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>
27 #define __USE_UNIX98 /* for pread() in Linux */
30 #if _FILE_OFFSET_BITS != 64
31 #error You should define _FILE_OFFSET_BITS=64
34 int exfat_open(const char* spec, int ro)
39 fd = open(spec, ro ? O_RDONLY : O_RDWR);
42 exfat_error("failed to open `%s'", spec);
45 if (fstat(fd, &stbuf) != 0)
48 exfat_error("failed to fstat `%s'", spec);
51 if (!S_ISBLK(stbuf.st_mode) && !S_ISREG(stbuf.st_mode))
54 exfat_error("`%s' is neither a block device, nor a regular file",
61 void exfat_read_raw(void* buffer, size_t size, off_t offset, int fd)
63 if (pread(fd, buffer, size, offset) != size)
64 exfat_bug("failed to read %zu bytes from file at %"PRIu64, size,
68 void exfat_write_raw(const void* buffer, size_t size, off_t offset, int fd)
70 if (pwrite(fd, buffer, size, offset) != size)
71 exfat_bug("failed to write %zu bytes to file at %"PRIu64, size,
75 ssize_t exfat_read(const struct exfat* ef, struct exfat_node* node,
76 void* buffer, size_t size, off_t offset)
80 off_t lsize, loffset, remainder;
82 if (offset >= node->size)
87 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
88 if (CLUSTER_INVALID(cluster))
90 exfat_error("got invalid cluster");
94 loffset = offset % CLUSTER_SIZE(*ef->sb);
95 remainder = MIN(size, node->size - offset);
98 if (CLUSTER_INVALID(cluster))
100 exfat_error("got invalid cluster");
103 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
104 exfat_read_raw(bufp, lsize, exfat_c2o(ef, cluster) + loffset, ef->fd);
108 cluster = exfat_next_cluster(ef, node, cluster);
110 if (!ef->ro && !ef->noatime)
111 exfat_update_atime(node);
112 return size - remainder;
115 ssize_t exfat_write(struct exfat* ef, struct exfat_node* node,
116 const void* buffer, size_t size, off_t offset)
119 const char* bufp = buffer;
120 off_t lsize, loffset, remainder;
122 if (offset + size > node->size)
124 int rc = exfat_truncate(ef, node, offset + size);
131 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
132 if (CLUSTER_INVALID(cluster))
134 exfat_error("got invalid cluster");
138 loffset = offset % CLUSTER_SIZE(*ef->sb);
140 while (remainder > 0)
142 if (CLUSTER_INVALID(cluster))
144 exfat_error("got invalid cluster");
147 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
148 exfat_write_raw(bufp, lsize, exfat_c2o(ef, cluster) + loffset, ef->fd);
152 cluster = exfat_next_cluster(ef, node, cluster);
154 exfat_update_mtime(node);
155 return size - remainder;