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readv (3)
NAME
readv, writev - read or write data into multiple buffers
SYNOPSIS
#include <sys/uio.h>
int readv(int filedes, const struct iovec *vector,
size_t count);
int writev(int filedes, const struct iovec *vector,
size_t count);
DESCRIPTION
The readv() function reads count blocks from the file associated with
the file descriptor filedes into the multiple buffers described by vec-
tor.
The writev() function writes at most count blocks described by vector
to the file associated with the file descriptor filedes.
The pointer vector points to a struct iovec defined in <sys/uio.h> as
struct iovec {
void *iov_base; /* Starting address */
size_t iov_len; /* Number of bytes */
};
Buffers are processed in the order vector[0], vector[1], ... vec-
tor[count].
The readv() function works just like read(2) except that multiple
buffers are filled.
The writev() function works just like write(2) except that multiple
buffers are written out.
RETURN VALUE
The readv() function returns the number of bytes or -1 on error; the
writev() function returns the number of bytes written.
ERRORS
The readv() and writev() functions can fail and set errno to the fol-
lowing values:
EBADF fd is not a valid file descriptor.
EINVAL fd is unsuitable for reading (for readv()) or writing (for
writev()).
EFAULT buf is outside the processes' address space.
EAGAIN Non-blocking I/O had been selected in the open() call, and read-
ing or writing could not be done immediately.
library; the results will be undefined and probably not what you want.
SEE ALSO
read(2), write(2)
GNU 1993-04-25 readv(3)