a9d0ffbd0d
The next commit will make mode_t 32-bits, ino_t 64-bits, nlink_t 32-bits, and off_t 64-bits. However, in the protocol there is no room for that. When analyzing the usage of these data types we can see that of mode_t we currently use 15 bits and that future flags (if copied from NetBSD) are only of importance to VFS and not to the actual file system on disk. Therefore we can get away with keeping the protocol version of mode_t (pmode_t) 16 bits. At this point it is unlikely that MINIX will support file systems that can hold more than 2^32 files. Keeping the protocol version of ino_t (pino_t) 32-bits and exposing it as 64-bits to the rest of the system is fine. uid_t and gid_t are already 32-bits, but in behind the scenes they're 16-bits. This is sufficient since we don't support uid/gids larger than 2^16-1. off_t will become 64-bits, but the protocol had room reserved for that since it was revised years ago. So to make the difference clear between what the protocol supports and what is exposed to the system, we define protocol version of these data types. Change-Id: Ifb883aafb222142e69d6dcc3049a47170b78b3ee
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
#include "fs.h"
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#include "buf.h"
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#include "inode.h"
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#include <minix/com.h>
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#include <string.h>
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/*===========================================================================*
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* fs_readwrite *
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*===========================================================================*/
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int fs_readwrite(message *fs_m_in, message *fs_m_out)
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{
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int r, rw_flag;
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struct buf *bp;
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cp_grant_id_t gid;
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off_t position, f_size;
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unsigned int nrbytes, cum_io;
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pmode_t mode_word;
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struct inode *rip;
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pino_t inumb;
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r = OK;
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cum_io = 0;
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inumb = (pino_t) fs_m_in->REQ_INODE_NR;
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/* Find the inode referred */
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if ((rip = find_inode(inumb)) == NULL) return(EINVAL);
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mode_word = rip->i_mode & I_TYPE;
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if (mode_word != I_NAMED_PIPE) return(EIO);
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f_size = rip->i_size;
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/* Get the values from the request message */
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rw_flag = (fs_m_in->m_type == REQ_READ ? READING : WRITING);
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gid = (cp_grant_id_t) fs_m_in->REQ_GRANT;
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nrbytes = (unsigned) fs_m_in->REQ_NBYTES;
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/* We can't read beyond the max file position */
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if (nrbytes > PIPE_BUF) return(EFBIG);
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/* Mark inode in use */
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if ((get_inode(rip->i_dev, rip->i_num)) == NULL) return(err_code);
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if ((bp = get_block(rip->i_dev, rip->i_num)) == NULL) return(err_code);
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if (rw_flag == WRITING) {
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/* Check in advance to see if file will grow too big. */
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/* Casting nrbytes to signed is safe, because it's guaranteed not to
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* be beyond max signed value (i.e., MAX_FILE_POS).
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*/
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position = rip->i_size;
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if ((unsigned) position + nrbytes > PIPE_BUF) {
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put_inode(rip);
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put_block(rip->i_dev, rip->i_num);
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return(EFBIG);
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}
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} else {
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position = 0;
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if (nrbytes > rip->i_size) {
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/* There aren't that many bytes to read */
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nrbytes = rip->i_size;
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}
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}
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if (rw_flag == READING) {
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/* Copy a chunk from the block buffer to user space. */
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r = sys_safecopyto(VFS_PROC_NR, gid, (vir_bytes) 0,
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(vir_bytes) (bp->b_data+position), (size_t) nrbytes);
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} else {
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/* Copy a chunk from user space to the block buffer. */
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r = sys_safecopyfrom(VFS_PROC_NR, gid, (vir_bytes) 0,
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(vir_bytes) (bp->b_data+position), (size_t) nrbytes);
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}
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if (r == OK) {
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position += (signed) nrbytes; /* Update position */
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cum_io += nrbytes;
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}
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/* On write, update file size and access time. */
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if (rw_flag == WRITING) {
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rip->i_size = position;
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} else {
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memmove(bp->b_data, bp->b_data+nrbytes, rip->i_size - nrbytes);
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rip->i_size -= nrbytes;
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}
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if (rw_flag == READING) rip->i_update |= ATIME;
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if (rw_flag == WRITING) rip->i_update |= CTIME | MTIME;
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fs_m_out->RES_NBYTES = (size_t) cum_io;
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fs_m_out->RES_SEEK_POS_LO = rip->i_size;
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put_inode(rip);
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put_block(rip->i_dev, rip->i_num);
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return(r);
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}
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