minix/servers/mfs/open.c
Thomas Veerman 958b25be50 - Introduce support for sticky bit.
- Revise VFS-FS protocol and update VFS/MFS/ISOFS accordingly.
- Clean up MFS by removing old, dead code (backwards compatibility is broken by
  the new VFS-FS protocol, anyway) and rewrite other parts. Also, make sure all
  functions have proper banners and prototypes.
- VFS should always provide a (syntactically) valid path to the FS; no need for
  the FS to do sanity checks when leaving/entering mount points.
- Fix several bugs in MFS:
  - Several path lookup bugs in MFS.
  - A link can be too big for the path buffer.
  - A mountpoint can become inaccessible when the creation of a new inode
    fails, because the inode already exists and is a mountpoint.
- Introduce support for supplemental groups.
- Add test 46 to test supplemental group functionality (and removed obsolete
  suppl. tests from test 2).
- Clean up VFS (not everything is done yet).
- ISOFS now opens device read-only. This makes the -r flag in the mount command
  unnecessary (but will still report to be mounted read-write).
- Introduce PipeFS. PipeFS is a new FS that handles all anonymous and
  named pipes. However, named pipes still reside on the (M)FS, as they are part
  of the file system on disk. To make this work VFS now has a concept of
  'mapped' inodes, which causes read, write, truncate and stat requests to be
  redirected to the mapped FS, and all other requests to the original FS.
2009-12-20 20:27:14 +00:00

373 lines
12 KiB
C

#include "fs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include "buf.h"
#include "inode.h"
#include "super.h"
#include <minix/vfsif.h>
PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
FORWARD _PROTOTYPE( struct inode *new_node, (struct inode *ldirp,
char *string, mode_t bits, zone_t z0));
/*===========================================================================*
* fs_create *
*===========================================================================*/
PUBLIC int fs_create()
{
phys_bytes len;
int r, b;
struct inode *ldirp;
struct inode *rip;
mode_t omode;
char lastc[NAME_MAX];
/* Read request message */
omode = fs_m_in.REQ_MODE;
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Try to make the file. */
/* Copy the last component (i.e., file name) */
len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(FS_PROC_NR, fs_m_in.REQ_GRANT, 0,
(vir_bytes) lastc, (phys_bytes) len, D);
if (err_code != OK) return err_code;
MFS_NUL(lastc, len, sizeof(lastc));
/* Get last directory inode (i.e., directory that will hold the new inode) */
if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE)
return(ENOENT);
/* Create a new inode by calling new_node(). */
rip = new_node(ldirp, lastc, omode, NO_ZONE);
r = err_code;
/* If an error occurred, release inode. */
if (r != OK) {
put_inode(ldirp);
put_inode(rip);
return(r);
}
/* Reply message */
fs_m_out.m_source = rip->i_dev; /* filled with FS endpoint by the system */
fs_m_out.RES_INODE_NR = rip->i_num;
fs_m_out.RES_MODE = rip->i_mode;
fs_m_out.RES_FILE_SIZE_LO = rip->i_size;
/* This values are needed for the execution */
fs_m_out.RES_UID = rip->i_uid;
fs_m_out.RES_GID = rip->i_gid;
/* Drop parent dir */
put_inode(ldirp);
return(OK);
}
/*===========================================================================*
* fs_mknod *
*===========================================================================*/
PUBLIC int fs_mknod()
{
struct inode *ip, *ldirp;
char lastc[NAME_MAX];
phys_bytes len;
/* Copy the last component and set up caller's user and group id */
len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(FS_PROC_NR, fs_m_in.REQ_GRANT, 0,
(vir_bytes) lastc, (phys_bytes) len, D);
if (err_code != OK) return err_code;
MFS_NUL(lastc, len, sizeof(lastc));
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Get last directory inode */
if((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE)
return(ENOENT);
/* Try to create the new node */
ip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) fs_m_in.REQ_DEV);
put_inode(ip);
put_inode(ldirp);
return(err_code);
}
/*===========================================================================*
* fs_mkdir *
*===========================================================================*/
PUBLIC int fs_mkdir()
{
int r1, r2; /* status codes */
ino_t dot, dotdot; /* inode numbers for . and .. */
struct inode *rip, *ldirp;
char lastc[NAME_MAX]; /* last component */
phys_bytes len;
/* Copy the last component and set up caller's user and group id */
len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(FS_PROC_NR, fs_m_in.REQ_GRANT, 0,
(vir_bytes) lastc, (phys_bytes) len, D);
if(err_code != OK) return(err_code);
MFS_NUL(lastc, len, sizeof(lastc));
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Get last directory inode */
if((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE)
return(ENOENT);
/* Next make the inode. If that fails, return error code. */
rip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) 0);
if(rip == NIL_INODE || err_code == EEXIST) {
put_inode(rip); /* can't make dir: it already exists */
put_inode(ldirp);
return(err_code);
}
/* Get the inode numbers for . and .. to enter in the directory. */
dotdot = ldirp->i_num; /* parent's inode number */
dot = rip->i_num; /* inode number of the new dir itself */
/* Now make dir entries for . and .. unless the disk is completely full. */
/* Use dot1 and dot2, so the mode of the directory isn't important. */
rip->i_mode = fs_m_in.REQ_MODE; /* set mode */
r1 = search_dir(rip, dot1, &dot, ENTER, IGN_PERM);/* enter . in the new dir*/
r2 = search_dir(rip, dot2, &dotdot, ENTER, IGN_PERM); /* enter .. in the new
dir */
/* If both . and .. were successfully entered, increment the link counts. */
if (r1 == OK && r2 == OK) {
/* Normal case. It was possible to enter . and .. in the new dir. */
rip->i_nlinks++; /* this accounts for . */
ldirp->i_nlinks++; /* this accounts for .. */
ldirp->i_dirt = DIRTY; /* mark parent's inode as dirty */
} else {
/* It was not possible to enter . or .. probably disk was full -
* links counts haven't been touched. */
if(search_dir(ldirp, lastc, (ino_t *) 0, DELETE, IGN_PERM) != OK)
panic(__FILE__, "Dir disappeared ", rip->i_num);
rip->i_nlinks--; /* undo the increment done in new_node() */
}
rip->i_dirt = DIRTY; /* either way, i_nlinks has changed */
put_inode(ldirp); /* return the inode of the parent dir */
put_inode(rip); /* return the inode of the newly made dir */
return(err_code); /* new_node() always sets 'err_code' */
}
/*===========================================================================*
* fs_slink *
*===========================================================================*/
PUBLIC int fs_slink()
{
phys_bytes len;
struct inode *sip; /* inode containing symbolic link */
struct inode *ldirp; /* directory containing link */
register int r; /* error code */
char string[NAME_MAX]; /* last component of the new dir's path name */
struct buf *bp; /* disk buffer for link */
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Copy the link name's last component */
len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(string));
r = sys_safecopyfrom(FS_PROC_NR, fs_m_in.REQ_GRANT, 0,
(vir_bytes) string, (phys_bytes) len, D);
if (r != OK) return(r);
MFS_NUL(string, len, sizeof(string));
/* Temporarily open the dir. */
if( (ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE)
return(EINVAL);
/* Create the inode for the symlink. */
sip = new_node(ldirp, string, (mode_t) (I_SYMBOLIC_LINK | RWX_MODES),
(zone_t) 0);
/* Allocate a disk block for the contents of the symlink.
* Copy contents of symlink (the name pointed to) into first disk block. */
if( (r = err_code) == OK) {
r = (bp = new_block(sip, (off_t) 0)) == NIL_BUF ? err_code :
sys_safecopyfrom(FS_PROC_NR, fs_m_in.REQ_GRANT3, 0,
(vir_bytes) bp->b_data,
(vir_bytes) fs_m_in.REQ_MEM_SIZE, D);
if(r == OK) {
bp->b_data[_MIN_BLOCK_SIZE-1] = '\0';
sip->i_size = strlen(bp->b_data);
if(sip->i_size != fs_m_in.REQ_MEM_SIZE) {
/* This can happen if the user provides a buffer
* with a \0 in it. This can cause a lot of trouble
* when the symlink is used later. We could just use
* the strlen() value, but we want to let the user
* know he did something wrong. ENAMETOOLONG doesn't
* exactly describe the error, but there is no
* ENAMETOOWRONG.
*/
r = ENAMETOOLONG;
}
}
put_block(bp, DIRECTORY_BLOCK); /* put_block() accepts NIL_BUF. */
if(r != OK) {
sip->i_nlinks = 0;
if(search_dir(ldirp, string, (ino_t *) 0, DELETE,
IGN_PERM) != OK)
panic(__FILE__, "Symbolic link vanished", NO_NUM);
}
}
/* put_inode() accepts NIL_INODE as a noop, so the below are safe. */
put_inode(sip);
put_inode(ldirp);
return(r);
}
/*===========================================================================*
* fs_newnode *
*===========================================================================*/
PUBLIC int fs_newnode()
{
register int r;
mode_t bits;
struct inode *rip;
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
bits = fs_m_in.REQ_MODE;
/* Try to allocate the inode */
if( (rip = alloc_inode(fs_dev, bits) ) == NIL_INODE)
return err_code;
switch (bits & S_IFMT) {
case S_IFBLK:
case S_IFCHR:
rip->i_zone[0] = fs_m_in.REQ_DEV; /* major/minor dev numbers*/
break;
}
rw_inode(rip, WRITING); /* mark inode as allocated */
rip->i_update = ATIME | CTIME | MTIME;
/* Fill in the fields of the response message */
fs_m_out.RES_INODE_NR = rip->i_num;
fs_m_out.RES_MODE = rip->i_mode;
fs_m_out.RES_FILE_SIZE_LO = rip->i_size;
fs_m_out.RES_UID = rip->i_uid;
fs_m_out.RES_GID = rip->i_gid;
fs_m_out.RES_DEV = (dev_t) rip->i_zone[0];
return(OK);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
PRIVATE struct inode *new_node(struct inode *ldirp,
char *string, mode_t bits, zone_t z0)
{
/* New_node() is called by fs_open(), fs_mknod(), and fs_mkdir().
* In all cases it allocates a new inode, makes a directory entry for it in
* the ldirp directory with string name, and initializes it.
* It returns a pointer to the inode if it can do this;
* otherwise it returns NIL_INODE. It always sets 'err_code'
* to an appropriate value (OK or an error code).
*
* The parsed path rest is returned in 'parsed' if parsed is nonzero. It
* has to hold at least NAME_MAX bytes.
*/
register struct inode *rip;
register int r;
/* Get final component of the path. */
rip = advance(ldirp, string, IGN_PERM);
if (S_ISDIR(bits) &&
(ldirp)->i_nlinks >= ((ldirp)->i_sp->s_version == V1 ?
CHAR_MAX : SHRT_MAX)) {
/* New entry is a directory, alas we can't give it a ".." */
put_inode(rip);
err_code = EMLINK;
return(NIL_INODE);
}
if ( rip == NIL_INODE && err_code == ENOENT) {
/* Last path component does not exist. Make new directory entry. */
if ( (rip = alloc_inode((ldirp)->i_dev, bits)) == NIL_INODE) {
/* Can't creat new inode: out of inodes. */
return(NIL_INODE);
}
/* Force inode to the disk before making directory entry to make
* the system more robust in the face of a crash: an inode with
* no directory entry is much better than the opposite.
*/
rip->i_nlinks++;
rip->i_zone[0] = z0; /* major/minor device numbers */
rw_inode(rip, WRITING); /* force inode to disk now */
/* New inode acquired. Try to make directory entry. */
if((r=search_dir(ldirp, string, &rip->i_num, ENTER, IGN_PERM)) != OK) {
rip->i_nlinks--; /* pity, have to free disk inode */
rip->i_dirt = DIRTY; /* dirty inodes are written out */
put_inode(rip); /* this call frees the inode */
err_code = r;
return(NIL_INODE);
}
} else if (err_code == EENTERMOUNT || err_code == ELEAVEMOUNT) {
r = EEXIST;
} else {
/* Either last component exists, or there is some problem. */
if (rip != NIL_INODE)
r = EEXIST;
else
r = err_code;
}
/* The caller has to return the directory inode (*ldirp). */
err_code = r;
return(rip);
}
/*===========================================================================*
* fs_inhibread *
*===========================================================================*/
PUBLIC int fs_inhibread()
{
struct inode *rip;
if((rip = find_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE)
return(EINVAL);
/* inhibit read ahead */
rip->i_seek = ISEEK;
return(OK);
}