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wpabuf: Get rid of separate ext_data pointer 

Use an explicit pointer to the beginning of the buffer and a flag
to indicate whether that is to external data or not. This avoids
a branch whenever accessing the buffer and helps some static
analyzers to understand the wpabuf memory uses better.

Signed-hostap: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2012-08-19 18:25:25 +03:00
parent 392824ef10
commit 1871f7116e
2 changed files with 22 additions and 17 deletions
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19
src/utils/wpabuf.c
View File

@ -1,6 +1,6 @@
/*
* Dynamic data buffer
* Copyright (c) 2007-2009, Jouni Malinen <j@w1.fi>
* Copyright (c) 2007-2012, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -68,12 +68,12 @@ int wpabuf_resize(struct wpabuf **_buf, size_t add_len)
if (buf->used + add_len > buf->size) {
unsigned char *nbuf;
if (buf->ext_data) {
nbuf = os_realloc(buf->ext_data, buf->used + add_len);
if (buf->flags & WPABUF_FLAG_EXT_DATA) {
nbuf = os_realloc(buf->buf, buf->used + add_len);
if (nbuf == NULL)
return -1;
os_memset(nbuf + buf->used, 0, add_len);
buf->ext_data = nbuf;
buf->buf = nbuf;
} else {
#ifdef WPA_TRACE
nbuf = os_realloc(trace, sizeof(struct wpabuf_trace) +
@ -95,6 +95,7 @@ int wpabuf_resize(struct wpabuf **_buf, size_t add_len)
os_memset(nbuf + sizeof(struct wpabuf) + buf->used, 0,
add_len);
#endif /* WPA_TRACE */
buf->buf = (u8 *) (buf + 1);
*_buf = buf;
}
buf->size = buf->used + add_len;
@ -126,6 +127,7 @@ struct wpabuf * wpabuf_alloc(size_t len)
#endif /* WPA_TRACE */
buf->size = len;
buf->buf = (u8 *) (buf + 1);
return buf;
}
@ -148,7 +150,8 @@ struct wpabuf * wpabuf_alloc_ext_data(u8 *data, size_t len)
buf->size = len;
buf->used = len;
buf->ext_data = data;
buf->buf = data;
buf->flags |= WPABUF_FLAG_EXT_DATA;
return buf;
}
@ -189,12 +192,14 @@ void wpabuf_free(struct wpabuf *buf)
wpa_trace_show("wpabuf_free magic mismatch");
abort();
}
os_free(buf->ext_data);
if (buf->flags & WPABUF_FLAG_EXT_DATA)
os_free(buf->buf);
os_free(trace);
#else /* WPA_TRACE */
if (buf == NULL)
return;
os_free(buf->ext_data);
if (buf->flags & WPABUF_FLAG_EXT_DATA)
os_free(buf->buf);
os_free(buf);
#endif /* WPA_TRACE */
}

20
src/utils/wpabuf.h
View File

@ -1,6 +1,6 @@
/*
* Dynamic data buffer
* Copyright (c) 2007-2009, Jouni Malinen <j@w1.fi>
* Copyright (c) 2007-2012, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -9,6 +9,9 @@
#ifndef WPABUF_H
#define WPABUF_H
/* wpabuf::buf is a pointer to external data */
#define WPABUF_FLAG_EXT_DATA BIT(0)
/*
* Internal data structure for wpabuf. Please do not touch this directly from
* elsewhere. This is only defined in header file to allow inline functions
@ -17,8 +20,8 @@
struct wpabuf {
size_t size; /* total size of the allocated buffer */
size_t used; /* length of data in the buffer */
u8 *ext_data; /* pointer to external data; NULL if data follows
* struct wpabuf */
u8 *buf; /* pointer to the head of the buffer */
unsigned int flags;
/* optionally followed by the allocated buffer */
};
@ -72,9 +75,7 @@ static inline size_t wpabuf_tailroom(const struct wpabuf *buf)
*/
static inline const void * wpabuf_head(const struct wpabuf *buf)
{
if (buf->ext_data)
return buf->ext_data;
return buf + 1;
return buf->buf;
}
static inline const u8 * wpabuf_head_u8(const struct wpabuf *buf)
@ -89,9 +90,7 @@ static inline const u8 * wpabuf_head_u8(const struct wpabuf *buf)
*/
static inline void * wpabuf_mhead(struct wpabuf *buf)
{
if (buf->ext_data)
return buf->ext_data;
return buf + 1;
return buf->buf;
}
static inline u8 * wpabuf_mhead_u8(struct wpabuf *buf)
@ -150,7 +149,8 @@ static inline void wpabuf_put_buf(struct wpabuf *dst,
static inline void wpabuf_set(struct wpabuf *buf, const void *data, size_t len)
{
buf->ext_data = (u8 *) data;
buf->buf = (u8 *) data;
buf->flags = WPABUF_FLAG_EXT_DATA;
buf->size = buf->used = len;
}