223 lines
7.4 KiB
C
223 lines
7.4 KiB
C
/*
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* Copyright (C) 2022-2024 Jordan Bancino <@jordan:bancino.net>
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef CYTOPLASM_IO_H
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#define CYTOPLASM_IO_H
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/***
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* @Nm Io
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* @Nd Source/sink-agnostic I/O for implementing custom streams.
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* @Dd April 29 2023
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* @Xr Stream Tls
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*
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* Many systems provide platform-specific means of implementing custom
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* streams using file pointers. However, POSIX does not define a way
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* of programmatically creating custom streams.
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* .Nm
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* therefore fills this gap in POSIX by mimicking all of the
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* functionality of these platform-specific functions, but in pure
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* POSIX C. It defines a number of callback funtions to be executed
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* in place of the standard POSIX I/O functions, which are used to
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* implement arbitrary streams that may not be to a file or socket.
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* Additionally, streams can now be pipelined; the sink of one stream
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* may be the source of another lower-level stream. Additionally, all
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* streams, regardless of their source or sink, share the same API, so
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* streams can be handled in a much more generic manner. This allows
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* the HTTP client and server libraries to seemlessly support TLS and
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* plain connections without having to handle each separately.
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* .Pp
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* .Nm
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* was heavily inspired by GNU's
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* .Fn fopencookie
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* and BSD's
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* .Fn funopen .
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* It aims to combine the best of both of these functions into a single
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* API that is intuitive and easy to use.
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <sys/types.h>
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#ifndef IO_BUFFER
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#define IO_BUFFER 4096
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#endif
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/**
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* An opaque structure analogous to a POSIX file descriptor.
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*/
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typedef struct Io Io;
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/**
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* Read input from the source of a stream. This function should
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* attempt to read the specified number of bytes of data from the
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* given cookie into the given buffer. It should behave identically
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* to the POSIX
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* .Xr read 2
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* system call, except instead of using an integer descriptor as the
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* first parameter, a pointer to an implementation-defined cookie
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* stores any information the function needs to read from the source.
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*/
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typedef ssize_t (IoReadFunc) (void *, void *, size_t);
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/**
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* Write output to a sink. This function should attempt to write the
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* specified number of bytes of data from the given buffer into the
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* stream described by the given cookie. It should behave identically
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* to the POSIX
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* .Xr write 2
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* system call, except instead of using an integer descriptor as the
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* first parameter, a pointer to an implementation-defined cookie
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* stores any information the function needs to write to the sink.
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*/
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typedef ssize_t (IoWriteFunc) (void *, void *, size_t);
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/**
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* Repositions the offset of the stream described by the specified
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* cookie. This function should behave identically to the POSIX
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* .Xr lseek 2
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* system call, except instead of using an integer descriptor as the
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* first parameter, a pointer to an implementation-defined cookie
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* stores any information the function needs to seek the stream.
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*/
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typedef off_t (IoSeekFunc) (void *, off_t, int);
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/**
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* Close the given stream, making future reads or writes result in
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* undefined behavior. This function should also free all memory
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* associated with the cookie. It should behave identically to the
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* .Xr close 2
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* system call, except instead of using an integer descriptor for the
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* parameter, a pointer to an implementation-defined cookie stores any
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* information the function needs to close the stream.
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*/
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typedef int (IoCloseFunc) (void *);
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/**
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* A simple mechanism for grouping together a set of stream functions,
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* to be passed to
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* .Fn IoCreate .
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*/
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typedef struct IoFunctions
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{
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IoReadFunc *read;
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IoWriteFunc *write;
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IoSeekFunc *seek;
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IoCloseFunc *close;
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} IoFunctions;
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/**
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* Create a new stream using the specified cookie and the specified
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* I/O functions.
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*/
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extern Io * IoCreate(void *, IoFunctions);
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/**
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* Read the specified number of bytes from the specified stream into
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* the specified buffer. This calls the stream's underlying IoReadFunc,
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* which should behave identically to the POSIX
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* .Xr read 2
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* system call.
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*/
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extern ssize_t IoRead(Io *, void *, size_t);
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/**
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* Write the specified number of bytes from the specified stream into
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* the specified buffer. This calls the stream's underlying
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* IoWriteFunc, which should behave identically to the POSIX
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* .Xr write 2
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* system call.
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*/
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extern ssize_t IoWrite(Io *, void *, size_t);
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/**
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* Seek the specified stream using the specified offset and whence
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* value. This calls the stream's underlying IoSeekFunc, which should
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* behave identically to the POSIX
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* .Xr lseek 2
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* system call.
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*/
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extern off_t IoSeek(Io *, off_t, int);
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/**
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* Close the specified stream. This calls the stream's underlying
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* IoCloseFunc, which should behave identically to the POSIX
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* .Xr close 2
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* system call.
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*/
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extern int IoClose(Io *);
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/**
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* Print a formatted string to the given stream. This is a
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* re-implementation of the standard library function
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* .Xr vfprintf 3 ,
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* and behaves identically.
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*/
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extern int IoVprintf(Io *, const char *, va_list);
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/**
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* Print a formatted string to the given stream. This is a
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* re-implementation of the standard library function
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* .Xr fprintf 3 ,
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* and behaves identically.
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*/
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extern int IoPrintf(Io *, const char *,...);
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/**
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* Read all the bytes from the first stream and write them to the
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* second stream. Neither stream is closed upon the completion of this
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* function. This can be used for quick and convenient buffered
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* copying of data from one stream into another.
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*/
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extern ssize_t IoCopy(Io *, Io *);
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/**
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* Wrap a POSIX file descriptor to take advantage of this API. The
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* common use case for this function is when a regular file descriptor
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* needs to be accessed by an application that uses this API to also
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* access non-POSIX streams.
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*/
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extern Io * IoFd(int);
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/**
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* Open or create a file for reading or writing. The specified file
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* name is opened for reading or writing as specified by the given
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* flags and mode. This function is a simple convenience wrapper around
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* the POSIX
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* .Xr open 2
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* system call that passes the opened file descriptor into
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* .Fn IoFd .
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*/
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extern Io * IoOpen(const char *, int, mode_t);
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/**
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* Wrap a standard C file pointer to take advantage of this API. The
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* common use case for this function is when a regular C file pointer
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* needs to be accessed by an application that uses this API to also
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* access custom streams.
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*/
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extern Io * IoFile(FILE *);
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#endif /* CYTOPLASM_IO_H */
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