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minix/servers/ext2/read.c
Thomas Veerman c1a31d53d9 stat.h: remove some big_ types 
Change-Id: I84017db3d54edfb823cc52e02d0b07fccb003988
2014-02-18 11:25:01 +01:00

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/* Created (MFS based):
* February 2010 (Evgeniy Ivanov)
*/
#include "fs.h"
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <minix/com.h>
#include <minix/u64.h>
#include "buf.h"
#include "inode.h"
#include "super.h"
#include <minix/vfsif.h>
#include <sys/param.h>
#include <assert.h>
#include <sys/param.h>
static struct buf *rahead(struct inode *rip, block_t baseblock, u64_t
position, unsigned bytes_ahead);
static int rw_chunk(struct inode *rip, u64_t position, unsigned off,
size_t chunk, unsigned left, int rw_flag, cp_grant_id_t gid, unsigned
buf_off, unsigned int block_size, int *completed);
static off_t rdahedpos; /* position to read ahead */
static struct inode *rdahed_inode; /* pointer to inode to read ahead */
/*===========================================================================*
* fs_readwrite *
*===========================================================================*/
int fs_readwrite(void)
{
int r, rw_flag, block_spec;
int regular;
cp_grant_id_t gid;
off_t position, f_size, bytes_left;
unsigned int off, cum_io, block_size, chunk;
pmode_t mode_word;
int completed;
struct inode *rip;
size_t nrbytes;
r = OK;
/* Find the inode referred */
if ((rip = find_inode(fs_dev, (pino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(EINVAL);
mode_word = rip->i_mode & I_TYPE;
regular = (mode_word == I_REGULAR || mode_word == I_NAMED_PIPE);
block_spec = (mode_word == I_BLOCK_SPECIAL ? 1 : 0);
/* Determine blocksize */
if (block_spec) {
block_size = get_block_size( (dev_t) rip->i_block[0]);
f_size = MAX_FILE_POS;
} else {
block_size = rip->i_sp->s_block_size;
f_size = rip->i_size;
if (f_size < 0) f_size = MAX_FILE_POS;
}
rw_flag = (fs_m_in.m_type == REQ_READ ? READING : WRITING);
switch(fs_m_in.m_type) {
case REQ_READ: rw_flag = READING; break;
case REQ_WRITE: rw_flag = WRITING; break;
case REQ_PEEK: rw_flag = PEEKING; break;
default: panic("odd request");
}
gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
position = (off_t) fs_m_in.REQ_SEEK_POS_LO;
nrbytes = (size_t) fs_m_in.REQ_NBYTES;
rdwt_err = OK; /* set to EIO if disk error occurs */
if (rw_flag == WRITING && !block_spec) {
/* Check in advance to see if file will grow too big. */
if (position > (off_t) (rip->i_sp->s_max_size - nrbytes))
return(EFBIG);
}
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 (rw_flag == READING) {
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 = rw_chunk(rip, ((u64_t)((unsigned long)position)), off, chunk,
nrbytes, rw_flag, 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 += (off_t) chunk; /* position within the file */
}
fs_m_out.RES_SEEK_POS_LO = position; /* It might change later and the VFS
has to know this value */
/* On write, update file size and access time. */
if (rw_flag == WRITING) {
if (regular || mode_word == I_DIRECTORY) {
if (position > f_size) rip->i_size = position;
}
}
/* Check to see if read-ahead is called for, and if so, set it up. */
if(rw_flag == READING && rip->i_seek == NO_SEEK &&
(unsigned int) position % block_size == 0 &&
(regular || mode_word == I_DIRECTORY)) {
rdahed_inode = rip;
rdahedpos = position;
}
rip->i_seek = NO_SEEK;
if (rdwt_err != OK) r = rdwt_err; /* check for disk error */
if (rdwt_err == END_OF_FILE) r = OK;
if (r == OK) {
if (rw_flag == READING) rip->i_update |= ATIME;
if (rw_flag == WRITING) rip->i_update |= CTIME | MTIME;
rip->i_dirt = IN_DIRTY; /* inode is thus now dirty */
}
fs_m_out.RES_NBYTES = cum_io;
return(r);
}
/*===========================================================================*
* fs_breadwrite *
*===========================================================================*/
int fs_breadwrite(void)
{
int r, rw_flag, completed;
cp_grant_id_t gid;
u64_t position;
unsigned int off, cum_io, chunk, block_size;
size_t nrbytes;
/* Pseudo inode for rw_chunk */
struct inode rip;
r = OK;
/* Get the values from the request message */
rw_flag = (fs_m_in.m_type == REQ_BREAD ? READING : WRITING);
gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
position = make64((unsigned long) fs_m_in.REQ_SEEK_POS_LO,
(unsigned long) fs_m_in.REQ_SEEK_POS_HI);
nrbytes = (size_t) fs_m_in.REQ_NBYTES;
block_size = get_block_size( (dev_t) fs_m_in.REQ_DEV2);
rip.i_block[0] = (block_t) fs_m_in.REQ_DEV2;
rip.i_mode = I_BLOCK_SPECIAL;
rip.i_size = 0;
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);
/* Read or write 'chunk' bytes. */
r = rw_chunk(&rip, position, off, chunk, nrbytes, rw_flag, 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 = 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);
}
/*===========================================================================*
* rw_chunk *
*===========================================================================*/
static int rw_chunk(rip, position, off, chunk, left, rw_flag, gid,
buf_off, block_size, completed)
register struct inode *rip; /* 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 */
unsigned int chunk; /* number of bytes to read or write */
unsigned left; /* max number of bytes wanted after position */
int rw_flag; /* READING, WRITING or PEEKING */
cp_grant_id_t gid; /* grant */
unsigned buf_off; /* offset in grant */
unsigned 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 = NULL;
register int r = OK;
int n, block_spec;
block_t b;
dev_t dev;
ino_t ino = VMC_NO_INODE;
u64_t ino_off = rounddown(position, block_size);
/* rw_flag:
* READING: read from FS, copy to user
* WRITING: copy from user, write to FS
* PEEKING: try to get all the blocks into the cache, no copying
*/
*completed = 0;
block_spec = (rip->i_mode & I_TYPE) == I_BLOCK_SPECIAL;
if (block_spec) {
b = div64u(position, block_size);
dev = (dev_t) rip->i_block[0];
} else {
if (ex64hi(position) != 0)
panic("rw_chunk: position too high");
b = read_map(rip, (off_t) ex64lo(position), 0);
dev = rip->i_dev;
ino = rip->i_num;
assert(ino != VMC_NO_INODE);
}
if (!block_spec && b == NO_BLOCK) {
if (rw_flag == READING) {
/* Reading from a nonexistent block. Must read as all zeros.*/
r = sys_safememset(VFS_PROC_NR, gid, (vir_bytes) buf_off,
0, (size_t) chunk);
if(r != OK) {
printf("ext2fs: sys_safememset failed\n");
}
return r;
} else {
/* Writing to or peeking a nonexistent block.
* Create and enter in inode.
*/
if ((bp = new_block(rip, (off_t) ex64lo(position))) == NULL)
return(err_code);
}
} else if (rw_flag == READING || rw_flag == PEEKING) {
/* Read and read ahead if convenient. */
bp = rahead(rip, b, position, left);
} else {
/* Normally an existing block to be partially overwritten is first read
* in. However, a full block need not be read in. If it is already in
* the cache, acquire it, otherwise just acquire a free buffer.
*/
n = (chunk == block_size ? NO_READ : NORMAL);
if (!block_spec && off == 0 && (off_t) ex64lo(position) >= rip->i_size)
n = NO_READ;
if(block_spec) {
assert(ino == VMC_NO_INODE);
bp = get_block(dev, b, n);
} else {
assert(ino != VMC_NO_INODE);
assert(!(ino_off % block_size));
bp = lmfs_get_block_ino(dev, b, n, ino, ino_off);
}
}
/* 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_flag == WRITING && chunk != block_size && !block_spec &&
(off_t) ex64lo(position) >= rip->i_size && off == 0) {
zero_block(bp);
}
if (rw_flag == READING) {
/* Copy a chunk from the block buffer to user space. */
r = sys_safecopyto(VFS_PROC_NR, gid, (vir_bytes) buf_off,
(vir_bytes) (b_data(bp)+off), (size_t) chunk);
} else if(rw_flag == WRITING) {
/* Copy a chunk from user space to the block buffer. */
r = sys_safecopyfrom(VFS_PROC_NR, gid, (vir_bytes) buf_off,
(vir_bytes) (b_data(bp)+off), (size_t) chunk);
lmfs_markdirty(bp);
}
n = (off + chunk == block_size ? FULL_DATA_BLOCK : PARTIAL_DATA_BLOCK);
put_block(bp, n);
return(r);
}
/*===========================================================================*
* read_map *
*===========================================================================*/
block_t read_map(rip, position, opportunistic)
register struct inode *rip; /* ptr to inode to map from */
off_t position; /* position in file whose blk wanted */
int opportunistic;
{
/* Given an inode and a position within the corresponding file, locate the
* block number in which that position is to be found and return it.
*/
struct buf *bp;
int mindex;
block_t b;
unsigned long excess, block_pos;
static char first_time = TRUE;
static long addr_in_block;
static long addr_in_block2;
static long doub_ind_s;
static long triple_ind_s;
static long out_range_s;
int iomode = NORMAL;
if(opportunistic) iomode = PREFETCH;
if (first_time) {
addr_in_block = rip->i_sp->s_block_size / BLOCK_ADDRESS_BYTES;
addr_in_block2 = addr_in_block * addr_in_block;
doub_ind_s = EXT2_NDIR_BLOCKS + addr_in_block;
triple_ind_s = doub_ind_s + addr_in_block2;
out_range_s = triple_ind_s + addr_in_block2 * addr_in_block;
first_time = FALSE;
}
block_pos = position / rip->i_sp->s_block_size; /* relative blk # in file */
/* Is 'position' to be found in the inode itself? */
if (block_pos < EXT2_NDIR_BLOCKS)
return(rip->i_block[block_pos]);
/* It is not in the inode, so it must be single, double or triple indirect */
if (block_pos < doub_ind_s) {
b = rip->i_block[EXT2_NDIR_BLOCKS]; /* address of single indirect block */
mindex = block_pos - EXT2_NDIR_BLOCKS;
} else if (block_pos >= out_range_s) { /* TODO: do we need it? */
return(NO_BLOCK);
} else {
/* double or triple indirect block. At first if it's triple,
* find double indirect block.
*/
excess = block_pos - doub_ind_s;
b = rip->i_block[EXT2_DIND_BLOCK];
if (block_pos >= triple_ind_s) {
b = rip->i_block[EXT2_TIND_BLOCK];
if (b == NO_BLOCK) return(NO_BLOCK);
bp = get_block(rip->i_dev, b, NORMAL); /* get triple ind block */
ASSERT(lmfs_dev(bp) != NO_DEV);
ASSERT(lmfs_dev(bp) == rip->i_dev);
excess = block_pos - triple_ind_s;
mindex = excess / addr_in_block2;
b = rd_indir(bp, mindex); /* num of double ind block */
put_block(bp, INDIRECT_BLOCK); /* release triple ind block */
excess = excess % addr_in_block2;
}
if (b == NO_BLOCK) return(NO_BLOCK);
bp = get_block(rip->i_dev, b, iomode); /* get double indirect block */
if(opportunistic && lmfs_dev(bp) == NO_DEV) {
put_block(bp, INDIRECT_BLOCK);
return NO_BLOCK;
}
ASSERT(lmfs_dev(bp) != NO_DEV);
ASSERT(lmfs_dev(bp) == rip->i_dev);
mindex = excess / addr_in_block;
b = rd_indir(bp, mindex); /* num of single ind block */
put_block(bp, INDIRECT_BLOCK); /* release double ind block */
mindex = excess % addr_in_block; /* index into single ind blk */
}
if (b == NO_BLOCK) return(NO_BLOCK);
bp = get_block(rip->i_dev, b, iomode); /* get single indirect block */
if(opportunistic && lmfs_dev(bp) == NO_DEV) {
put_block(bp, INDIRECT_BLOCK);
return NO_BLOCK;
}
ASSERT(lmfs_dev(bp) != NO_DEV);
ASSERT(lmfs_dev(bp) == rip->i_dev);
b = rd_indir(bp, mindex);
put_block(bp, INDIRECT_BLOCK); /* release single ind block */
return(b);
}
struct buf *get_block_map(register struct inode *rip, u64_t position)
{
block_t b = read_map(rip, position, 0); /* get block number */
int block_size = get_block_size(rip->i_dev);
if(b == NO_BLOCK)
return NULL;
position = rounddown(position, block_size);
assert(rip->i_num != VMC_NO_INODE);
return lmfs_get_block_ino(rip->i_dev, b, NORMAL, rip->i_num, position);
}
/*===========================================================================*
* rd_indir *
*===========================================================================*/
block_t rd_indir(bp, mindex)
struct buf *bp; /* pointer to indirect block */
int mindex; /* index into *bp */
{
if (bp == NULL)
panic("rd_indir() on NULL");
/* TODO: use conv call */
return conv4(le_CPU, b_ind(bp)[mindex]);
}
/*===========================================================================*
* read_ahead *
*===========================================================================*/
void read_ahead()
{
/* Read a block into the cache before it is needed. */
unsigned int block_size;
register struct inode *rip;
struct buf *bp;
block_t b;
if(!rdahed_inode)
return;
rip = rdahed_inode; /* pointer to inode to read ahead from */
block_size = get_block_size(rip->i_dev);
rdahed_inode = NULL; /* turn off read ahead */
if ( (b = read_map(rip, rdahedpos, 1)) == NO_BLOCK) return; /* at EOF */
assert(rdahedpos >= 0); /* So we can safely cast it to unsigned below */
bp = rahead(rip, b, ((u64_t)((unsigned long)rdahedpos)), block_size);
put_block(bp, PARTIAL_DATA_BLOCK);
}
/*===========================================================================*
* rahead *
*===========================================================================*/
static struct buf *rahead(rip, baseblock, position, bytes_ahead)
register struct inode *rip; /* pointer to inode for file to be read */
block_t baseblock; /* block at current position */
u64_t position; /* position within file */
unsigned bytes_ahead; /* bytes beyond position for immediate use */
{
/* Fetch a block from the cache or the device. If a physical read is
* required, prefetch as many more blocks as convenient into the cache.
* This usually covers bytes_ahead and is at least BLOCKS_MINIMUM.
* The device driver may decide it knows better and stop reading at a
* cylinder boundary (or after an error). Rw_scattered() puts an optional
* flag on all reads to allow this.
*/
/* Minimum number of blocks to prefetch. */
# define BLOCKS_MINIMUM (nr_bufs < 50 ? 18 : 32)
int nr_bufs = lmfs_nr_bufs();
int block_spec, read_q_size;
unsigned int blocks_ahead, fragment, block_size;
block_t block, blocks_left;
off_t ind1_pos;
dev_t dev;
struct buf *bp = NULL;
static unsigned int readqsize = 0;
static struct buf **read_q = NULL;
u64_t position_running;
if(readqsize != nr_bufs) {
if(readqsize > 0) {
assert(read_q != NULL);
free(read_q);
read_q = NULL;
readqsize = 0;
}
assert(readqsize == 0);
assert(read_q == NULL);
if(!(read_q = malloc(sizeof(read_q[0])*nr_bufs)))
panic("couldn't allocate read_q");
readqsize = nr_bufs;
}
block_spec = (rip->i_mode & I_TYPE) == I_BLOCK_SPECIAL;
if (block_spec)
dev = (dev_t) rip->i_block[0];
else
dev = rip->i_dev;
assert(dev != NO_DEV);
block_size = get_block_size(dev);
block = baseblock;
fragment = position % block_size;
position -= fragment;
position_running = position;
bytes_ahead += fragment;
blocks_ahead = (bytes_ahead + block_size - 1) / block_size;
if(block_spec)
bp = get_block(dev, block, PREFETCH);
else
bp = lmfs_get_block_ino(dev, block, PREFETCH, rip->i_num, position);
assert(bp != NULL);
if (lmfs_dev(bp) != NO_DEV) return(bp);
/* The best guess for the number of blocks to prefetch: A lot.
* It is impossible to tell what the device looks like, so we don't even
* try to guess the geometry, but leave it to the driver.
*
* The floppy driver can read a full track with no rotational delay, and it
* avoids reading partial tracks if it can, so handing it enough buffers to
* read two tracks is perfect. (Two, because some diskette types have
* an odd number of sectors per track, so a block may span tracks.)
*
* The disk drivers don't try to be smart. With todays disks it is
* impossible to tell what the real geometry looks like, so it is best to
* read as much as you can. With luck the caching on the drive allows
* for a little time to start the next read.
*
* The current solution below is a bit of a hack, it just reads blocks from
* the current file position hoping that more of the file can be found. A
* better solution must look at the already available
* indirect blocks (but don't call read_map!).
*/
if (block_spec && rip->i_size == 0) {
blocks_left = (block_t) NR_IOREQS;
} else {
blocks_left = (block_t) (rip->i_size-ex64lo(position)+(block_size-1)) /
block_size;
/* Go for the first indirect block if we are in its neighborhood. */
if (!block_spec) {
ind1_pos = (EXT2_NDIR_BLOCKS) * block_size;
if ((off_t) ex64lo(position) <= ind1_pos && rip->i_size > ind1_pos) {
blocks_ahead++;
blocks_left++;
}
}
}
/* No more than the maximum request. */
if (blocks_ahead > NR_IOREQS) blocks_ahead = NR_IOREQS;
/* Read at least the minimum number of blocks, but not after a seek. */
if (blocks_ahead < BLOCKS_MINIMUM && rip->i_seek == NO_SEEK)
blocks_ahead = BLOCKS_MINIMUM;
/* Can't go past end of file. */
if (blocks_ahead > blocks_left) blocks_ahead = blocks_left;
read_q_size = 0;
/* Acquire block buffers. */
for (;;) {
block_t thisblock;
read_q[read_q_size++] = bp;
if (--blocks_ahead == 0) break;
/* Don't trash the cache, leave 4 free. */
if (lmfs_bufs_in_use() >= nr_bufs - 4) break;
block++;
position_running += block_size;
if(!block_spec &&
(thisblock = read_map(rip, (off_t) ex64lo(position_running), 1)) != NO_BLOCK) {
bp = lmfs_get_block_ino(dev, thisblock, PREFETCH, rip->i_num, position_running);
} else {
bp = get_block(dev, block, PREFETCH);
}
if (lmfs_dev(bp) != NO_DEV) {
/* Oops, block already in the cache, get out. */
put_block(bp, FULL_DATA_BLOCK);
break;
}
}
lmfs_rw_scattered(dev, read_q, read_q_size, READING);
if(block_spec)
return get_block(dev, baseblock, NORMAL);
return(lmfs_get_block_ino(dev, baseblock, NORMAL, rip->i_num, position));
}
/*===========================================================================*
* fs_getdents_321 *
*===========================================================================*/
static int fs_getdents_321(void)
{
#define GETDENTS_321_BUFSIZE (sizeof(struct dirent_321) + EXT2_NAME_MAX + 1)
#define GETDENTS_321_ENTRIES 8
static char getdents_buf[GETDENTS_321_BUFSIZE * GETDENTS_321_ENTRIES];
struct inode *rip;
int o, r, done;
unsigned int block_size, len, reclen;
pino_t ino;
block_t b;
cp_grant_id_t gid;
size_t size, tmpbuf_off, userbuf_off;
off_t pos, off, block_pos, new_pos, ent_pos;
struct buf *bp;
struct ext2_disk_dir_desc *d_desc;
struct dirent *dep;
ino = (pino_t) fs_m_in.REQ_INODE_NR;
gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
size = (size_t) fs_m_in.REQ_MEM_SIZE;
pos = (off_t) fs_m_in.REQ_SEEK_POS_LO;
/* Check whether the position is properly aligned */
if ((unsigned int) pos % DIR_ENTRY_ALIGN)
return(ENOENT);
if ((rip = get_inode(fs_dev, ino)) == NULL)
return(EINVAL);
block_size = rip->i_sp->s_block_size;
off = (pos % block_size); /* Offset in block */
block_pos = pos - off;
done = FALSE; /* Stop processing directory blocks when done is set */
memset(getdents_buf, '\0', sizeof(getdents_buf)); /* Avoid leaking any data */
tmpbuf_off = 0; /* Offset in getdents_buf */
userbuf_off = 0; /* Offset in the user's buffer */
/* The default position for the next request is EOF. If the user's buffer
* fills up before EOF, new_pos will be modified. */
new_pos = rip->i_size;
for (; block_pos < rip->i_size; block_pos += block_size) {
off_t temp_pos = block_pos;
b = read_map(rip, block_pos, 0); /* get block number */
/* Since directories don't have holes, 'b' cannot be NO_BLOCK. */
bp = get_block(rip->i_dev, b, NORMAL); /* get a dir block */
assert(bp != NULL);
/* Search a directory block. */
d_desc = (struct ext2_disk_dir_desc*) &b_data(bp);
/* we need to seek to entry at off bytes.
* when NEXT_DISC_DIR_POS == block_size it's last dentry.
*/
for (; temp_pos + conv2(le_CPU, d_desc->d_rec_len) <= pos
&& NEXT_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size;
d_desc = NEXT_DISC_DIR_DESC(d_desc)) {
temp_pos += conv2(le_CPU, d_desc->d_rec_len);
}
for (; CUR_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size;
d_desc = NEXT_DISC_DIR_DESC(d_desc)) {
if (d_desc->d_ino == 0)
continue; /* Entry is not in use */
#if 0 /* d_nam_len is a uint8_t, so the test is always false. */
if (d_desc->d_name_len > NAME_MAX ||
d_desc->d_name_len > EXT2_NAME_MAX) {
len = min(NAME_MAX, EXT2_NAME_MAX);
} else {
len = d_desc->d_name_len;
}
#endif
len = d_desc->d_name_len;
/* Compute record length */
reclen = offsetof(struct dirent_321, d_name) + len + 1;
o = (reclen % sizeof(long));
if (o != 0)
reclen += sizeof(long) - o;
/* Need the position of this entry in the directory */
ent_pos = block_pos + ((char *)d_desc - b_data(bp));
if (userbuf_off + tmpbuf_off + reclen >= size) {
/* The user has no space for one more record */
done = TRUE;
/* Record the position of this entry, it is the
* starting point of the next request (unless the
* position is modified with lseek).
*/
new_pos = ent_pos;
break;
}
if (tmpbuf_off + reclen >=
GETDENTS_321_BUFSIZE * GETDENTS_321_ENTRIES) {
r = sys_safecopyto(VFS_PROC_NR, gid,
(vir_bytes) userbuf_off,
(vir_bytes) getdents_buf,
(size_t) tmpbuf_off);
if (r != OK) {
put_inode(rip);
return(r);
}
userbuf_off += tmpbuf_off;
tmpbuf_off = 0;
}
dep = (struct dirent *) &getdents_buf[tmpbuf_off];
dep->d_ino = (u32_t) conv4(le_CPU, d_desc->d_ino);
dep->d_off = (i32_t) ent_pos;
dep->d_reclen = (unsigned short) reclen;
memcpy(dep->d_name, d_desc->d_name, len);
dep->d_name[len] = '\0';
tmpbuf_off += reclen;
}
put_block(bp, DIRECTORY_BLOCK);
if (done)
break;
}
if (tmpbuf_off != 0) {
r = sys_safecopyto(VFS_PROC_NR, gid, (vir_bytes) userbuf_off,
(vir_bytes) getdents_buf, (size_t) tmpbuf_off);
if (r != OK) {
put_inode(rip);
return(r);
}
userbuf_off += tmpbuf_off;
}
if (done && userbuf_off == 0)
r = EINVAL; /* The user's buffer is too small */
else {
fs_m_out.RES_NBYTES = userbuf_off;
fs_m_out.RES_SEEK_POS_LO = new_pos;
rip->i_update |= ATIME;
rip->i_dirt = IN_DIRTY;
r = OK;
}
put_inode(rip); /* release the inode */
return(r);
}
/*===========================================================================*
* fs_getdents *
*===========================================================================*/
int fs_getdents(void)
{
#define GETDENTS_BUFSIZE (sizeof(struct dirent) + EXT2_NAME_MAX + 1)
#define GETDENTS_ENTRIES 8
static char getdents_buf[GETDENTS_BUFSIZE * GETDENTS_ENTRIES];
struct inode *rip;
int o, r, done;
unsigned int block_size, len, reclen;
pino_t ino;
cp_grant_id_t gid;
size_t size, tmpbuf_off, userbuf_off;
off_t pos, off, block_pos, new_pos, ent_pos;
struct buf *bp;
struct ext2_disk_dir_desc *d_desc;
struct dirent *dep;
if (proto_version == 0) {
return fs_getdents_321();
}
ino = (pino_t) fs_m_in.REQ_INODE_NR;
gid = (cp_grant_id_t) fs_m_in.REQ_GRANT;
size = (size_t) fs_m_in.REQ_MEM_SIZE;
pos = (off_t) fs_m_in.REQ_SEEK_POS_LO;
/* Check whether the position is properly aligned */
if ((unsigned int) pos % DIR_ENTRY_ALIGN)
return(ENOENT);
if ((rip = get_inode(fs_dev, ino)) == NULL)
return(EINVAL);
block_size = rip->i_sp->s_block_size;
off = (pos % block_size); /* Offset in block */
block_pos = pos - off;
done = FALSE; /* Stop processing directory blocks when done is set */
memset(getdents_buf, '\0', sizeof(getdents_buf)); /* Avoid leaking any data */
tmpbuf_off = 0; /* Offset in getdents_buf */
userbuf_off = 0; /* Offset in the user's buffer */
/* The default position for the next request is EOF. If the user's buffer
* fills up before EOF, new_pos will be modified. */
new_pos = rip->i_size;
for (; block_pos < rip->i_size; block_pos += block_size) {
off_t temp_pos = block_pos;
/* Since directories don't have holes, 'bp' cannot be NULL. */
bp = get_block_map(rip, block_pos); /* get a dir block */
assert(bp != NULL);
assert(bp != NULL);
/* Search a directory block. */
d_desc = (struct ext2_disk_dir_desc*) &b_data(bp);
/* we need to seek to entry at off bytes.
* when NEXT_DISC_DIR_POS == block_size it's last dentry.
*/
for (; temp_pos + conv2(le_CPU, d_desc->d_rec_len) <= pos
&& NEXT_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size;
d_desc = NEXT_DISC_DIR_DESC(d_desc)) {
temp_pos += conv2(le_CPU, d_desc->d_rec_len);
}
for (; CUR_DISC_DIR_POS(d_desc, &b_data(bp)) < block_size;
d_desc = NEXT_DISC_DIR_DESC(d_desc)) {
if (d_desc->d_ino == 0)
continue; /* Entry is not in use */
#if 0
/* read.c:682: error: comparison is always false due to
* limited range of data type
*/
if (d_desc->d_name_len > NAME_MAX ||
d_desc->d_name_len > EXT2_NAME_MAX) {
len = min(NAME_MAX, EXT2_NAME_MAX);
} else
#endif
{
len = d_desc->d_name_len;
}
assert(len <= NAME_MAX);
assert(len <= EXT2_NAME_MAX);
/* Compute record length */
reclen = offsetof(struct dirent, d_name) + len + 1;
o = (reclen % sizeof(long));
if (o != 0)
reclen += sizeof(long) - o;
/* Need the position of this entry in the directory */
ent_pos = block_pos + ((char *)d_desc - b_data(bp));
if (userbuf_off + tmpbuf_off + reclen >= size) {
/* The user has no space for one more record */
done = TRUE;
/* Record the position of this entry, it is the
* starting point of the next request (unless the
* position is modified with lseek).
*/
new_pos = ent_pos;
break;
}
if (tmpbuf_off + reclen >= GETDENTS_BUFSIZE*GETDENTS_ENTRIES) {
r = sys_safecopyto(VFS_PROC_NR, gid,
(vir_bytes) userbuf_off,
(vir_bytes) getdents_buf,
(size_t) tmpbuf_off);
if (r != OK) {
put_inode(rip);
return(r);
}
userbuf_off += tmpbuf_off;
tmpbuf_off = 0;
}
dep = (struct dirent *) &getdents_buf[tmpbuf_off];
dep->d_ino = (ino_t) conv4(le_CPU, d_desc->d_ino);
dep->d_off = (off_t) ent_pos;
dep->d_reclen = (unsigned short) reclen;
memcpy(dep->d_name, d_desc->d_name, len);
dep->d_name[len] = '\0';
tmpbuf_off += reclen;
}
put_block(bp, DIRECTORY_BLOCK);
if (done)
break;
}
if (tmpbuf_off != 0) {
r = sys_safecopyto(VFS_PROC_NR, gid, (vir_bytes) userbuf_off,
(vir_bytes) getdents_buf, (size_t) tmpbuf_off);
if (r != OK) {
put_inode(rip);
return(r);
}
userbuf_off += tmpbuf_off;
}
if (done && userbuf_off == 0)
r = EINVAL; /* The user's buffer is too small */
else {
fs_m_out.RES_NBYTES = userbuf_off;
fs_m_out.RES_SEEK_POS_LO = new_pos;
rip->i_update |= ATIME;
rip->i_dirt = IN_DIRTY;
r = OK;
}
put_inode(rip); /* release the inode */
return(r);
}
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