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/>.
21 #define _XOPEN_SOURCE 500 /* for pread() and pwrite() in Linux */
24 #include <sys/types.h>
30 #if _FILE_OFFSET_BITS != 64
31 #error You should define _FILE_OFFSET_BITS=64
39 struct exfat_dev* exfat_open(const char* spec, int ro)
41 struct exfat_dev* dev;
44 dev = malloc(sizeof(struct exfat_dev));
47 exfat_error("failed to allocate memory for device structure");
51 dev->fd = open(spec, ro ? O_RDONLY : O_RDWR);
55 exfat_error("failed to open `%s' in read-%s mode", spec,
56 ro ? "only" : "write");
59 if (fstat(dev->fd, &stbuf) != 0)
63 exfat_error("failed to fstat `%s'", spec);
66 if (!S_ISBLK(stbuf.st_mode) && !S_ISREG(stbuf.st_mode))
70 exfat_error("`%s' is neither a block device, nor a regular file",
77 int exfat_close(struct exfat_dev* dev)
79 if (close(dev->fd) != 0)
82 exfat_error("close failed");
89 int exfat_fsync(struct exfat_dev* dev)
91 if (fsync(dev->fd) != 0)
93 exfat_error("fsync failed");
99 off_t exfat_seek(struct exfat_dev* dev, off_t offset, int whence)
101 return lseek(dev->fd, offset, whence);
104 ssize_t exfat_read(struct exfat_dev* dev, void* buffer, size_t size)
106 return read(dev->fd, buffer, size);
109 ssize_t exfat_write(struct exfat_dev* dev, const void* buffer, size_t size)
111 return write(dev->fd, buffer, size);
114 void exfat_pread(struct exfat_dev* dev, void* buffer, size_t size,
117 if (pread(dev->fd, buffer, size, offset) != size)
118 exfat_bug("failed to read %zu bytes from file at %"PRIu64, size,
122 void exfat_pwrite(struct exfat_dev* dev, const void* buffer, size_t size,
125 if (pwrite(dev->fd, buffer, size, offset) != size)
126 exfat_bug("failed to write %zu bytes to file at %"PRIu64, size,
130 ssize_t exfat_generic_pread(const struct exfat* ef, struct exfat_node* node,
131 void* buffer, size_t size, off_t offset)
135 off_t lsize, loffset, remainder;
137 if (offset >= node->size)
142 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
143 if (CLUSTER_INVALID(cluster))
145 exfat_error("got invalid cluster");
149 loffset = offset % CLUSTER_SIZE(*ef->sb);
150 remainder = MIN(size, node->size - offset);
151 while (remainder > 0)
153 if (CLUSTER_INVALID(cluster))
155 exfat_error("got invalid cluster");
158 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
159 exfat_pread(ef->dev, bufp, lsize, exfat_c2o(ef, cluster) + loffset);
163 cluster = exfat_next_cluster(ef, node, cluster);
165 if (!ef->ro && !ef->noatime)
166 exfat_update_atime(node);
167 return size - remainder;
170 ssize_t exfat_generic_pwrite(struct exfat* ef, struct exfat_node* node,
171 const void* buffer, size_t size, off_t offset)
174 const char* bufp = buffer;
175 off_t lsize, loffset, remainder;
177 if (offset + size > node->size)
179 int rc = exfat_truncate(ef, node, offset + size);
186 cluster = exfat_advance_cluster(ef, node, offset / CLUSTER_SIZE(*ef->sb));
187 if (CLUSTER_INVALID(cluster))
189 exfat_error("got invalid cluster");
193 loffset = offset % CLUSTER_SIZE(*ef->sb);
195 while (remainder > 0)
197 if (CLUSTER_INVALID(cluster))
199 exfat_error("got invalid cluster");
202 lsize = MIN(CLUSTER_SIZE(*ef->sb) - loffset, remainder);
203 exfat_pwrite(ef->dev, bufp, lsize, exfat_c2o(ef, cluster) + loffset);
207 cluster = exfat_next_cluster(ef, node, cluster);
209 exfat_update_mtime(node);
210 return size - remainder;