snprintf/patient_write.c

   1 /*
   2  * Copyright (C) 2009  Pierre-Marc Fournier
   3  * Copyright (C) 2011  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  18  */
  19
  20 #include <stddef.h>
  21
  22 /* write() */
  23 #include <unistd.h>
  24
  25 /* writev() */
  26 #include <sys/uio.h>
  27
  28 /* send() */
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31
  32 #include <errno.h>
  33
  34 #include <share.h>
  35
  36 /*
  37  * This write is patient because it restarts if it was incomplete.
  38  */
  39
  40 ssize_t patient_write(int fd, const void *buf, size_t count)
  41 {
  42         const char *bufc = (const char *) buf;
  43         int result;
  44
  45         for(;;) {
  46                 result = write(fd, bufc, count);
  47                 if (result == -1 && errno == EINTR) {
  48                         continue;
  49                 }
  50                 if (result <= 0) {
  51                         return result;
  52                 }
  53                 count -= result;
  54                 bufc += result;
  55
  56                 if (count == 0) {
  57                         break;
  58                 }
  59         }
  60
  61         return bufc-(const char *)buf;
  62 }
  63
  64 /*
  65  * The `struct iovec *iov` is not `const` because we modify it to support
  66  * partial writes.
  67  */
  68 ssize_t patient_writev(int fd, struct iovec *iov, int iovcnt)
  69 {
  70         ssize_t written, total_written = 0;
  71         int curr_element_idx = 0;
  72
  73         for(;;) {
  74                 written = writev(fd, iov + curr_element_idx,
  75                                 iovcnt - curr_element_idx);
  76                 if (written == -1 && errno == EINTR) {
  77                         continue;
  78                 }
  79                 if (written <= 0) {
  80                         return written;
  81                 }
  82
  83                 total_written += written;
  84
  85                 /*
  86                  * If it's not the last element in the vector and we have
  87                  * written more than the current element size, then increment
  88                  * the current element index until we reach the element that
  89                  * was partially written.
  90                  */
  91                 while (curr_element_idx < iovcnt &&
  92                                 written >= iov[curr_element_idx].iov_len) {
  93                         written -= iov[curr_element_idx].iov_len;
  94                         curr_element_idx++;
  95                 }
  96
  97                 /* Maybe we are done. */
  98                 if (curr_element_idx >= iovcnt) {
  99                         break;
 100                 }
 101
 102                 /* Update the current element base and size. */
 103                 iov[curr_element_idx].iov_base += written;
 104                 iov[curr_element_idx].iov_len -= written;
 105         }
 106
 107         return total_written;
 108 }
 109
 110 ssize_t patient_send(int fd, const void *buf, size_t count, int flags)
 111 {
 112         const char *bufc = (const char *) buf;
 113         int result;
 114
 115         for(;;) {
 116                 result = send(fd, bufc, count, flags);
 117                 if (result == -1 && errno == EINTR) {
 118                         continue;
 119                 }
 120                 if (result <= 0) {
 121                         return result;
 122                 }
 123                 count -= result;
 124                 bufc += result;
 125
 126                 if (count == 0) {
 127                         break;
 128                 }
 129         }
 130
 131         return bufc - (const char *) buf;
 132 }