libstddjb
libskarnet
skalibs
Software
skarnet.org
The following functions are declared in the skalibs/allreadwrite.h header, and implemented in the libskarnet.a or libskarnet.so library.
allreadwrite is a set of IO function helpers. It's the basis for safe reading and writing, either in blocking or in non-blocking mode. The buffer interface relies heavily on allreadwrite.
Unless the IO you need is very simple, you generally should not be using the allreadwrite functions directly; you should use higher-level APIs such as bufalloc.
typedef int iofunc_t (int fd, char *buf, unsigned int len)
This is the simplified type of IO functions such as
read()
and
write().
Unless your system's int is 64-bit, skalibs - which has been
optimized for small systems - does not support IO operations of more than
2 GB of data, for the sake of simplicity. In any case, it's always
possible to send data in several smaller chunks.
typedef unsigned int alliofunc_t (int fd, char *buf, unsigned int len)
This is the type of an IO operation that expects all of its
len bytes to be sent or received, and that will loop around a
lower-level IO function until either len bytes have been
transmitted or an error has occurred. The return value is the actual
number of transmitted bytes; if this value is lesser than len,
it means that an error has occurred and errno is set.
int sanitize_read (int r)
Reading functions such as read() and fd_read return
a positive number when they succeed, -1 when they fail, and 0 when they
read an EOF. No data available on the descriptor when reading in
non-blocking mode is treated as a failure: -1 EWOULDBLOCK. But sometimes
(namely, in asynchronous IO loops) it's preferrable to handle EOF as an
exception condition and EWOULDBLOCK as a normal condition.
sanitize_read(), when applied to the result of a basic reading
function, returns 0 if r is -1 and errno is EWOULDBLOCK (or
EAGAIN). If r is zero, it returns -1 EPIPE. Else it returns r.
(No system reading function can ever set errno to EPIPE, and the semantics are appropriate, so EPIPE is a good candidate to signal EOF on reading.)
unsigned int allreadwrite (iofunc_t *f, int fd, char *s, unsigned int len)
*f must be a basic reading or writing function such as
fd_read or fd_write. allreadwrite() performs
*f on fd, s and len until len
bytes have been read or written, or until an error occurs. It returns the
total number of handled bytes, and sets errno if this number is not
len. allreadwrite may block if fd is in
blocking mode; if fd is in non-blocking mode, it might
set errno to EWOULDBLOCK or EAGAIN.
int fd_read (int fd, char *s, unsigned int len)
Safe wrapper around the
read()
function.
int fd_write (int fd, char const *s, unsigned int len)
Safe wrapper around the
write()
function.
int fd_recv (int fd, char *s, unsigned int len, unsigned int flags)
Safe wrapper around the
recv()
function.
int fd_send (int fd, char const *s, unsigned int len, unsigned int flags)
Safe wrapper around the
send()
function.
unsigned int allread (int fd, char *s, unsigned int len)
Equivalent to allreadwrite(&fd_read, fd, s, len) : attempts
to read len bytes from fd into s, looping around
fd_read() if necessary, until either len bytes are read or
an error occurs. EOF is reported as EPIPE.
unsigned int allwrite (int fd, char const *s, unsigned int len)
Equivalent to allreadwrite((iofunc_t *)&fd_write, fd, s, len) :
attempts to write len bytes from s to fd, looping
around fd_write() if necessary, until either len bytes are
written or an error occurs.