lib/util/iov_buf.h

   1 /*
   2  * Unix SMB/CIFS implementation.
   3  * Samba system utilities
   4  * Copyright (C) Volker Lendecke 2014
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #ifndef __LIB_IOV_BUF_H__
  21 #define __LIB_IOV_BUF_H__
  22
  23 #include "replace.h"
  24 #include <talloc.h>
  25 #include "system/filesys.h"
  26
  27 static inline
  28 ssize_t iov_buf(const struct iovec *iov, int iovcnt,
  29                 uint8_t *buf, size_t buflen)
  30 {
  31         size_t needed = 0;
  32         uint8_t *p = buf;
  33         int i;
  34
  35         for (i=0; i<iovcnt; i++) {
  36                 size_t thislen = iov[i].iov_len;
  37                 size_t tmp;
  38
  39                 tmp = needed + thislen;
  40
  41                 if (tmp < needed) {
  42                         /* wrap */
  43                         return -1;
  44                 }
  45                 needed = tmp;
  46
  47                 if ((p != NULL) && needed <= buflen && thislen > 0) {
  48                         memcpy(p, iov[i].iov_base, thislen);
  49                         p += thislen;
  50                 }
  51         }
  52
  53         return needed;
  54 }
  55
  56 static inline
  57 ssize_t iov_buflen(const struct iovec *iov, int iovcnt)
  58 {
  59         return iov_buf(iov, iovcnt, NULL, 0);
  60 }
  61
  62 static inline
  63 bool iov_advance(struct iovec **iov, int *iovcnt, size_t n)
  64 {
  65         struct iovec *v = *iov;
  66         int cnt = *iovcnt;
  67
  68         while (n > 0) {
  69                 if (cnt == 0) {
  70                         return false;
  71                 }
  72                 if (n < v->iov_len) {
  73                         v->iov_base = (char *)v->iov_base + n;
  74                         v->iov_len -= n;
  75                         break;
  76                 }
  77                 n -= v->iov_len;
  78                 v += 1;
  79                 cnt -= 1;
  80         }
  81
  82         /*
  83          * Skip 0-length iovec's
  84          *
  85          * There might be empty buffers at the end of iov. Next time we do a
  86          * readv/writev based on this iov would give 0 transferred bytes, also
  87          * known as EPIPE. So we need to be careful discarding them.
  88          */
  89
  90         while ((cnt > 0) && (v->iov_len == 0)) {
  91                 v += 1;
  92                 cnt -= 1;
  93         }
  94
  95         *iov = v;
  96         *iovcnt = cnt;
  97         return true;
  98 }
  99
 100 uint8_t *iov_concat(TALLOC_CTX *mem_ctx, const struct iovec *iov, int count);
 101
 102 #endif