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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /stdio/memstream.c
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initial import
Diffstat (limited to 'stdio/memstream.c')
-rw-r--r--stdio/memstream.c177
1 files changed, 177 insertions, 0 deletions
diff --git a/stdio/memstream.c b/stdio/memstream.c
new file mode 100644
index 0000000..704eca5
--- /dev/null
+++ b/stdio/memstream.c
@@ -0,0 +1,177 @@
+/* Copyright (C) 1991, 1992, 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct memstream_info
+ {
+ char **buffer;
+ size_t *bufsize;
+ };
+
+/* Enlarge STREAM's buffer. */
+static void
+DEFUN(enlarge_buffer, (stream, c),
+ register FILE *stream AND int c)
+{
+ struct memstream_info *info = (struct memstream_info *) stream->__cookie;
+ size_t need;
+
+ if (stream->__put_limit != stream->__buffer)
+ /* Record how much has actually been written into the buffer. */
+ *info->bufsize = stream->__bufp - stream->__buffer;
+
+ if (stream->__target != -1
+ && stream->__target > *info->bufsize)
+ /* Our target (where the buffer maps to) is always zero except when
+ the user just did a SEEK_END fseek. If he sought within the
+ buffer, we need do nothing and will zero the target below. If he
+ sought past the end of the object, grow and zero-fill the buffer
+ up to the target address. */
+ need = stream->__target;
+ else
+ need = *info->bufsize;
+
+ /* We always need an extra character in the buffer. Either we are
+ writing C, or we are flushing and need to write a NUL terminator. */
+ ++need;
+
+ if (stream->__bufsize < need)
+ {
+ /* Enlarge the buffer. */
+ char *newbuf;
+ size_t newsize;
+ if (stream->__bufsize * 2 < need)
+ newsize = need;
+ else
+ newsize = stream->__bufsize * 2;
+ newbuf = (char *) realloc ((PTR) stream->__buffer, newsize);
+ if (newbuf == NULL)
+ {
+ stream->__error = 1;
+ return;
+ }
+ *info->buffer = stream->__buffer = newbuf;
+ stream->__bufsize = newsize;
+ }
+
+ stream->__target = stream->__offset = 0;
+ stream->__get_limit = stream->__bufp = stream->__buffer + *info->bufsize;
+ stream->__put_limit = stream->__buffer + stream->__bufsize;
+
+ need -= stream->__bufp - stream->__buffer + 1;
+ if (need > 0)
+ {
+ /* We are extending the buffer after an fseek; zero-fill new space. */
+ bzero (stream->__bufp, need);
+ stream->__bufp += need;
+ }
+
+ if (c != EOF)
+ *stream->__bufp++ = (unsigned char) c;
+ else
+ *stream->__bufp = '\0';
+}
+
+/* Seek function for memstreams.
+ There is no external state to munge. */
+
+static int
+DEFUN(seek, (cookie, pos, whence),
+ PTR cookie AND fpos_t *pos AND int whence)
+{
+ switch (whence)
+ {
+ case SEEK_SET:
+ case SEEK_CUR:
+ return 0;
+
+ case SEEK_END:
+ /* Return the position relative to the end of the object.
+ fseek has just flushed us, so the info is consistent. */
+ *pos += *((struct memstream_info *) cookie)->bufsize;
+ return 0;
+
+ default:
+ __libc_fatal ("memstream::seek called with bogus WHENCE\n");
+ return -1;
+ }
+}
+
+static int
+DEFUN(free_info, (cookie), PTR cookie)
+{
+#if 0
+ struct memstream_info *info = (struct memstream_info *) cookie;
+ char *buf;
+
+ buf = (char *) realloc ((PTR) *info->buffer, *info->bufsize);
+ if (buf != NULL)
+ *info->buffer = buf;
+#endif
+
+ free (cookie);
+
+ return 0;
+}
+
+/* Open a stream that writes into a malloc'd buffer that is expanded as
+ necessary. *BUFLOC and *SIZELOC are updated with the buffer's location
+ and the number of characters written on fflush or fclose. */
+FILE *
+DEFUN(open_memstream, (bufloc, sizeloc),
+ char **bufloc AND size_t *sizeloc)
+{
+ FILE *stream;
+ struct memstream_info *info;
+
+ if (bufloc == NULL || sizeloc == NULL)
+ {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ stream = fmemopen ((char *) NULL, BUFSIZ, "w+");
+ if (stream == NULL)
+ return NULL;
+
+ info = (struct memstream_info *) malloc (sizeof (struct memstream_info));
+ if (info == NULL)
+ {
+ int save = errno;
+ (void) fclose (stream);
+ errno = save;
+ return NULL;
+ }
+
+ stream->__room_funcs.__output = enlarge_buffer;
+ stream->__io_funcs.__seek = seek;
+ stream->__io_funcs.__close = free_info;
+ stream->__cookie = (PTR) info;
+ stream->__userbuf = 1;
+
+ info->buffer = bufloc;
+ info->bufsize = sizeloc;
+
+ *bufloc = stream->__buffer;
+
+ return stream;
+}