libc: Add fopencookie(3) wrapper around funopen(3)

Reviewed by:	jhb, oshogbo
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D6282

1 files changed, 168 insertions, 0 deletions

diff --git a/lib/libc/stdio/fopencookie.c b/lib/libc/stdio/fopencookie.c
new file mode 100644
index 0000000..6dc3953
--- /dev/null
+++ b/lib/libc/stdio/fopencookie.c
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2016, EMC / Isilon Storage Division
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
+ * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/fcntl.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "local.h"
+
+struct fopencookie_thunk {
+	void			*foc_cookie;
+	cookie_io_functions_t	foc_io;
+};
+
+static int _fopencookie_read(void *, char *, int);
+static int _fopencookie_write(void *, const char *, int);
+static fpos_t _fopencookie_seek(void *, fpos_t, int);
+static int _fopencookie_close(void *);
+
+FILE *
+fopencookie(void *cookie, const char *mode, cookie_io_functions_t io_funcs)
+{
+	int (*readfn)(void *, char *, int);
+	int (*writefn)(void *, const char *, int);
+	struct fopencookie_thunk *thunk;
+	FILE *fp;
+	int flags, oflags;
+
+	if ((flags = __sflags(mode, &oflags)) == 0)
+		return (NULL);
+
+	thunk = malloc(sizeof(*thunk));
+	if (thunk == NULL)
+		return (NULL);
+
+	thunk->foc_cookie = cookie;
+	thunk->foc_io = io_funcs;
+
+	readfn = _fopencookie_read;
+	writefn = _fopencookie_write;
+	if (flags == __SWR)
+		readfn = NULL;
+	else if (flags == __SRD)
+		writefn = NULL;
+
+	fp = funopen(thunk, readfn, writefn, _fopencookie_seek,
+	    _fopencookie_close);
+	if (fp == NULL) {
+		free(thunk);
+		return (NULL);
+	}
+
+	if ((oflags & O_APPEND) != 0)
+		fp->_flags |= __SAPP;
+
+	return (fp);
+}
+
+static int
+_fopencookie_read(void *cookie, char *buf, int size)
+{
+	struct fopencookie_thunk *thunk;
+
+	thunk = cookie;
+
+	/* Reads from a stream with NULL read return EOF. */
+	if (thunk->foc_io.read == NULL)
+		return (0);
+
+	return ((int)thunk->foc_io.read(thunk->foc_cookie, buf, (size_t)size));
+}
+
+static int
+_fopencookie_write(void *cookie, const char *buf, int size)
+{
+	struct fopencookie_thunk *thunk;
+
+	thunk = cookie;
+
+	/* Writes to a stream with NULL write discard data. */
+	if (thunk->foc_io.write == NULL)
+		return (size);
+
+	return ((int)thunk->foc_io.write(thunk->foc_cookie, buf,
+		(size_t)size));
+}
+
+static fpos_t
+_fopencookie_seek(void *cookie, fpos_t offset, int whence)
+{
+	struct fopencookie_thunk *thunk;
+	off64_t off64;
+	int res;
+
+	switch (whence) {
+	case SEEK_SET:
+	case SEEK_CUR:
+	case SEEK_END:
+		break;
+	default:
+		/* fopencookie(3) only allows these three seek modes. */
+		errno = EINVAL;
+		return (-1);
+	}
+
+	thunk = cookie;
+
+	/*
+	 * If seek is NULL, it is not possible to perform seek operations on
+	 * the stream.
+	 */
+	if (thunk->foc_io.seek == NULL) {
+		errno = ENOTSUP;
+		return (-1);
+	}
+
+	off64 = (off64_t)offset;
+	res = thunk->foc_io.seek(thunk->foc_cookie, &off64, whence);
+	if (res < 0)
+		return (res);
+
+	return ((fpos_t)off64);
+}
+
+static int
+_fopencookie_close(void *cookie)
+{
+	struct fopencookie_thunk *thunk;
+	int ret, serrno;
+
+	ret = 0;
+	thunk = cookie;
+	if (thunk->foc_io.close != NULL)
+		ret = thunk->foc_io.close(thunk->foc_cookie);
+
+	serrno = errno;
+	free(thunk);
+	errno = serrno;
+	return (ret);
+}