iovcnt   Specifies the number of input buffers.

  DESCRIPTION

    The readv() function attempts to read data from the object referenced by
    the descriptor s.  The input data is scattered into the iovcnt buffers
    specified by the members of the iov array:  iov[0], iov[1], ... ,
    iov[iovcnt - 1]:

    The iovec structure is defined as

    struct iovec {
         caddr_t   iov_base;
         int       iov_len;
    };

    Each iovec entry specifies the base address and length of an area in
    memory where data should be placed.  The readv() function will always fill
    an area completely before proceeding to the next.

    If the returned value is 0, end-of-file has been reached.

  EXAMPLES

    To read an open socket from descriptor sd into buffers pointed to by iov:

    if (readv(sd, iov, iovcnt) == -1)



  2/94 - Intergraph Corporation                                              1

  readv(2)                            CLIX                            readv(2)



         perror("Readv failed");


  NOTES

    The readv() function is only supported on sockets, not on regular files.

  RETURN VALUES

    Upon successful completion, the number of bytes read is returned.
    Otherwise, a value of -1 is returned and errno is set to indicate the
    error.

  ERRORS

    The readv() function fails if one or more of the following is true:

    [EBADF]
           The descriptor is not valid.

    [ENOTSOCK]
           The descriptor references a file, not a socket.

    [EWOULDBLOCK]
           The socket is marked nonblocking and the requested operation would
           block.

    [EINTR]
           A signal was caught during the readv() function.

    [EFAULT]
           The address specified is not in a valid part of the user's address
           space.

    [ECONNRESET]
           The connection has been broken and there is no more data to read.

    [EINVAL]
           The maximum number of scatter gather locations has been exceeded.

  RELATED INFORMATION

    Functions:  fcntl(2), read(2), send(2), select(2), getsockopt(2),
    socket(2)










  2                                              Intergraph Corporation - 2/94