libstddjb
libskarnet
skalibs
Software
skarnet.org
The following functions are declared in the skalibs/genwrite.h header, and implemented in the libskarnet.a or libskarnet.so library.
genwrite is syntactic sugar to help write functions that might want to write either to memory or to a file descriptor.
Writing to memory is achieved via appending to a stralloc; writing to a file descriptor is achieved via appending to a buffer or a bufalloc.
A genwrite_t structure contains a pointer to a function that writes stuff to the target without flushing it (which can be genwrite_put_stralloc, genwrite_put_buffer, genwrite_put_bufalloc or any compatible user-defined function) in .put, a pointer to a function that flushes the target (which can be genwrite_flush_stralloc, genwrite_flush_buffer, genwrite_flush_bufalloc or any compatible user-defined function) in .flush, and a pointer to the target writing structure in .target.
Users should define a genwrite_t first, using the provided functions,
and give applications a pointer gp to this structure. To write len
characters at position s to the target, the application should then call
(*gp->put)(gp->target, s, len). When it is done writing, the
application should call (*gp->flush)(gp->target) to flush the
output.
genwrite_stdout and genwrite_stderr are predefined; they write to buffer_1 and buffer_2 respectively.
GENWRITE_STRALLOC_INIT(sa)
Declares a genwrite_t writing to the stralloc *sa.
GENWRITE_BUFFER_INIT(b)
Declares a genwrite_t writing to the buffer *b. Use
of such a buffer might interact badly with nonblocking I/O.
GENWRITE_BUFALLOC_INIT(ba)
Declares a genwrite_t writing to the bufalloc *ba.
Object-oriented programming in C is inefficient and cumbersome. It is usually possible to avoid it in Unix system programming, because Unix primitives are often generic enough. Unfortunately, it is not the case here: Unix does not provide an abstraction representing either a file or a memory buffer. So an object-oriented approach is unavoidable.