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da39102216
* common/membuf.c (set_membuf_err): New.
246 lines
5.6 KiB
C
246 lines
5.6 KiB
C
/* membuf.c - A simple implementation of a dynamic buffer.
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* Copyright (C) 2001, 2003, 2009, 2011 Free Software Foundation, Inc.
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* Copyright (C) 2013 Werner Koch
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*
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* This file is part of GnuPG.
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of either
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*
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* - the GNU Lesser General Public License as published by the Free
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* Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* or
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*
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* - the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* or both in parallel, as here.
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*
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* This file is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <stdarg.h>
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#include "util.h"
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#include "membuf.h"
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/* A simple implementation of a dynamic buffer. Use init_membuf() to
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create a buffer, put_membuf to append bytes and get_membuf to
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release and return the buffer. Allocation errors are detected but
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only returned at the final get_membuf(), this helps not to clutter
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the code with out of core checks. */
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void
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init_membuf (membuf_t *mb, int initiallen)
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{
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mb->len = 0;
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mb->size = initiallen;
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mb->out_of_core = 0;
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mb->buf = xtrymalloc (initiallen);
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if (!mb->buf)
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mb->out_of_core = errno;
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}
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/* Same as init_membuf but allocates the buffer in secure memory. */
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void
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init_membuf_secure (membuf_t *mb, int initiallen)
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{
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mb->len = 0;
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mb->size = initiallen;
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mb->out_of_core = 0;
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mb->buf = xtrymalloc_secure (initiallen);
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if (!mb->buf)
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mb->out_of_core = errno;
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}
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/* Shift the content of the membuf MB by AMOUNT bytes. The next
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operation will then behave as if AMOUNT bytes had not been put into
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the buffer. If AMOUNT is greater than the actual accumulated
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bytes, the membuf is basically reset to its initial state. */
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void
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clear_membuf (membuf_t *mb, size_t amount)
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{
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/* No need to clear if we are already out of core. */
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if (mb->out_of_core)
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return;
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if (amount >= mb->len)
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mb->len = 0;
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else
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{
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mb->len -= amount;
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memmove (mb->buf, mb->buf+amount, mb->len);
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}
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}
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void
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put_membuf (membuf_t *mb, const void *buf, size_t len)
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{
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if (mb->out_of_core || !len)
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return;
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if (mb->len + len >= mb->size)
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{
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char *p;
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mb->size += len + 1024;
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p = xtryrealloc (mb->buf, mb->size);
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if (!p)
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{
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mb->out_of_core = errno ? errno : ENOMEM;
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/* Wipe out what we already accumulated. This is required
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in case we are storing sensitive data here. The membuf
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API does not provide another way to cleanup after an
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error. */
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wipememory (mb->buf, mb->len);
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return;
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}
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mb->buf = p;
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}
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if (buf)
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memcpy (mb->buf + mb->len, buf, len);
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else
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memset (mb->buf + mb->len, 0, len);
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mb->len += len;
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}
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/* A variant of put_membuf accepting a void * and returning a
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gpg_error_t (which will always return 0) to be used as a generic
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callback handler. This function also allows buffer to be NULL. */
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gpg_error_t
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put_membuf_cb (void *opaque, const void *buf, size_t len)
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{
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membuf_t *data = opaque;
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if (buf)
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put_membuf (data, buf, len);
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return 0;
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}
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void
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put_membuf_str (membuf_t *mb, const char *string)
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{
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put_membuf (mb, string, strlen (string));
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}
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void
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put_membuf_printf (membuf_t *mb, const char *format, ...)
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{
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int rc;
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va_list arg_ptr;
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char *buf;
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va_start (arg_ptr, format);
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rc = gpgrt_vasprintf (&buf, format, arg_ptr);
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if (rc < 0)
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mb->out_of_core = errno ? errno : ENOMEM;
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va_end (arg_ptr);
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if (rc >= 0)
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{
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put_membuf (mb, buf, strlen (buf));
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xfree (buf);
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}
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}
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void *
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get_membuf (membuf_t *mb, size_t *len)
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{
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char *p;
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if (mb->out_of_core)
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{
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if (mb->buf)
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{
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wipememory (mb->buf, mb->len);
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xfree (mb->buf);
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mb->buf = NULL;
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}
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gpg_err_set_errno (mb->out_of_core);
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return NULL;
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}
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p = mb->buf;
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if (len)
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*len = mb->len;
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mb->buf = NULL;
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mb->out_of_core = ENOMEM; /* hack to make sure it won't get reused. */
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return p;
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}
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/* Same as get_membuf but shrinks the reallocated space to the
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required size. */
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void *
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get_membuf_shrink (membuf_t *mb, size_t *len)
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{
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void *p, *pp;
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size_t dummylen;
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if (!len)
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len = &dummylen;
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p = get_membuf (mb, len);
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if (!p)
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return NULL;
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if (*len)
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{
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pp = xtryrealloc (p, *len);
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if (pp)
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p = pp;
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}
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return p;
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}
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/* Peek at the membuf MB. On success a pointer to the buffer is
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returned which is valid until the next operation on MB. If LEN is
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not NULL the current LEN of the buffer is stored there. On error
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NULL is returned and ERRNO is set. */
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const void *
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peek_membuf (membuf_t *mb, size_t *len)
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{
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const char *p;
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if (mb->out_of_core)
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{
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gpg_err_set_errno (mb->out_of_core);
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return NULL;
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}
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p = mb->buf;
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if (len)
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*len = mb->len;
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return p;
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}
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/* To assist using membuf with function returning an error, this
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* function sets the membuf into the error state. */
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void
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set_membuf_err (membuf_t *mb, gpg_error_t err)
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{
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if (!mb->out_of_core)
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{
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int myerr = gpg_err_code_to_errno (gpg_err_code (err));
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mb->out_of_core = myerr? myerr : EINVAL;
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}
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}
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