x: Add x_fopencookie().

Implement x_fopencookie() in terms of either fopencookie or funopen, if
either is available.  If none of these calls are available, we don't
provide x_fopencookie().

This is a draft version, notably the mode field is ignored at the
moment.  Tests are also missing.

Author: lorinder

src/csnip/CMakeLists.txt

@@ -45,8 +45,16 @@ check_symbol_exists(clock_gettime "time.h"
 	CSNIP_CONF__HAVE_CLOCK_GETTIME)
 check_symbol_exists(flockfile "stdio.h"
 	CSNIP_CONF__HAVE_FLOCKFILE)
+set(CMAKE_REQUIRED_DEFINITIONS "-D_GNU_SOURCE")
+check_symbol_exists(fopencookie "stdio.h"
+	CSNIP_CONF__HAVE_FOPENCOOKIE)
+unset(CMAKE_REQUIRED_DEFINITIONS)
 check_symbol_exists(funlockfile "stdio.h"
 	CSNIP_CONF__HAVE_FUNLOCKFILE)
+set(CMAKE_REQUIRED_DEFINITIONS "-D_BSD_SOURCE")
+check_symbol_exists(funopen "stdio.h"
+	CSNIP_CONF__HAVE_FUNOPEN)
+unset(CMAKE_REQUIRED_DEFINITIONS)
 check_symbol_exists(getc_unlocked "stdio.h"
 	CSNIP_CONF__HAVE_GETC_UNLOCKED)
 check_symbol_exists(getdelim "stdio.h"
@@ -146,6 +154,7 @@ set(c_sources
 	util.c
 	x/asprintf.c
 	x/clock_gettime.c
+	x/fopencookie.c
 	x/getdelim.c
 	x/getline.c
 	x/getopt.c

src/csnip/csnip_conf.h.in

@@ -74,7 +74,9 @@
 #cmakedefine CSNIP_CONF__HAVE_ASPRINTF
 #cmakedefine CSNIP_CONF__HAVE_CLOCK_GETTIME
 #cmakedefine CSNIP_CONF__HAVE_FLOCKFILE
+#cmakedefine CSNIP_CONF__HAVE_FOPENCOOKIE
 #cmakedefine CSNIP_CONF__HAVE_FUNLOCKFILE
+#cmakedefine CSNIP_CONF__HAVE_FUNOPEN
 #cmakedefine CSNIP_CONF__HAVE_GETC_UNLOCKED
 #cmakedefine CSNIP_CONF__HAVE_GETDELIM
 #cmakedefine CSNIP_CONF__HAVE_GETLINE

src/csnip/x.h

@@ -78,6 +78,39 @@ int asprintf(char** strp, const char* fmt, ...);
 /**	Portable asprintf().  */
 int csnip_x_asprintf_imp(char** strp, const char* format, ...);
 
+/**	Wrapper for system fopencookie() or funopen(). */
+#if defined(CSNIP_CONF__HAVE_FOPENCOOKIE)
+typedef cookie_io_functions_t csnip_x_cookie_io_functions_t;
+
+FILE* csnip_x_fopencookie(void* __restrict__ cookie,
+			const char* __restrict__ mode,
+			csnip_x_cookie_io_functions_t funcs);
+#elif defined(CSNIP_CONF__HAVE_FUNOPEN)
+typedef csnip_x_ssize_t csnip_x_cookie_read_function_t(
+			void* cookie,
+			char* buf,
+			size_t size);
+typedef csnip_x_ssize_t csnip_x_cookie_write_function_t(
+			void* cookie,
+			const char* buf,
+			size_t size);
+typedef int csnip_x_cookie_seek_function_t(
+			void* cookie,
+			off_t* offset,
+			int whence);
+typedef int csnip_x_cookie_close_function_t(void* cookie);
+typedef struct {
+	csnip_x_cookie_read_function_t* read;
+	csnip_x_cookie_write_function_t* write;
+	csnip_x_cookie_seek_function_t* seek;
+	csnip_x_cookie_close_function_t* close;
+} csnip_x_cookie_io_functions_t;
+
+FILE* csnip_x_fopencookie(void* __restrict__ cookie,
+			const char* __restrict__ mode,
+			csnip_x_cookie_io_functions_t funcs);
+#endif
+
 /**	Wrapper for getdelim or csnip_x_getdelim_imp() */
 #define csnip_x_getdelim getdelim
 #if !defined(CSNIP_CONF__HAVE_GETDELIM)
@@ -308,13 +341,19 @@ int x_csnip_clock_gettime_imp(csnip_x_clockid_t clk_id,
 #ifdef CSNIP_X_CLOCK_MONOTONIC
 #define X_CLOCK_MONOTONIC		CSNIP_X_CLOCK_MONOTONIC
 #endif
+#define x_cookie_close_function_t	csnip_x_cookie_close_function_t
+#define x_cookie_io_functions_t		csnip_x_cookie_io_functions_t
+#define x_cookie_seek_function_t	csnip_x_cookie_seek_function_t
+#define x_cookie_read_function_t	csnip_x_cookie_read_function_t
+#define x_cookie_write_function_t	csnip_x_cookie_write_function_t
 #define X_CLOCK_REALTIME		CSNIP_X_CLOCK_REALTIME
 #define x_getdelim			csnip_x_getdelim
 #define x_getdelim_imp			csnip_x_getdelim_imp
 #define x_getline			csnip_x_getline
 #define x_getline_imp			csnip_x_getline_imp
 #define x_getopt			csnip_x_getopt
 #define x_getopt_imp			csnip_x_getopt_imp
+#define x_fopencookie			csnip_x_fopencookie
 #define x_iovec				csnip_x_iovec
 #define x_optarg			csnip_x_optarg
 #define x_optarg_imp			csnip_x_optarg_imp

src/csnip/x/fopencookie.c

@@ -0,0 +1,93 @@
+#define _GNU_SOURCE
+#define _DEFAULT_SOURCE
+
+#include <errno.h>
+
+#define CSNIP_SHORT_NAMES
+#include <csnip/mem.h>
+#include <csnip/x.h>
+
+#if defined(CSNIP_CONF__HAVE_FOPENCOOKIE)
+FILE* x_fopencookie(void* restrict cookie,
+			const char* restrict mode,
+			x_cookie_io_functions_t io_funcs)
+{
+	return fopencookie(cookie, mode, io_funcs);
+}
+
+#elif defined(CSNIP_CONF__HAVE_FUNOPEN)
+
+struct cookie_wrapper {
+	void* cookie;
+	x_cookie_io_functions_t io_funcs;
+};
+
+static int fun_read(void* cw_, char* buf, int sz)
+{
+	struct cookie_wrapper* cw = (struct cookie_wrapper*)cw_;
+	if (cw->io_funcs.read == NULL) {
+		/* Signal EOF */
+		errno = 0;
+		return 0;
+	} else {
+		return (*cw->io_funcs.read)(cw->cookie, buf, sz);
+	}
+}
+
+static int fun_write(void* cw_, const char* buf, int sz)
+{
+	struct cookie_wrapper* cw = (struct cookie_wrapper*)cw_;
+	if (cw->io_funcs.write == NULL) {
+		/* Discard data. */
+		return sz;
+	} else {
+		int r = (*cw->io_funcs.write)(cw->cookie, buf, sz);
+		return (r == 0 ? -1 : r);
+	}
+}
+
+static off_t fun_seek(void* cw_, off_t offs, int whence)
+{
+	struct cookie_wrapper* cw = (struct cookie_wrapper*)cw_;
+	const int r = (*cw->io_funcs.seek)(cw->cookie, &offs, whence);
+	if (r == -1)
+		return -1;
+	return offs;
+}
+
+static int fun_close(void* cw_)
+{
+	struct cookie_wrapper* cw = (struct cookie_wrapper*)cw_;
+	int r = 0;
+	if (cw->io_funcs.close != NULL) {
+		r = (*cw->io_funcs.close)(cw->cookie);
+	}
+	mem_Free(cw);
+	return r;
+}
+
+
+FILE* x_fopencookie(void* restrict cookie,
+			const char* restrict mode,
+			x_cookie_io_functions_t io_funcs)
+{
+	/* Create the cookie wrapper */
+	struct cookie_wrapper* wr;
+	int err = 0;
+	mem_Alloc(1, wr, err);
+	if (err != 0)
+		return NULL;
+	*wr = (struct cookie_wrapper){
+		.cookie = cookie,
+		.io_funcs = io_funcs,
+	};
+
+	(void)mode;
+	return funopen(wr,
+		fun_read,
+		fun_write,
+		io_funcs.seek != NULL ? fun_seek : NULL,
+		fun_close);
+
+}
+#endif