libinstaller/syslxrw.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2010 Intel Corp. - All Rights Reserved
   4  *   Copyright 2015 Paulo Alcantara <pcacjr@zytor.com>
   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, Inc., 53 Temple Place Ste 330,
   9  *   Boston MA 02111-1307, USA; either version 2 of the License, or
  10  *   (at your option) any later version; incorporated herein by reference.
  11  *
  12  * ----------------------------------------------------------------------- */
  13
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <errno.h>
  18 #include <fcntl.h>
  19 #include <unistd.h>
  20
  21 #include "syslxrw.h"
  22
  23 static void die(const char *msg)
  24 {
  25     fputs(msg, stderr);
  26     exit(1);
  27 }
  28
  29 /*
  30  * read/write wrapper functions
  31  */
  32 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
  33 {
  34     char *bufp = (char *)buf;
  35     ssize_t rv;
  36     ssize_t done = 0;
  37
  38     while (count) {
  39         rv = pread(fd, bufp, count, offset);
  40         if (rv == 0) {
  41             die("short read");
  42         } else if (rv == -1) {
  43             if (errno == EINTR) {
  44                 continue;
  45             } else {
  46                 die(strerror(errno));
  47             }
  48         } else {
  49             bufp += rv;
  50             offset += rv;
  51             done += rv;
  52             count -= rv;
  53         }
  54     }
  55
  56     return done;
  57 }
  58
  59 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
  60 {
  61     const char *bufp = (const char *)buf;
  62     ssize_t rv;
  63     ssize_t done = 0;
  64
  65     while (count) {
  66         rv = pwrite(fd, bufp, count, offset);
  67         if (rv == 0) {
  68             die("short write");
  69         } else if (rv == -1) {
  70             if (errno == EINTR) {
  71                 continue;
  72             } else {
  73                 die(strerror(errno));
  74             }
  75         } else {
  76             bufp += rv;
  77             offset += rv;
  78             done += rv;
  79             count -= rv;
  80         }
  81     }
  82
  83     return done;
  84 }