minix3/fs/iso9660fs/read.c

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C
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2020-02-21 00:59:27 +05:30
#include "inc.h"
#include <minix/com.h>
#include <minix/vfsif.h>
#include <minix/minlib.h>
#include <fcntl.h>
#include <stddef.h>
#include "buf.h"
static char getdents_buf[GETDENTS_BUFSIZ];
/*===========================================================================*
* fs_read *
*===========================================================================*/
int fs_read(void) {
int r, chunk, block_size;
size_t nrbytes;
cp_grant_id_t gid;
off_t position, f_size, bytes_left;
unsigned int off, cum_io;
int completed;
struct dir_record *dir;
int rw;
switch(fs_m_in.m_type) {
case REQ_READ: rw = READING; break;
case REQ_PEEK: rw = PEEKING; break;
default: panic("odd m_type");
}
r = OK;
/* Try to get inode according to its index */
dir = get_dir_record(fs_m_in.m_vfs_fs_readwrite.inode);
if (dir == NULL) return(EINVAL); /* no inode found */
position = fs_m_in.m_vfs_fs_readwrite.seek_pos;
nrbytes = fs_m_in.m_vfs_fs_readwrite.nbytes; /* number of bytes to read */
block_size = v_pri.logical_block_size_l;
gid = fs_m_in.m_vfs_fs_readwrite.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 = 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 = (int32_t) bytes_left;
/* Read or write 'chunk' bytes. */
r = read_chunk(dir, position, off, chunk,
(uint32_t) nrbytes, gid, cum_io, block_size,
&completed, rw);
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.m_fs_vfs_readwrite.seek_pos = position;
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
fs_m_out.m_fs_vfs_readwrite.nbytes = cum_io; /*dir->d_file_size;*/
release_dir_record(dir);
return(r);
}
/*===========================================================================*
* fs_bread *
*===========================================================================*/
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.m_vfs_fs_breadwrite.grant;
position = fs_m_in.m_vfs_fs_breadwrite.seek_pos;
nrbytes = fs_m_in.m_vfs_fs_breadwrite.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 = (unsigned int)(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, READING);
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.m_fs_vfs_breadwrite.seek_pos = position;
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
fs_m_out.m_fs_vfs_breadwrite.nbytes = cum_io;
return(r);
}
/*===========================================================================*
* fs_getdents *
*===========================================================================*/
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.m_vfs_fs_getdents.inode;
gid = fs_m_in.m_vfs_fs_getdents.grant;
pos = fs_m_in.m_vfs_fs_getdents.seek_pos;
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,b_data(bp) + 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)
strlcpy(name, ".", NAME_MAX + 1);
else if (dir_tmp->file_id[0] == 1)
strlcpy(name, "..", NAME_MAX + 1);
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;
}
strlcpy(name_old, name, NAME_MAX + 1);
/* 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; also does alignment. */
reclen = _DIRENT_RECLEN(dirp, len);
/* 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(VFS_PROC_NR, gid, userbuf_off,
(vir_bytes)getdents_buf, tmpbuf_offset);
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_fileno = (u32_t)(b_data(bp) + (size_t)block_pos);
dirp->d_reclen= reclen;
dirp->d_type = fs_mode_to_type(dir_tmp->d_mode);
dirp->d_namlen = len;
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(VFS_PROC_NR, gid, userbuf_off,
(vir_bytes) getdents_buf, tmpbuf_offset);
if (r != OK)
panic("fs_getdents: sys_safecopyto failed: %d", r);
userbuf_off += tmpbuf_offset;
}
fs_m_out.m_fs_vfs_getdents.nbytes = userbuf_off;
fs_m_out.m_fs_vfs_getdents.seek_pos = cur_pos;
release_dir_record(dir); /* release the inode */
return(OK);
}
/*===========================================================================*
* read_chunk *
*===========================================================================*/
int read_chunk(dir, position, off, chunk, left, gid, buf_off, block_size, completed, rw)
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 */
int rw; /* READING or PEEKING */
{
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 -= dir->data_length_l;
dir = dir->d_next;
}
}
if (dir->inter_gap_size != 0) {
rel_block = (unsigned long)(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 + (unsigned long)(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");
}
if(rw == READING) {
r = sys_safecopyto(VFS_PROC_NR, gid, buf_off,
(vir_bytes) (b_data(bp)+off), (phys_bytes) chunk);
}
put_block(bp);
return(r);
}