40 #include <sys/strsubr.h>

    42 #include <sys/sysmacros.h>

   248 

   249 /* Copy userdata into a new mblk_t */

   250 mblk_t *

   251 mcopyinuio(struct stdata *stp, uio_t *uiop, ssize_t iosize,

   252     ssize_t maxblk, int *errorp)

   253 {

   254 	mblk_t	*head = NULL, **tail = &head;

   255 	size_t	offset = stp->sd_wroff;

   256 

   257 	if (iosize == INFPSZ || iosize > uiop->uio_resid)

   258 		iosize = uiop->uio_resid;

   259 

   260 	if (maxblk == INFPSZ)

   261 		maxblk = iosize;

   262 

   263 	/* Nothing to do in these cases, so we're done */

   264 	if (iosize < 0 || maxblk < 0 || (maxblk == 0 && iosize > 0))

   265 		goto done;

   266 

   267 	if (stp->sd_flag & STRCOPYCACHED)

   268 		uiop->uio_extflg |= UIO_COPY_CACHED;

   269 

   270 	/*

   271 	 * We will enter the loop below if iosize is 0; it will allocate an

   272 	 * empty message block and call uiomove(9F) which will just return.

   273 	 * We could avoid that with an extra check but would only slow

   274 	 * down the much more likely case where iosize is larger than 0.

   275 	 */

   276 	do {

   277 		ssize_t blocksize;

   278 		mblk_t  *mp;

   279 

   280 		blocksize = MIN(iosize, maxblk);

   281 		ASSERT(blocksize >= 0);

   282 		if ((mp = allocb_cred(offset + blocksize, CRED())) == NULL) {

   283 			*errorp = ENOMEM;

   284 			return (head);

   285 		}

   286 		mp->b_rptr += offset;

   287 		mp->b_wptr = mp->b_rptr + blocksize;

   288 		DB_CPID(mp) = curproc->p_pid;

   289 

   290 		*tail = mp;

   291 		tail = &mp->b_cont;

   292 

   293 		/* uiomove(9F) either returns 0 or EFAULT */

   294 		if ((*errorp = uiomove(mp->b_rptr, (size_t)blocksize,

   295 		    UIO_WRITE, uiop)) != 0) {

   296 			ASSERT(*errorp != ENOMEM);

   297 			freemsg(head);

   298 			return (NULL);

   299 		}

   300 

   301 		iosize -= blocksize;

   302 	} while (iosize > 0);

   303 

   304 done:

   305 	*errorp = 0;

   306 	return (head);

   307 }