3 exFAT file system implementation library.
5 Copyright (C) 2009, 2010 Andrew Nayenko
7 This program is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
23 #include <sys/types.h>
25 #define __USE_UNIX98 /* for pread() in Linux */
28 #if _FILE_OFFSET_BITS != 64
29 #error You should define _FILE_OFFSET_BITS=64
32 void exfat_read_raw(void* buffer, size_t size, off_t offset, int fd)
34 if (pread(fd, buffer, size, offset) != size)
35 exfat_bug("failed to read %zu bytes from file at %"PRIu64, size,
39 void exfat_write_raw(const void* buffer, size_t size, off_t offset, int fd)
41 if (pwrite(fd, buffer, size, offset) != size)
42 exfat_bug("failed to write %zu bytes to file at %"PRIu64, size,
46 ssize_t exfat_read(const struct exfat* ef, struct exfat_node* node,
47 void* buffer, size_t size, off_t offset)
51 off_t lsize, loffset, remainder;
53 if (offset >= node->size)
58 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
59 if (CLUSTER_INVALID(cluster))
61 exfat_error("got invalid cluster");
65 loffset = offset % CLUSTER_SIZE(*ef->sb);
66 remainder = MIN(size, node->size - offset);
69 if (CLUSTER_INVALID(cluster))
71 exfat_error("got invalid cluster");
74 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
75 exfat_read_raw(bufp, lsize, exfat_c2o(ef, cluster) + loffset, ef->fd);
79 cluster = exfat_next_cluster(ef, node, cluster);
81 if (!ef->ro && !ef->noatime)
82 exfat_update_atime(node);
83 return size - remainder;
86 ssize_t exfat_write(struct exfat* ef, struct exfat_node* node,
87 const void* buffer, size_t size, off_t offset)
90 const char* bufp = buffer;
91 off_t lsize, loffset, remainder;
93 if (offset + size > node->size)
95 int rc = exfat_truncate(ef, node, offset + size);
102 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
103 if (CLUSTER_INVALID(cluster))
105 exfat_error("got invalid cluster");
109 loffset = offset % CLUSTER_SIZE(*ef->sb);
111 while (remainder > 0)
113 if (CLUSTER_INVALID(cluster))
115 exfat_error("got invalid cluster");
118 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
119 exfat_write_raw(bufp, lsize, exfat_c2o(ef, cluster) + loffset, ef->fd);
123 cluster = exfat_next_cluster(ef, node, cluster);
125 exfat_update_mtime(node);
126 return size - remainder;