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2278a69e70
This changes implementations of all iov_* functions, completing the previous step. All iov_* functions now ensure that this offset argument is within the iovec (using assertion), but lets to specify `bytes' value larger than actual length of the iovec - in this case they stops at the actual end of iovec. It is also suggested to use convinient `-1' value as `bytes' to mean just this -- "up to the end". There's one very minor semantic change here: new requiriment is that `offset' points to inside of iovec. This is checked just at the end of functions (assert()), it does not actually need to be enforced, but using any of these functions with offset pointing past the end of iovec is wrong anyway. Note: the new code in iov.c uses arithmetic with void pointers. I thought this is not supported everywhere and is a GCC extension (indeed, the C standard does not define void arithmetic). However, the original code already use void arith in iov_from_buf() function: (memcpy(..., buf + buf_off,...) which apparently works well so far (it is this way in qemu 1.0). So I left it this way and used it in other places. While at it, add a unit-test file test-iov.c, to check various corner cases with iov_from_buf(), iov_to_buf() and iov_memset(). Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
120 lines
3.2 KiB
C
120 lines
3.2 KiB
C
/*
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* Helpers for getting linearized buffers from iov / filling buffers into iovs
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*
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* Copyright IBM, Corp. 2007, 2008
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* Copyright (C) 2010 Red Hat, Inc.
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*
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* Author(s):
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* Anthony Liguori <aliguori@us.ibm.com>
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* Amit Shah <amit.shah@redhat.com>
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* Michael Tokarev <mjt@tls.msk.ru>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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* Contributions after 2012-01-13 are licensed under the terms of the
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* GNU GPL, version 2 or (at your option) any later version.
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*/
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#include "iov.h"
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size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
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size_t offset, const void *buf, size_t bytes)
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{
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size_t done;
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unsigned int i;
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for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
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if (offset < iov[i].iov_len) {
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size_t len = MIN(iov[i].iov_len - offset, bytes - done);
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memcpy(iov[i].iov_base + offset, buf + done, len);
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done += len;
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offset = 0;
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} else {
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offset -= iov[i].iov_len;
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}
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}
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assert(offset == 0);
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return done;
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}
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size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
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size_t offset, void *buf, size_t bytes)
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{
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size_t done;
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unsigned int i;
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for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
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if (offset < iov[i].iov_len) {
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size_t len = MIN(iov[i].iov_len - offset, bytes - done);
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memcpy(buf + done, iov[i].iov_base + offset, len);
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done += len;
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offset = 0;
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} else {
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offset -= iov[i].iov_len;
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}
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}
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assert(offset == 0);
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return done;
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}
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size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
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size_t offset, int fillc, size_t bytes)
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{
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size_t done;
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unsigned int i;
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for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
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if (offset < iov[i].iov_len) {
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size_t len = MIN(iov[i].iov_len - offset, bytes - done);
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memset(iov[i].iov_base + offset, fillc, len);
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done += len;
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offset = 0;
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} else {
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offset -= iov[i].iov_len;
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}
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}
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assert(offset == 0);
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return done;
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}
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size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
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{
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size_t len;
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unsigned int i;
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len = 0;
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for (i = 0; i < iov_cnt; i++) {
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len += iov[i].iov_len;
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}
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return len;
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}
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void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
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FILE *fp, const char *prefix, size_t limit)
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{
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unsigned int i, v, b;
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uint8_t *c;
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c = iov[0].iov_base;
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for (i = 0, v = 0, b = 0; b < limit; i++, b++) {
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if (i == iov[v].iov_len) {
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i = 0; v++;
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if (v == iov_cnt) {
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break;
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}
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c = iov[v].iov_base;
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}
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if ((b % 16) == 0) {
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fprintf(fp, "%s: %04x:", prefix, b);
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}
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if ((b % 4) == 0) {
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fprintf(fp, " ");
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}
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fprintf(fp, " %02x", c[i]);
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if ((b % 16) == 15) {
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fprintf(fp, "\n");
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}
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}
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if ((b % 16) != 0) {
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fprintf(fp, "\n");
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}
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}
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