src/buffer.c

   1 /*
   2  * Copyright (C) 2013-2014 Intel Corporation.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  17  *
  18  * Authors:
  19  *       José Bollo <jose.bollo@open.eurogiciel.org>
  20  *       Stéphane Desneux <stephane.desneux@open.eurogiciel.org>
  21  *       Jean-Benoit Martin <jean-benoit.martin@open.eurogiciel.org>
  22  *
  23  */
  24
  25 #define _GNU_SOURCE
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <stdlib.h>
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <errno.h>
  35 #include <sys/mman.h>
  36 #include <sys/stat.h>
  37
  38 #include "buffer.h"
  39
  40 static int buffread(struct buffer *buffer, int fd)
  41 {
  42         const int size = 4096;
  43         void *p;
  44         char *memory = NULL;
  45         size_t length = 0;
  46         ssize_t status;
  47
  48         /* do read */
  49         for (;;) {
  50                 p = realloc(memory, length + size);
  51                 if (p == NULL) {
  52                         free(memory);
  53                         return -1;
  54                 }
  55                 memory = p;
  56                 status = read(fd, memory+length, size);
  57                 if (status == 0) {
  58                         buffer->buffer = memory;
  59                         buffer->length = length;
  60                         buffer->mapped = 0;
  61                         return 0;
  62                 }
  63                 if (status > 0) {
  64                         length = length + (int)status;
  65                 } else if (errno != EAGAIN && errno != EINTR) {
  66                         free(memory);
  67                         return -1;
  68                 }
  69         }
  70 }
  71
  72 int buffer_create(struct buffer *buffer, const char *pathname)
  73 {
  74         int fd, result;
  75         struct stat bstat;
  76         void *memory;
  77         size_t length;
  78
  79         result = open(pathname, O_RDONLY);
  80         if (result >= 0) {
  81                 fd = result;
  82                 result = fstat(fd, &bstat);
  83                 if (result == 0) {
  84                         length = (size_t)bstat.st_size;
  85                         if (bstat.st_size != (off_t)length) {
  86                                 errno = EOVERFLOW;
  87                                 result = -1;
  88                         } else {
  89                                 memory = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
  90                                 if (memory != MAP_FAILED) {
  91                                         buffer->buffer = memory;
  92                                         buffer->length = length;
  93                                         buffer->mapped = 1;
  94                                 } else {
  95                                         result = buffread(buffer, fd);
  96                                 }
  97                         }
  98                 }
  99                 close(fd);
 100         }
 101         return result;
 102 }
 103
 104 int buffer_destroy(struct buffer *buffer)
 105 {
 106         if (buffer->mapped)
 107                 return munmap(buffer->buffer, buffer->length);
 108         free(buffer->buffer);
 109         return 0;
 110 }
 111