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attempts to read of data from the object referenced by the descriptor
into the buffer pointed to by performs the same action, but scatters
the input data into the buffers specified by the members of the array:
iov[0], iov[1], ..., iov[iovcnt-1]. For the structure is defined as:
struct iovec { void *iov_base;
size_t iov_len;
}; Each entry specifies the base address and length of an area in
memory where data should be placed. will always fill an area completely
before proceeding to the next. On objects capable of seeking, the starts
at a position given by the pointer associated with (see Upon return from
the pointer is incremented by the number of bytes actually read. Objects
that are not capable of seeking always read from the current position.
The value of the pointer associated with such an object is undefined. Upon
successful completion, and return the number of bytes actually read and
placed in the buffer. The system guarantees to read the number of bytes
requested if the descriptor references a normal file that has that many
bytes left before the end-of-file, but in no other case.
If
successful, the number of bytes actually read is returned. Upon reading
end-of-file, zero is returned. Otherwise, a -1 is returned and the global variable
is set to indicate the error.
and will succeed unless: is not
a valid file or socket descriptor open for reading. points outside the
allocated address space. An I/O error occurred while reading from the file
system. A read from a slow device was interrupted before any data arrived
by the delivery of a signal. The pointer associated with was negative.
The file was marked for non-blocking I/O, and no data were ready to be
read. In addition, may return one of the following errors: was less
than or equal to 0, or greater than One of the values in the array
was negative. The sum of the values in the array overflowed a 32-bit integer.
Part of the points outside the process’s allocated address space.
The function is expected to conform to
The
function call appeared in The function call appeared in
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