Update.

	* libio/stdio.h: Add fmemopen prototype.

2000-08-25  Andreas Jaeger  <aj@suse.de>

	* libio/Makefile (routines): Add fmemopen.
	(tests): Add test-fmemopen.
	* libio/Versions: Add fmemopen with version GLIBC_2.2.
	* libio/test-fmemopen.c: New file.
	* libio/fmemopen.c: New file.
	Patches by Hanno Mueller <kontakt@hanno.de>.

2000-08-28  Ulrich Drepper  <drepper@redhat.com>

1 files changed, 242 insertions, 0 deletions

diff --git a/libio/fmemopen.c b/libio/fmemopen.c
new file mode 100644
index 0000000..d98b671
--- /dev/null
+++ b/libio/fmemopen.c
@@ -0,0 +1,242 @@
+/* Fmemopen implementation.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by  Hanno Mueller, kontakt@hanno.de, 2000.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/*
+ * fmemopen() - "my" version of a string stream
+ * Hanno Mueller, kontakt@hanno.de
+ *
+ *
+ * I needed fmemopen() for an application that I currently work on,
+ * but couldn't find it in libio. The following snippet of code is an
+ * attempt to implement what glibc's documentation describes.
+ *
+ * No, it isn't really tested yet. :-)
+ *
+ *
+ *
+ * I already see some potential problems:
+ *
+ * - I never used the "original" fmemopen(). I am sure that "my"
+ *   fmemopen() behaves differently than the original version.
+ *
+ * - The documentation doesn't say wether a string stream allows
+ *   seeks. I checked the old fmemopen implementation in glibc's stdio
+ *   directory, wasn't quite able to see what is going on in that
+ *   source, but as far as I understand there was no seek there. For
+ *   my application, I needed fseek() and ftell(), so it's here.
+ *
+ * - "append" mode and fseek(p, SEEK_END) have two different ideas
+ *   about the "end" of the stream.
+ *
+ *   As described in the documentation, when opening the file in
+ *   "append" mode, the position pointer will be set to the first null
+ *   character of the string buffer (yet the buffer may already
+ *   contain more data). For fseek(), the last byte of the buffer is
+ *   used as the end of the stream.
+ *
+ * - It is unclear to me what the documentation tries to say when it
+ *   explains what happens when you use fmemopen with a NULL
+ *   buffer.
+ *
+ *   Quote: "fmemopen [then] allocates an array SIZE bytes long. This
+ *   is really only useful if you are going to write things to the
+ *   buffer and then read them back in again."
+ *
+ *   What does that mean if the original fmemopen() did not allow
+ *   seeking? How do you read what you just wrote without seeking back
+ *   to the beginning of the stream?
+ *
+ * - I think there should be a second version of fmemopen() that does
+ *   not add null characters for each write. (At least in my
+ *   application, I am not actually using strings but binary data and
+ *   so I don't need the stream to add null characters on its own.)
+ */
+
+#include <libio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+typedef struct fmemopen_cookie_struct fmemopen_cookie_t;
+struct fmemopen_cookie_struct
+{
+  char *buffer;
+  int mybuffer;
+  size_t size;
+  _IO_off64_t pos;
+  size_t maxpos;
+};
+
+
+ssize_t
+fmemopen_read (void *cookie, char *b, size_t s)
+{
+  fmemopen_cookie_t *c;
+
+  c = (fmemopen_cookie_t *) cookie;
+
+  if ((c->pos + s) > c->size)
+    {
+      if (c->pos == c->size)
+	return -1;
+      s = c->size - c->pos;
+    }
+
+  memcpy (b, &(c->buffer[c->pos]), s);
+
+  c->pos += s;
+  if (c->pos > c->maxpos)
+    c->maxpos = c->pos;
+
+  return s;
+}
+
+
+ssize_t
+fmemopen_write (void *cookie, const char *b, size_t s)
+{
+  fmemopen_cookie_t *c;
+  int addnullc;
+
+  c = (fmemopen_cookie_t *) cookie;
+
+  addnullc = ((s == 0) || (b[s - 1] != '\0')) ? 1 : 0;
+
+  if ((c->pos + s + addnullc) > c->size)
+    {
+      if ((c->pos + addnullc) == c->size)
+	return -1;
+      s = c->size - c->pos - addnullc;
+    }
+
+  memcpy (&(c->buffer[c->pos]), b, s);
+
+  c->pos += s;
+  if (c->pos > c->maxpos)
+    {
+      c->maxpos = c->pos;
+      if (addnullc)
+	c->buffer[c->maxpos] = '\0';
+    }
+
+  return s;
+}
+
+
+int
+fmemopen_seek (void *cookie, _IO_off64_t * p, int w)
+{
+  _IO_off64_t np;
+  fmemopen_cookie_t *c;
+
+  c = (fmemopen_cookie_t *) cookie;
+
+  switch (w)
+    {
+
+    case SEEK_SET:
+      np = *p;
+      break;
+
+    case SEEK_CUR:
+      np = c->pos + *p;
+      break;
+
+    case SEEK_END:
+      np = c->size - *p;
+      break;
+
+    }
+
+  if ((np < 0) || (np > c->size))
+    return -1;
+
+  c->pos = np;
+
+  return np;
+}
+
+
+int
+fmemopen_close (void *cookie)
+{
+  fmemopen_cookie_t *c;
+
+  c = (fmemopen_cookie_t *) cookie;
+
+  if (c->mybuffer)
+    free (c->buffer);
+  free (c);
+
+  return 0;
+}
+
+
+FILE *
+fmemopen (void *buf, size_t len, const char *mode)
+{
+  cookie_io_functions_t iof;
+  fmemopen_cookie_t *c;
+
+  c = (fmemopen_cookie_t *) malloc (sizeof (fmemopen_cookie_t));
+  if (c == NULL)
+    return NULL;
+
+  c->mybuffer = (buf == NULL);
+
+  if (c->mybuffer)
+    {
+      c->buffer = (char *) malloc (len);
+      if (c->buffer == NULL)
+	{
+	  free (c);
+	  return NULL;
+	}
+      c->buffer[0] = '\0';
+    }
+  else
+    {
+      c->buffer = buf;
+    }
+
+  c->size = len;
+
+  if (mode[0] == 'w')
+    c->buffer[0] = '\0';
+
+  c->maxpos = strlen (c->buffer);
+
+  if (mode[0] == 'a')
+    {
+      c->pos = c->maxpos;
+    }
+  else
+    {
+      c->pos = 0;
+    }
+
+  iof.read = fmemopen_read;
+  iof.write = fmemopen_write;
+  iof.seek = fmemopen_seek;
+  iof.close = fmemopen_close;
+
+  return fopencookie (c, mode, iof);
+}