readv(2)
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readv System Call
Read from file.
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SYNTAX
#include <sys/types.h>
#include <sys/uio.h>
int readv (fildes, iov, iovent)
int fildes;
struct iovec iov[];
int iovent;
PARAMETERS
fildes An active, valid file descriptor.
iov An array of extents.
iovent The number of extents given.
DESCRIPTION
Readv transfers data from the object associated with <fildes>
into the <iovent> buffers specified by the members of <iov[]>:
iov[0], iov[1], ..., iov[iovent-1]. Each <iov[]> member
specifies the base address and length of an area in memory where
data should be placed. Readv fills an area completely before
proceeding to the next.
The iov structure is defined as:
struct iovec {
caddr_t iov_base;
int iov_len;
};
<Iovent> must be a positive number less than or equal to a
system-imposed limit guaranteed to be at least 16. The length of
each extent (iov_len) in <iov[]> must be non-negative and the sum
of these lengths must not overflow a `long'.
Except for the disposition of the data, readv is equivalent to
read.
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readv(2)
ACCESS CONTROL
<Fildes> must be open for reading.
RETURN VALUE
0..nbyte Completed successfully. The number of bytes
actually read is returned. The value 0 indicates
the `end-of-file' condition. Here, nbyte is the
sum of the lengths of the <iovent> extents given
in <iov[]>.
-1 An error occurred. Errno is set to indicate the
error.
EXCEPTIONS
Errno may be set to one of the following error codes:
EBADF <Fildes> is not a valid file descriptor open for
reading.
EFAULT <Iov> points outside the allocated address space.
EFAULT One or more of the <iov[]> members point outside
the allocated address space.
EINTR A signal was caught during the system call.
EINVAL <Iovent> was invalid.
EINVAL One or more of the iov_len values in <iov[]> was
negative.
EINVAL The sum of the iov_len values in <iov[]>
overflowed a `long'.
SEE ALSO
The related manual sections: creat(2), dup(2), dup2(2),
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readv(2)
fcntl(2), ioctl(2), open(2), pipe(2), read(2), select(2),
socket(2), socketpair(2),
termio(7).
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