ssize_t
ih_pread(int fd, void * buf, size_t count, afs_foff_t offset)
{
afs_foff_t code;
code = OS_SEEK(fd, offset, 0);
if (code < 0)
return code;
return OS_READ(fd, buf, count);
}
/* fread for buffered I/O handles */
afs_sfsize_t
stream_read(void *ptr, afs_fsize_t size, afs_fsize_t nitems,
StreamHandle_t * streamP)
{
afs_fsize_t nbytes, bytesRead, bytesToRead;
char *p;
/* Need to seek before changing direction */
if (streamP->str_direction == STREAM_DIRECTION_NONE) {
streamP->str_direction = STREAM_DIRECTION_READ;
streamP->str_bufoff = 0;
streamP->str_buflen = 0;
} else {
assert(streamP->str_direction == STREAM_DIRECTION_READ);
}
bytesRead = 0;
nbytes = size * nitems;
p = (char *)ptr;
while (nbytes > 0 && !streamP->str_eof) {
if (streamP->str_buflen == 0) {
streamP->str_bufoff = 0;
streamP->str_buflen =
OS_READ(streamP->str_fd, streamP->str_buffer,
STREAM_HANDLE_BUFSIZE);
if (streamP->str_buflen < 0) {
streamP->str_error = errno;
streamP->str_buflen = 0;
bytesRead = 0;
break;
} else if (streamP->str_buflen == 0) {
streamP->str_eof = 1;
break;
}
}
bytesToRead = nbytes;
if (bytesToRead > streamP->str_buflen) {
bytesToRead = streamP->str_buflen;
}
memcpy(p, streamP->str_buffer + streamP->str_bufoff, bytesToRead);
p += bytesToRead;
streamP->str_bufoff += bytesToRead;
streamP->str_buflen -= bytesToRead;
bytesRead += bytesToRead;
nbytes -= bytesToRead;
}
return (bytesRead / size);
}
/**
* handle a single vol header as part of VWalkVolumeHeaders.
*
* @param[in] dp disk partition
* @param[in] volfunc function to call when a vol header is successfully read
* @param[in] name full path name to the .vol header
* @param[out] hdr header data read in from the .vol header
* @param[in] locked 1 if the partition headers are locked, 0 otherwise
* @param[in] rock the rock to pass to volfunc
*
* @return operation status
* @retval 0 success
* @retval -1 fatal error, stop scanning
* @retval 1 failed to read header
* @retval 2 volfunc callback indicated error after header read
*/
static int
_VHandleVolumeHeader(struct DiskPartition64 *dp, VWalkVolFunc volfunc,
const char *name, struct VolumeDiskHeader *hdr,
int locked, void *rock)
{
int error = 0;
FD_t fd;
if ((fd = OS_OPEN(name, O_RDONLY, 0)) == INVALID_FD
|| OS_READ(fd, hdr, sizeof(*hdr))
!= sizeof(*hdr)
|| hdr->stamp.magic != VOLUMEHEADERMAGIC) {
error = 1;
}
if (fd != INVALID_FD) {
OS_CLOSE(fd);
}
#ifdef AFSFS_DEMAND_ATTACH_FS
if (locked) {
VPartHeaderUnlock(dp);
}
#endif /* AFS_DEMAND_ATTACH_FS */
if (!error && volfunc) {
/* the volume header seems fine; call the caller-supplied
* 'we-found-a-volume-header' function */
int last = 1;
#ifdef AFS_DEMAND_ATTACH_FS
if (!locked) {
last = 0;
}
#endif /* AFS_DEMAND_ATTACH_FS */
error = (*volfunc) (dp, name, hdr, last, rock);
if (error < 0) {
return -1;
}
if (error) {
error = 2;
}
}
#ifdef AFS_DEMAND_ATTACH_FS
if (error && !locked) {
int code;
/* retry reading the volume header under the partition
* header lock, just to be safe and ensure we're not
* racing something rewriting the vol header */
code = VPartHeaderLock(dp, WRITE_LOCK);
if (code) {
Log("Error acquiring partition write lock when "
"looking at header %s\n", name);
return -1;
}
return _VHandleVolumeHeader(dp, volfunc, name, hdr, 1, rock);
}
#endif /* AFS_DEMAND_ATTACH_FS */
return error;
}
