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Diffstat (limited to 'common/membuf.c')
| -rw-r--r-- | common/membuf.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/common/membuf.c b/common/membuf.c new file mode 100644 index 0000000..009fbc3 --- /dev/null +++ b/common/membuf.c @@ -0,0 +1,233 @@ +/* membuf.c - A simple implementation of a dynamic buffer. + * Copyright (C) 2001, 2003, 2009, 2011 Free Software Foundation, Inc. + * Copyright (C) 2013 Werner Koch + * + * This file is part of GnuPG. + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of either + * + * - the GNU Lesser General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at + * your option) any later version. + * + * or + * + * - the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at + * your option) any later version. + * + * or both in parallel, as here. + * + * This file 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <https://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdlib.h> +#include <errno.h> +#include <stdarg.h> + +#include "util.h" +#include "membuf.h" + + +/* A simple implementation of a dynamic buffer. Use init_membuf() to + create a buffer, put_membuf to append bytes and get_membuf to + release and return the buffer. Allocation errors are detected but + only returned at the final get_membuf(), this helps not to clutter + the code with out of core checks. */ + +void +init_membuf (membuf_t *mb, int initiallen) +{ + mb->len = 0; + mb->size = initiallen; + mb->out_of_core = 0; + mb->buf = xtrymalloc (initiallen); + if (!mb->buf) + mb->out_of_core = errno; +} + +/* Same as init_membuf but allocates the buffer in secure memory. */ +void +init_membuf_secure (membuf_t *mb, int initiallen) +{ + mb->len = 0; + mb->size = initiallen; + mb->out_of_core = 0; + mb->buf = xtrymalloc_secure (initiallen); + if (!mb->buf) + mb->out_of_core = errno; +} + + +/* Shift the content of the membuf MB by AMOUNT bytes. The next + operation will then behave as if AMOUNT bytes had not been put into + the buffer. If AMOUNT is greater than the actual accumulated + bytes, the membuf is basically reset to its initial state. */ +void +clear_membuf (membuf_t *mb, size_t amount) +{ + /* No need to clear if we are already out of core. */ + if (mb->out_of_core) + return; + if (amount >= mb->len) + mb->len = 0; + else + { + mb->len -= amount; + memmove (mb->buf, mb->buf+amount, mb->len); + } +} + + +void +put_membuf (membuf_t *mb, const void *buf, size_t len) +{ + if (mb->out_of_core || !len) + return; + + if (mb->len + len >= mb->size) + { + char *p; + + mb->size += len + 1024; + p = xtryrealloc (mb->buf, mb->size); + if (!p) + { + mb->out_of_core = errno ? errno : ENOMEM; + /* Wipe out what we already accumulated. This is required + in case we are storing sensitive data here. The membuf + API does not provide another way to cleanup after an + error. */ + wipememory (mb->buf, mb->len); + return; + } + mb->buf = p; + } + if (buf) + memcpy (mb->buf + mb->len, buf, len); + else + memset (mb->buf + mb->len, 0, len); + mb->len += len; +} + + +/* A variant of put_membuf accepting a void * and returning a + gpg_error_t (which will always return 0) to be used as a generic + callback handler. This function also allows buffer to be NULL. */ +gpg_error_t +put_membuf_cb (void *opaque, const void *buf, size_t len) +{ + membuf_t *data = opaque; + + if (buf) + put_membuf (data, buf, len); + return 0; +} + + +void +put_membuf_str (membuf_t *mb, const char *string) +{ + put_membuf (mb, string, strlen (string)); +} + + +void +put_membuf_printf (membuf_t *mb, const char *format, ...) +{ + int rc; + va_list arg_ptr; + char *buf; + + va_start (arg_ptr, format); + rc = gpgrt_vasprintf (&buf, format, arg_ptr); + if (rc < 0) + mb->out_of_core = errno ? errno : ENOMEM; + va_end (arg_ptr); + if (rc >= 0) + { + put_membuf (mb, buf, strlen (buf)); + xfree (buf); + } +} + + +void * +get_membuf (membuf_t *mb, size_t *len) +{ + char *p; + + if (mb->out_of_core) + { + if (mb->buf) + { + wipememory (mb->buf, mb->len); + xfree (mb->buf); + mb->buf = NULL; + } + gpg_err_set_errno (mb->out_of_core); + return NULL; + } + + p = mb->buf; + if (len) + *len = mb->len; + mb->buf = NULL; + mb->out_of_core = ENOMEM; /* hack to make sure it won't get reused. */ + return p; +} + + +/* Same as get_membuf but shrinks the reallocated space to the + required size. */ +void * +get_membuf_shrink (membuf_t *mb, size_t *len) +{ + void *p, *pp; + size_t dummylen; + + if (!len) + len = &dummylen; + + p = get_membuf (mb, len); + if (!p) + return NULL; + if (*len) + { + pp = xtryrealloc (p, *len); + if (pp) + p = pp; + } + + return p; +} + + +/* Peek at the membuf MB. On success a pointer to the buffer is + returned which is valid until the next operation on MB. If LEN is + not NULL the current LEN of the buffer is stored there. On error + NULL is returned and ERRNO is set. */ +const void * +peek_membuf (membuf_t *mb, size_t *len) +{ + const char *p; + + if (mb->out_of_core) + { + gpg_err_set_errno (mb->out_of_core); + return NULL; + } + + p = mb->buf; + if (len) + *len = mb->len; + return p; +} |