minix/servers/iso9660fs/read.c

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/* Functions to reads_file */
#include "inc.h"
#include <minix/com.h>
#include <minix/vfsif.h>
#include <fcntl.h>
#include "buf.h"
FORWARD _PROTOTYPE( int read_chunk_s, (struct dir_record *rip, off_t position,
unsigned off, int chunk, unsigned left,cp_grant_id_t gid,
unsigned buf_off, int block_size, int *completed));
/*===========================================================================*
* fs_read_s *
*===========================================================================*/
PUBLIC int fs_read_s(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_FD_INODE_NR);
if (dir == NULL) return EINVAL; /* No inode found */
position = fs_m_in.REQ_FD_POS; /* start reading from this position */
nrbytes = (unsigned) fs_m_in.REQ_FD_NBYTES; /* number of bytes to read */
block_size = v_pri.logical_block_size_l;
gid = fs_m_in.REQ_FD_GID;
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);/* offset in blk*/
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_s(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 += chunk; /* position within the file */
}
fs_m_out.RES_FD_POS = position; /* It might change later and the VFS has
to know this value */
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
/* rip->i_update |= ATIME; */
fs_m_out.RES_FD_CUM_IO = cum_io;
fs_m_out.RES_FD_SIZE = dir->d_file_size;
release_dir_record(dir);
return(r);
}
/* Function that is called with the request read. It performs the read and
* returns the answer. */
/*===========================================================================*
* fs_read *
*===========================================================================*/
PUBLIC int fs_read(void) {
struct dir_record *dir;
int r,nrbytes,block_size, chunk, completed, seg, usr;
char* user_addr;
off_t bytes_left, position;
unsigned int off, cum_io;
r = OK;
dir = get_dir_record(fs_m_in.REQ_FD_INODE_NR);
if (dir == NULL) return EINVAL; /* No inode found */
/* Get values for reading */
position = fs_m_in.REQ_FD_POS; /* start reading from this position */
nrbytes = (unsigned) fs_m_in.REQ_FD_NBYTES; /* number of bytes to read */
user_addr = fs_m_in.REQ_FD_USER_ADDR; /* user addr buffer */
usr = fs_m_in.REQ_FD_WHO_E;
seg = fs_m_in.REQ_FD_SEG;
block_size = v_pri.logical_block_size_l;
cum_io = 0;
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;
bytes_left = dir->d_file_size - position;
if (position >= dir->d_file_size) break; /* we are beyond EOF */
if (chunk > bytes_left) chunk = (int) bytes_left;
/* Read chunk of block. */
r = read_chunk(dir, cvul64(position), off, chunk,
user_addr, seg, usr, block_size, &completed);
if (r != OK)
break; /* EOF reached */
if (rdwt_err < 0) break;
user_addr += chunk; /* user buffer address */
nrbytes -= chunk; /* bytes yet to be read */
cum_io += chunk; /* bytes read so far */
position += chunk; /* position within the file */
}
fs_m_out.RES_FD_POS = position; /* return the position now within the file */
fs_m_out.RES_FD_CUM_IO = cum_io;
fs_m_out.RES_FD_SIZE = dir->data_length_l; /* returns the size of the file */
release_dir_record(dir); /* release the dir record. */
return r;
}
/*===========================================================================*
* fs_bread_s *
*===========================================================================*/
PUBLIC int fs_bread_s(void) {
return fs_bread();
}
/*===========================================================================*
* fs_bread *
*===========================================================================*/
PUBLIC int fs_bread(void)
{
int r, usr, rw_flag, chunk, block_size, seg;
int nrbytes;
u64_t position;
unsigned int off, cum_io;
mode_t mode_word;
int completed, r2 = OK;
char *user_addr;
/* This function is called when it is requested a raw reading without any
* conversion. It is similar to fs_read but here the data is returned
* without any preprocessing. */
r = OK;
/* Get the values from the request message */
rw_flag = (fs_m_in.m_type == REQ_BREAD_S ? READING : WRITING);
usr = fs_m_in.REQ_XFD_WHO_E;
position = make64(fs_m_in.REQ_XFD_POS_LO, fs_m_in.REQ_XFD_POS_HI);
nrbytes = (unsigned) fs_m_in.REQ_XFD_NBYTES;
user_addr = fs_m_in.REQ_XFD_USER_ADDR;
seg = fs_m_in.REQ_FD_SEG;
block_size = v_pri.logical_block_size_l;
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 or write 'chunk' bytes. */
r = read_chunk(NULL, position, off, chunk,
user_addr, seg, usr, block_size, &completed);
if (r != OK) break; /* EOF reached */
if (rdwt_err < 0) break;
/* Update counters and pointers. */
user_addr += chunk; /* user buffer address */
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_XFD_POS_LO = ex64lo(position);
fs_m_out.RES_XFD_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_XFD_CUM_IO = cum_io;
return(r);
}
#define GETDENTS_BUFSIZ 257
PRIVATE char getdents_buf[GETDENTS_BUFSIZ];
/* This function returns the content of a directory using the ``standard"
* data structure (that are non FS dependent). */
/*===========================================================================*
* fs_getdents *
*===========================================================================*/
PUBLIC int fs_getdents(void) {
struct dir_record *dir;
ino_t ino;
cp_grant_id_t gid;
size_t size_to_read, 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_GDE_INODE;
gid= fs_m_in.REQ_GDE_GRANT;
size_to_read = fs_m_in.REQ_GDE_SIZE;
pos= fs_m_in.REQ_GDE_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) {
printf("I9660FS(%d) get_dir_record by fs_getdents() failed\n", SELF_E);
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 == NIL_BUF) {
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 {
/* These next functions will 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;
cp = memchr(name, ';', NAME_MAX); /* Remove the final part of the
* dir name. */
if (cp != NULL)
name[cp - name] = 0;
/* If there is no extension I remove the last '.' */
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 I copy the buffer and I 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(__FILE__,"fs_getdents: sys_safecopyto failed\n",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(__FILE__, "fs_getdents: sys_safecopyto failed\n", r);
userbuf_off += tmpbuf_offset;
}
r= ENOSYS;
fs_m_out.RES_GDE_POS_CHANGE= 0; /* No change in case of an error */
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/* r= userbuf_off;*/
fs_m_out.RES_GDE_CUM_IO = userbuf_off;
if (cur_pos >= pos)
fs_m_out.RES_GDE_POS_CHANGE= cur_pos-pos;
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else
fs_m_out.RES_GDE_POS_CHANGE= 0;
release_dir_record(dir); /* release the inode */
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r= OK;
return(r);
}
/*===========================================================================*
* fs_getdents_s *
*===========================================================================*/
PUBLIC int fs_getdents_o(void)
{
int r;
r = fs_getdents();
if(r == OK)
r = fs_m_out.RES_GDE_CUM_IO;
return(r);
}
/* Read a chunk of data that does not span in two blocks. */
PUBLIC int read_chunk(dir, position, off, chunk, buff, seg, usr, block_size,
completed)
struct dir_record *dir; /* file to read */
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 */
char *buff; /* virtual address of the user buffer */
int seg; /* T or D segment in user space */
int usr; /* which user process */
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;
b = dir->loc_extent_l + div64u(position, block_size); /* Physical position
* to read. */
bp = get_block(b); /* Get physical block */
if (bp == NIL_BUF)
return EINVAL;
r = sys_vircopy(SELF_E, D, (phys_bytes) (bp->b_data+off),
usr, seg, (phys_bytes) buff,
(phys_bytes) chunk);
if (r != OK)
panic(__FILE__,"fs_getdents: sys_vircopy failed\n",r);
put_block(bp); /* Return the block */
return OK;
}
/* Read a chunk of data that does not span in two blocks. */
/*===========================================================================*
* read_chunk_s *
*===========================================================================*/
PRIVATE int read_chunk_s(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 */
off_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 */
{
/* Read or write (part of) a block. */
register struct buf *bp;
register int r = OK;
int n;
block_t b;
dev_t dev;
int file_unit, rel_block, offset;
*completed = 0;
if ((position <= dir->d_file_size) && (position > dir->data_length_l)) {
while ((dir->d_next != NULL) && (position > dir->data_length_l)) {
position -= dir->data_length_l;
dir = dir->d_next;
}
}
if (dir->inter_gap_size != 0) {
rel_block = 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 + position / block_size; /* Physical position
* to read. */
}
bp = get_block(b);
/* In all cases, bp now points to a valid buffer. */
if (bp == NIL_BUF) {
panic(__FILE__,"bp not valid in rw_chunk, this can't happen", NO_NUM);
}
r = sys_safecopyto(FS_PROC_NR, gid, buf_off,
(vir_bytes) (bp->b_data+off), (phys_bytes) chunk, D);
put_block(bp);
return(r);
}