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pbuf: pbuf_get_contiguous: allow passing NULL for buffer to prevent copying

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see bug #62832
This commit is contained in:
Simon Goldschmidt 2023-10-12 08:26:00 +02:00
parent 4f88651247
commit f5e7e8e576
1 changed files with 13 additions and 7 deletions
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20
src/core/pbuf.c
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@ -1094,12 +1094,15 @@ pbuf_copy_partial(const struct pbuf *buf, void *dataptr, u16_t len, u16_t offset
* a copy into the user-supplied buffer.
*
* @param p the pbuf from which to copy data
* @param buffer the application supplied buffer
* @param bufsize size of the application supplied buffer
* @param len length of data to copy (dataptr must be big enough). No more
* than buf->tot_len will be copied, irrespective of len
* @param buffer the application supplied buffer. May be NULL if the caller does not
* want to copy. In this case, offset + len should be checked against p->tot_len,
* since there's no way for the caller to know why NULL is returned.
* @param bufsize size of the application supplied buffer (when buffer is != NULL)
* @param len length of data to copy (p and buffer must be big enough)
* @param offset offset into the packet buffer from where to begin copying len bytes
* @return pointer to 'buffer' on success or NULL on error
* @return - pointer into pbuf payload if that is already contiguous (no copy needed)
* - pointer to 'buffer' if data was not contiguous and had to be copied
* - NULL on error
*/
void *
pbuf_get_contiguous(const struct pbuf *p, void *buffer, size_t bufsize, u16_t len, u16_t offset)
@ -1108,8 +1111,7 @@ pbuf_get_contiguous(const struct pbuf *p, void *buffer, size_t bufsize, u16_t le
u16_t out_offset;
LWIP_ERROR("pbuf_get_contiguous: invalid buf", (p != NULL), return NULL;);
LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (buffer != NULL), return NULL;);
LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (bufsize >= len), return NULL;);
LWIP_ERROR("pbuf_get_contiguous: invalid bufsize", (buffer == NULL) || (bufsize >= len), return NULL;);
q = pbuf_skip_const(p, offset, &out_offset);
if (q != NULL) {
@ -1117,6 +1119,10 @@ pbuf_get_contiguous(const struct pbuf *p, void *buffer, size_t bufsize, u16_t le
/* all data in this pbuf, return zero-copy */
return (u8_t *)q->payload + out_offset;
}
if (buffer == NULL) {
/* the caller does not want to copy */
return NULL;
}
/* need to copy */
if (pbuf_copy_partial(q, buffer, len, out_offset) != len) {
/* copying failed: pbuf is too short */