minix/servers/iso9660fs/read.c
2010-05-10 13:26:00 +00:00

332 lines
9.5 KiB
C

#include "inc.h"
#include <minix/com.h>
#include <minix/vfsif.h>
#include <fcntl.h>
#include "buf.h"
PRIVATE char getdents_buf[GETDENTS_BUFSIZ];
/*===========================================================================*
* fs_read *
*===========================================================================*/
PUBLIC int fs_read(void) {
int r, chunk, block_size;
int nrbytes;
cp_grant_id_t gid;
off_t position, f_size, bytes_left;
unsigned int off, cum_io;
int completed;
struct dir_record *dir;
r = OK;
/* Try to get inode according to its index */
dir = get_dir_record(fs_m_in.REQ_INODE_NR);
if (dir == NULL) return(EINVAL); /* no inode found */
position = fs_m_in.REQ_SEEK_POS_LO;
nrbytes = (unsigned) fs_m_in.REQ_NBYTES; /* number of bytes to read */
block_size = v_pri.logical_block_size_l;
gid = fs_m_in.REQ_GRANT;
f_size = dir->d_file_size;
rdwt_err = OK; /* set to EIO if disk error occurs */
cum_io = 0;
/* Split the transfer into chunks that don't span two blocks. */
while (nrbytes != 0) {
off = (unsigned int) (position % block_size);
chunk = MIN(nrbytes, block_size - off);
if (chunk < 0) chunk = block_size - off;
bytes_left = f_size - position;
if (position >= f_size) break; /* we are beyond EOF */
if (chunk > bytes_left) chunk = (int) bytes_left;
/* Read or write 'chunk' bytes. */
r = read_chunk(dir, cvul64(position), off, chunk, (unsigned) nrbytes,
gid, cum_io, block_size, &completed);
if (r != OK) break; /* EOF reached */
if (rdwt_err < 0) break;
/* Update counters and pointers. */
nrbytes -= chunk; /* bytes yet to be read */
cum_io += chunk; /* bytes read so far */
position += chunk; /* position within the file */
}
fs_m_out.RES_SEEK_POS_LO = position;
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
fs_m_out.RES_NBYTES = cum_io; /*dir->d_file_size;*/
release_dir_record(dir);
return(r);
}
/*===========================================================================*
* fs_bread *
*===========================================================================*/
PUBLIC int fs_bread(void)
{
int r, rw_flag, chunk, block_size;
cp_grant_id_t gid;
int nrbytes;
u64_t position;
unsigned int off, cum_io;
int completed;
struct dir_record *dir;
r = OK;
rw_flag = (fs_m_in.m_type == REQ_BREAD ? READING : WRITING);
gid = fs_m_in.REQ_GRANT;
position = make64(fs_m_in.REQ_SEEK_POS_LO, fs_m_in.REQ_SEEK_POS_HI);
nrbytes = (unsigned) fs_m_in.REQ_NBYTES;
block_size = v_pri.logical_block_size_l;
dir = v_pri.dir_rec_root;
if(rw_flag == WRITING) return (EIO); /* Not supported */
rdwt_err = OK; /* set to EIO if disk error occurs */
cum_io = 0;
/* Split the transfer into chunks that don't span two blocks. */
while (nrbytes != 0) {
off = rem64u(position, block_size); /* offset in blk*/
chunk = MIN(nrbytes, block_size - off);
if (chunk < 0) chunk = block_size - off;
/* Read 'chunk' bytes. */
r = read_chunk(dir, position, off, chunk, (unsigned) nrbytes,
gid, cum_io, block_size, &completed);
if (r != OK) break; /* EOF reached */
if (rdwt_err < 0) break;
/* Update counters and pointers. */
nrbytes -= chunk; /* bytes yet to be read */
cum_io += chunk; /* bytes read so far */
position= add64ul(position, chunk); /* position within the file */
}
fs_m_out.RES_SEEK_POS_LO = ex64lo(position);
fs_m_out.RES_SEEK_POS_HI = ex64hi(position);
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
fs_m_out.RES_NBYTES = cum_io;
return(r);
}
/*===========================================================================*
* fs_getdents *
*===========================================================================*/
PUBLIC int fs_getdents(void) {
struct dir_record *dir;
ino_t ino;
cp_grant_id_t gid;
size_t block_size;
off_t pos, block_pos, block, cur_pos, tmpbuf_offset, userbuf_off;
struct buf *bp;
struct dir_record *dir_tmp;
struct dirent *dirp;
int r,done,o,len,reclen;
char *cp;
char name[NAME_MAX + 1];
char name_old[NAME_MAX + 1];
/* Initialize the tmp arrays */
memset(name,'\0',NAME_MAX);
memset(name_old,'\0',NAME_MAX);
/* Get input parameters */
ino = fs_m_in.REQ_INODE_NR;
gid = fs_m_in.REQ_GRANT;
pos = fs_m_in.REQ_SEEK_POS_LO;
block_size = v_pri.logical_block_size_l;
cur_pos = pos; /* The current position */
tmpbuf_offset = 0;
userbuf_off = 0;
memset(getdents_buf, '\0', GETDENTS_BUFSIZ); /* Avoid leaking any data */
if ((dir = get_dir_record(ino)) == NULL) return(EINVAL);
block = dir->loc_extent_l; /* First block of the directory */
block += pos / block_size; /* Shift to the block where start to read */
done = FALSE;
while (cur_pos<dir->d_file_size) {
bp = get_block(block); /* Get physical block */
if (bp == NULL) {
release_dir_record(dir);
return(EINVAL);
}
block_pos = cur_pos % block_size; /* Position where to start read */
while (block_pos < block_size) {
dir_tmp = get_free_dir_record();
create_dir_record(dir_tmp,bp->b_data + block_pos,
block*block_size + block_pos);
if (dir_tmp->length == 0) { /* EOF. I exit and return 0s */
block_pos = block_size;
done = TRUE;
release_dir_record(dir_tmp);
} else { /* The dir record is valid. Copy data... */
if (dir_tmp->file_id[0] == 0) strcpy(name,".");
else if (dir_tmp->file_id[0] == 1) strcpy(name,"..");
else {
/* Extract the name from the field file_id */
strncpy(name, dir_tmp->file_id,
dir_tmp->length_file_id);
name[dir_tmp->length_file_id] = 0;
/* Tidy up file name */
cp = memchr(name, ';', NAME_MAX);
if (cp != NULL) name[cp - name] = 0;
/*If no file extension, then remove final '.'*/
if (name[strlen(name) - 1] == '.')
name[strlen(name) - 1] = '\0';
}
if (strcmp(name_old, name) == 0) {
cur_pos += dir_tmp->length;
release_dir_record(dir_tmp);
continue;
}
strcpy(name_old,name);
/* Compute the length of the name */
cp = memchr(name, '\0', NAME_MAX);
if (cp == NULL) len = NAME_MAX;
else len= cp - name;
/* Compute record length */
reclen = offsetof(struct dirent, d_name) + len + 1;
o = (reclen % sizeof(long));
if (o != 0)
reclen += sizeof(long) - o;
/* If the new record does not fit, then copy the buffer
* and start from the beginning. */
if (tmpbuf_offset + reclen > GETDENTS_BUFSIZ) {
r = sys_safecopyto(FS_PROC_NR, gid, userbuf_off,
(vir_bytes)getdents_buf, tmpbuf_offset, D);
if (r != OK)
panic("fs_getdents: sys_safecopyto failed: %d", r);
userbuf_off += tmpbuf_offset;
tmpbuf_offset= 0;
}
/* The standard data structure is created using the
* data in the buffer. */
dirp = (struct dirent *) &getdents_buf[tmpbuf_offset];
dirp->d_ino = (ino_t)(bp->b_data + block_pos);
dirp->d_off= cur_pos;
dirp->d_reclen= reclen;
memcpy(dirp->d_name, name, len);
dirp->d_name[len]= '\0';
tmpbuf_offset += reclen;
cur_pos += dir_tmp->length;
release_dir_record(dir_tmp);
}
block_pos += dir_tmp->length;
}
put_block(bp); /* release the block */
if (done == TRUE) break;
cur_pos += block_size - cur_pos;
block++; /* read the next one */
}
if (tmpbuf_offset != 0) {
r = sys_safecopyto(FS_PROC_NR, gid, userbuf_off,
(vir_bytes) getdents_buf, tmpbuf_offset, D);
if (r != OK)
panic("fs_getdents: sys_safecopyto failed: %d", r);
userbuf_off += tmpbuf_offset;
}
fs_m_out.RES_NBYTES = userbuf_off;
fs_m_out.RES_SEEK_POS_LO = cur_pos;
release_dir_record(dir); /* release the inode */
return(OK);
}
/*===========================================================================*
* read_chunk *
*===========================================================================*/
PUBLIC int read_chunk(dir, position, off, chunk, left, gid, buf_off, block_size, completed)
register struct dir_record *dir;/* pointer to inode for file to be rd/wr */
u64_t position; /* position within file to read or write */
unsigned off; /* off within the current block */
int chunk; /* number of bytes to read or write */
unsigned left; /* max number of bytes wanted after position */
cp_grant_id_t gid; /* grant */
unsigned buf_off; /* offset in grant */
int block_size; /* block size of FS operating on */
int *completed; /* number of bytes copied */
{
register struct buf *bp;
register int r = OK;
block_t b;
int file_unit, rel_block, offset;
*completed = 0;
if ((ex64lo(position) <= dir->d_file_size) &&
(ex64lo(position) > dir->data_length_l)) {
while ((dir->d_next != NULL) && (ex64lo(position) > dir->data_length_l)) {
position = sub64ul(position, dir->data_length_l);
dir = dir->d_next;
}
}
if (dir->inter_gap_size != 0) {
rel_block = div64u(position, block_size);
file_unit = rel_block / dir->data_length_l;
offset = rel_block % dir->file_unit_size;
b = dir->loc_extent_l + (dir->file_unit_size +
dir->inter_gap_size) * file_unit + offset;
} else {
b = dir->loc_extent_l + div64u(position, block_size); /* Physical position
* to read. */
}
bp = get_block(b);
/* In all cases, bp now points to a valid buffer. */
if (bp == NULL) {
panic("bp not valid in rw_chunk; this can't happen");
}
r = sys_safecopyto(FS_PROC_NR, gid, buf_off,
(vir_bytes) (bp->b_data+off), (phys_bytes) chunk, D);
put_block(bp);
return(r);
}