Add an implementation based on tedu@'s design of fmemopen(3) and

open_memstream(3) so they can be polished in-tree.

One of the manpages comes from NetBSD with some tweaks.

Prodded by espie@, krw@, guenther@

1 files changed, 186 insertions, 0 deletions

diff --git a/lib/libc/stdio/fmemopen.c b/lib/libc/stdio/fmemopen.c
new file mode 100644
index 00000000000..fd76f625b23
--- /dev/null
+++ b/lib/libc/stdio/fmemopen.c
@@ -0,0 +1,186 @@
+/*	$OpenBSD: fmemopen.c,v 1.1 2013/01/01 17:41:13 mpi Exp $	*/
+/*
+ * Copyright (c) 2011 Martin Pieuchot <mpi@openbsd.org>
+ * Copyright (c) 2009 Ted Unangst
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "local.h"
+
+struct state {
+	char		*string;	/* actual stream */
+	size_t		 pos;		/* current position */
+	size_t		 size;		/* allocated size */
+	size_t		 len;		/* length of the data */
+};
+
+static int
+fmemopen_read(void *v, char *b, int l)
+{
+	struct state	*st = v;
+	int		 i;
+
+	for (i = 0; i < l && i + st->pos < st->len; i++)
+		b[i] = st->string[st->pos + i];
+	st->pos += i;
+
+	return (i);
+}
+
+static int
+fmemopen_write(void *v, const char *b, int l)
+{
+	struct state	*st = v;
+	int		i;
+
+	for (i = 0; i < l && i + st->pos < st->size; i++)
+		st->string[st->pos + i] = b[i];
+	st->pos += i;
+
+	if (st->pos >= st->len) {
+		st->len = st->pos;
+
+		if (st->len == st->size)
+			st->string[st->len - 1] = '\0';
+		else
+			st->string[st->len] = '\0';
+	}
+
+	return (i);
+}
+
+static fpos_t
+fmemopen_seek(void *v, fpos_t pos, int whence)
+{
+	struct state	*st = v;
+
+	switch (whence) {
+	case SEEK_SET:
+		break;
+	case SEEK_CUR:
+		pos += st->pos;
+		break;
+	case SEEK_END:
+		/*
+		 * XXX The standard is not clear about where to seek
+		 * from the end of the data or the end of the buffer.
+		 */
+		pos += st->len;
+		break;
+	default:
+		errno = EINVAL;
+		return (-1);
+	}
+
+	if (pos < 0 || pos > st->size)
+		return (-1);
+
+	st->pos = pos;
+
+	return (pos);
+}
+
+static int
+fmemopen_close(void *v)
+{
+	free(v);
+
+	return (0);
+}
+
+static int
+fmemopen_close_free(void *v)
+{
+	struct state	*st = v;
+
+	free(st->string);
+	free(st);
+
+	return (0);
+}
+
+FILE *
+fmemopen(void *buf, size_t size, const char *mode)
+{
+	struct state	*st;
+	FILE		*fp;
+	int		 flags, oflags;
+
+	if (size == 0) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	if ((flags = __sflags(mode, &oflags)) == 0) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	if (buf == NULL && ((oflags & O_RDWR) == 0)) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	if ((st = malloc(sizeof(*st))) == NULL)
+		return (NULL);
+
+	if ((fp = __sfp()) == NULL) {
+		free(st);
+		return (NULL);
+	}
+
+	st->pos = 0;
+	st->len = 0;
+	st->size = size;
+
+	if (buf == NULL) {
+		if ((st->string = malloc(size)) == NULL) {
+			free(st);
+			fp->_flags = 0;
+			return (NULL);
+		}
+		*st->string = '\0';
+	} else {
+		st->string = (char *)buf;
+
+		if ((oflags & O_WRONLY) == 0)
+			st->len = size;
+
+		if (oflags & O_TRUNC)
+			*st->string = '\0';
+
+		if (oflags & O_APPEND) {
+			char	*p;
+
+			if ((p = memchr(st->string, '\0', size)) != NULL)
+				st->pos = st->len = (p - st->string);
+			else
+				st->pos = st->len = size;
+		}
+	}
+
+	fp->_flags = (short)flags;
+	fp->_file = -1;
+	fp->_cookie = (void *)st;
+	fp->_read = (flags & __SWR) ? NULL : fmemopen_read;
+	fp->_write = (flags & __SRD) ? NULL : fmemopen_write;
+	fp->_seek = fmemopen_seek;
+	fp->_close = (buf == NULL) ? fmemopen_close_free : fmemopen_close;
+
+	return (fp);
+}