/*
write out disk_block
*/
void AP_Terrain::write_block(void)
{
seek_offset();
if (io_failure) {
return;
}
disk_block.block.crc = get_block_crc(disk_block.block);
ssize_t ret = ::write(fd, &disk_block, sizeof(disk_block));
if (ret != sizeof(disk_block)) {
#if TERRAIN_DEBUG
hal.console->printf("write failed - %s\n", strerror(errno));
#endif
::close(fd);
fd = -1;
io_failure = true;
} else {
::fsync(fd);
#if TERRAIN_DEBUG
printf("wrote block at %ld %ld ret=%d mask=%07llx\n",
(long)disk_block.block.lat,
(long)disk_block.block.lon,
(int)ret,
(unsigned long long)disk_block.block.bitmap);
#endif
}
disk_io_state = DiskIoDoneWrite;
}
/*
read in disk_block
*/
void AP_Terrain::read_block(void)
{
seek_offset();
if (io_failure) {
return;
}
int32_t lat = disk_block.block.lat;
int32_t lon = disk_block.block.lon;
ssize_t ret = ::read(fd, &disk_block, sizeof(disk_block));
if (ret != sizeof(disk_block) ||
disk_block.block.lat != lat ||
disk_block.block.lon != lon ||
disk_block.block.bitmap == 0 ||
disk_block.block.spacing != grid_spacing ||
disk_block.block.version != TERRAIN_GRID_FORMAT_VERSION ||
disk_block.block.crc != get_block_crc(disk_block.block)) {
#if TERRAIN_DEBUG
printf("read empty block at %ld %ld ret=%d\n",
(long)lat,
(long)lon,
(int)ret);
#endif
// a short read or bad data is not an IO failure, just a
// missing block on disk
memset(&disk_block, 0, sizeof(disk_block));
disk_block.block.lat = lat;
disk_block.block.lon = lon;
disk_block.block.bitmap = 0;
} else {
#if TERRAIN_DEBUG
printf("read block at %ld %ld ret=%d mask=%07llx\n",
(long)lat,
(long)lon,
(int)ret,
(unsigned long long)disk_block.block.bitmap);
#endif
}
disk_io_state = DiskIoDoneRead;
}
/*
* Position input/output data streams before starting the copy. Device type
* dependent. Seekable devices use lseek, and the rest position by reading.
* Seeking past the end of file can cause null blocks to be written to the
* output.
*/
void
pos_in(void)
{
off_t cnt;
int warned;
ssize_t nr;
size_t bcnt;
/* If known to be seekable, try to seek on it. */
if (in.flags & ISSEEK) {
errno = 0;
if (lseek(in.fd, seek_offset(&in), SEEK_CUR) == -1 &&
errno != 0)
err(1, "%s", in.name);
return;
}
/* Don't try to read a really weird amount (like negative). */
if (in.offset < 0)
errx(1, "%s: illegal offset", "iseek/skip");
/*
* Read the data. If a pipe, read until satisfy the number of bytes
* being skipped. No differentiation for reading complete and partial
* blocks for other devices.
*/
for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
if ((nr = read(in.fd, in.db, bcnt)) > 0) {
if (in.flags & ISPIPE) {
if (!(bcnt -= nr)) {
bcnt = in.dbsz;
--cnt;
}
} else
--cnt;
if (need_summary)
summary();
continue;
}
if (nr == 0) {
if (files_cnt > 1) {
--files_cnt;
continue;
}
errx(1, "skip reached end of input");
}
/*
* Input error -- either EOF with no more files, or I/O error.
* If noerror not set die. POSIX requires that the warning
* message be followed by an I/O display.
*/
if (ddflags & C_NOERROR) {
if (!warned) {
warn("%s", in.name);
warned = 1;
summary();
}
continue;
}
err(1, "%s", in.name);
}
}
void
pos_out(void)
{
struct mtop t_op;
off_t cnt;
ssize_t n;
/*
* If not a tape, try seeking on the file. Seeking on a pipe is
* going to fail, but don't protect the user -- they shouldn't
* have specified the seek operand.
*/
if (out.flags & (ISSEEK | ISPIPE)) {
errno = 0;
if (lseek(out.fd, seek_offset(&out), SEEK_CUR) == -1 &&
errno != 0)
err(1, "%s", out.name);
return;
}
/* Don't try to read a really weird amount (like negative). */
if (out.offset < 0)
errx(1, "%s: illegal offset", "oseek/seek");
/* If no read access, try using mtio. */
if (out.flags & NOREAD) {
t_op.mt_op = MTFSR;
t_op.mt_count = out.offset;
if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
err(1, "%s", out.name);
return;
}
/* Read it. */
for (cnt = 0; cnt < out.offset; ++cnt) {
if ((n = read(out.fd, out.db, out.dbsz)) > 0)
continue;
if (n == -1)
err(1, "%s", out.name);
/*
* If reach EOF, fill with NUL characters; first, back up over
* the EOF mark. Note, cnt has not yet been incremented, so
* the EOF read does not count as a seek'd block.
*/
t_op.mt_op = MTBSR;
t_op.mt_count = 1;
if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
err(1, "%s", out.name);
while (cnt++ < out.offset) {
n = write(out.fd, out.db, out.dbsz);
if (n == -1)
err(1, "%s", out.name);
if ((size_t)n != out.dbsz)
errx(1, "%s: write failure", out.name);
}
break;
}
}