iov.c

   1 /*
   2  * Helpers for getting linearized buffers from iov / filling buffers into iovs
   3  *
   4  * Copyright IBM, Corp. 2007, 2008
   5  * Copyright (C) 2010 Red Hat, Inc.
   6  *
   7  * Author(s):
   8  *  Anthony Liguori <aliguori@us.ibm.com>
   9  *  Amit Shah <amit.shah@redhat.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.  See
  12  * the COPYING file in the top-level directory.
  13  *
  14  * Contributions after 2012-01-13 are licensed under the terms of the
  15  * GNU GPL, version 2 or (at your option) any later version.
  16  */
  17
  18 #include "iov.h"
  19
  20 size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
  21                     const void *buf, size_t iov_off, size_t size)
  22 {
  23     size_t iovec_off, buf_off;
  24     unsigned int i;
  25
  26     iovec_off = 0;
  27     buf_off = 0;
  28     for (i = 0; i < iov_cnt && size; i++) {
  29         if (iov_off < (iovec_off + iov[i].iov_len)) {
  30             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off, size);
  31
  32             memcpy(iov[i].iov_base + (iov_off - iovec_off), buf + buf_off, len);
  33
  34             buf_off += len;
  35             iov_off += len;
  36             size -= len;
  37         }
  38         iovec_off += iov[i].iov_len;
  39     }
  40     return buf_off;
  41 }
  42
  43 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
  44                   void *buf, size_t iov_off, size_t size)
  45 {
  46     uint8_t *ptr;
  47     size_t iovec_off, buf_off;
  48     unsigned int i;
  49
  50     ptr = buf;
  51     iovec_off = 0;
  52     buf_off = 0;
  53     for (i = 0; i < iov_cnt && size; i++) {
  54         if (iov_off < (iovec_off + iov[i].iov_len)) {
  55             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
  56
  57             memcpy(ptr + buf_off, iov[i].iov_base + (iov_off - iovec_off), len);
  58
  59             buf_off += len;
  60             iov_off += len;
  61             size -= len;
  62         }
  63         iovec_off += iov[i].iov_len;
  64     }
  65     return buf_off;
  66 }
  67
  68 size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt,
  69                  size_t iov_off, size_t size)
  70 {
  71     size_t iovec_off, buf_off;
  72     unsigned int i;
  73
  74     iovec_off = 0;
  75     buf_off = 0;
  76     for (i = 0; i < iov_cnt && size; i++) {
  77         if (iov_off < (iovec_off + iov[i].iov_len)) {
  78             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
  79
  80             memset(iov[i].iov_base + (iov_off - iovec_off), 0, len);
  81
  82             buf_off += len;
  83             iov_off += len;
  84             size -= len;
  85         }
  86         iovec_off += iov[i].iov_len;
  87     }
  88     return buf_off;
  89 }
  90
  91 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
  92 {
  93     size_t len;
  94     unsigned int i;
  95
  96     len = 0;
  97     for (i = 0; i < iov_cnt; i++) {
  98         len += iov[i].iov_len;
  99     }
 100     return len;
 101 }
 102
 103 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
 104                  FILE *fp, const char *prefix, size_t limit)
 105 {
 106     unsigned int i, v, b;
 107     uint8_t *c;
 108
 109     c = iov[0].iov_base;
 110     for (i = 0, v = 0, b = 0; b < limit; i++, b++) {
 111         if (i == iov[v].iov_len) {
 112             i = 0; v++;
 113             if (v == iov_cnt) {
 114                 break;
 115             }
 116             c = iov[v].iov_base;
 117         }
 118         if ((b % 16) == 0) {
 119             fprintf(fp, "%s: %04x:", prefix, b);
 120         }
 121         if ((b % 4) == 0) {
 122             fprintf(fp, " ");
 123         }
 124         fprintf(fp, " %02x", c[i]);
 125         if ((b % 16) == 15) {
 126             fprintf(fp, "\n");
 127         }
 128     }
 129     if ((b % 16) != 0) {
 130         fprintf(fp, "\n");
 131     }
 132 }