376 lines
12 KiB
C
376 lines
12 KiB
C
/* This file contains the procedures that look up path names in the directory
|
|
* system and determine the inode number that goes with a given path name.
|
|
*
|
|
* The entry points into this file are
|
|
* eat_path: the 'main' routine of the path-to-inode conversion mechanism
|
|
* last_dir: find the final directory on a given path
|
|
* advance: parse one component of a path name
|
|
* search_dir: search a directory for a string and return its inode number
|
|
*/
|
|
|
|
#include "fs.h"
|
|
#include <string.h>
|
|
#include <minix/callnr.h>
|
|
#include "buf.h"
|
|
#include "file.h"
|
|
#include "fproc.h"
|
|
#include "inode.h"
|
|
#include "super.h"
|
|
|
|
PUBLIC char dot1[2] = "."; /* used for search_dir to bypass the access */
|
|
PUBLIC char dot2[3] = ".."; /* permissions for . and .. */
|
|
|
|
FORWARD _PROTOTYPE( char *get_name, (char *old_name, char string [NAME_MAX]) );
|
|
|
|
/*===========================================================================*
|
|
* eat_path *
|
|
*===========================================================================*/
|
|
PUBLIC struct inode *eat_path(path)
|
|
char *path; /* the path name to be parsed */
|
|
{
|
|
/* Parse the path 'path' and put its inode in the inode table. If not possible,
|
|
* return NIL_INODE as function value and an error code in 'err_code'.
|
|
*/
|
|
|
|
register struct inode *ldip, *rip;
|
|
char string[NAME_MAX]; /* hold 1 path component name here */
|
|
|
|
/* First open the path down to the final directory. */
|
|
if ( (ldip = last_dir(path, string)) == NIL_INODE) {
|
|
return(NIL_INODE); /* we couldn't open final directory */
|
|
}
|
|
|
|
/* The path consisting only of "/" is a special case, check for it. */
|
|
if (string[0] == '\0') return(ldip);
|
|
|
|
/* Get final component of the path. */
|
|
rip = advance(ldip, string);
|
|
put_inode(ldip);
|
|
return(rip);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* last_dir *
|
|
*===========================================================================*/
|
|
PUBLIC struct inode *last_dir(path, string)
|
|
char *path; /* the path name to be parsed */
|
|
char string[NAME_MAX]; /* the final component is returned here */
|
|
{
|
|
/* Given a path, 'path', located in the fs address space, parse it as
|
|
* far as the last directory, fetch the inode for the last directory into
|
|
* the inode table, and return a pointer to the inode. In
|
|
* addition, return the final component of the path in 'string'.
|
|
* If the last directory can't be opened, return NIL_INODE and
|
|
* the reason for failure in 'err_code'.
|
|
*/
|
|
|
|
register struct inode *rip;
|
|
register char *new_name;
|
|
register struct inode *new_ip;
|
|
|
|
/* Is the path absolute or relative? Initialize 'rip' accordingly. */
|
|
rip = (*path == '/' ? fp->fp_rootdir : fp->fp_workdir);
|
|
|
|
/* If dir has been removed or path is empty, return ENOENT. */
|
|
if (rip->i_nlinks == 0 || *path == '\0') {
|
|
err_code = ENOENT;
|
|
return(NIL_INODE);
|
|
}
|
|
|
|
dup_inode(rip); /* inode will be returned with put_inode */
|
|
|
|
/* Scan the path component by component. */
|
|
while (TRUE) {
|
|
/* Extract one component. */
|
|
if ( (new_name = get_name(path, string)) == (char*) 0) {
|
|
put_inode(rip); /* bad path in user space */
|
|
return(NIL_INODE);
|
|
}
|
|
if (*new_name == '\0')
|
|
if ( (rip->i_mode & I_TYPE) == I_DIRECTORY) {
|
|
return(rip); /* normal exit */
|
|
} else {
|
|
/* last file of path prefix is not a directory */
|
|
put_inode(rip);
|
|
err_code = ENOTDIR;
|
|
return(NIL_INODE);
|
|
}
|
|
|
|
/* There is more path. Keep parsing. */
|
|
new_ip = advance(rip, string);
|
|
put_inode(rip); /* rip either obsolete or irrelevant */
|
|
if (new_ip == NIL_INODE) return(NIL_INODE);
|
|
|
|
/* The call to advance() succeeded. Fetch next component. */
|
|
path = new_name;
|
|
rip = new_ip;
|
|
}
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* get_name *
|
|
*===========================================================================*/
|
|
PRIVATE char *get_name(old_name, string)
|
|
char *old_name; /* path name to parse */
|
|
char string[NAME_MAX]; /* component extracted from 'old_name' */
|
|
{
|
|
/* Given a pointer to a path name in fs space, 'old_name', copy the next
|
|
* component to 'string' and pad with zeros. A pointer to that part of
|
|
* the name as yet unparsed is returned. Roughly speaking,
|
|
* 'get_name' = 'old_name' - 'string'.
|
|
*
|
|
* This routine follows the standard convention that /usr/ast, /usr//ast,
|
|
* //usr///ast and /usr/ast/ are all equivalent.
|
|
*/
|
|
|
|
register int c;
|
|
register char *np, *rnp;
|
|
|
|
np = string; /* 'np' points to current position */
|
|
rnp = old_name; /* 'rnp' points to unparsed string */
|
|
while ( (c = *rnp) == '/') rnp++; /* skip leading slashes */
|
|
|
|
/* Copy the unparsed path, 'old_name', to the array, 'string'. */
|
|
while ( rnp < &old_name[PATH_MAX] && c != '/' && c != '\0') {
|
|
if (np < &string[NAME_MAX]) *np++ = c;
|
|
c = *++rnp; /* advance to next character */
|
|
}
|
|
|
|
/* To make /usr/ast/ equivalent to /usr/ast, skip trailing slashes. */
|
|
while (c == '/' && rnp < &old_name[PATH_MAX]) c = *++rnp;
|
|
|
|
if (np < &string[NAME_MAX]) *np = '\0'; /* Terminate string */
|
|
|
|
if (rnp >= &old_name[PATH_MAX]) {
|
|
err_code = ENAMETOOLONG;
|
|
return((char *) 0);
|
|
}
|
|
return(rnp);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* advance *
|
|
*===========================================================================*/
|
|
PUBLIC struct inode *advance(dirp, string)
|
|
struct inode *dirp; /* inode for directory to be searched */
|
|
char string[NAME_MAX]; /* component name to look for */
|
|
{
|
|
/* Given a directory and a component of a path, look up the component in
|
|
* the directory, find the inode, open it, and return a pointer to its inode
|
|
* slot. If it can't be done, return NIL_INODE.
|
|
*/
|
|
|
|
register struct inode *rip;
|
|
struct inode *rip2;
|
|
register struct super_block *sp;
|
|
int r, inumb;
|
|
dev_t mnt_dev;
|
|
ino_t numb;
|
|
|
|
/* If 'string' is empty, yield same inode straight away. */
|
|
if (string[0] == '\0') { return(get_inode(dirp->i_dev, (int) dirp->i_num)); }
|
|
|
|
/* Check for NIL_INODE. */
|
|
if (dirp == NIL_INODE) { return(NIL_INODE); }
|
|
|
|
/* If 'string' is not present in the directory, signal error. */
|
|
if ( (r = search_dir(dirp, string, &numb, LOOK_UP)) != OK) {
|
|
err_code = r;
|
|
return(NIL_INODE);
|
|
}
|
|
|
|
/* Don't go beyond the current root directory, unless the string is dot2. */
|
|
if (dirp == fp->fp_rootdir && strcmp(string, "..") == 0 && string != dot2)
|
|
return(get_inode(dirp->i_dev, (int) dirp->i_num));
|
|
|
|
/* The component has been found in the directory. Get inode. */
|
|
if ( (rip = get_inode(dirp->i_dev, (int) numb)) == NIL_INODE) {
|
|
return(NIL_INODE);
|
|
}
|
|
|
|
if (rip->i_num == ROOT_INODE)
|
|
if (dirp->i_num == ROOT_INODE) {
|
|
if (string[1] == '.') {
|
|
for (sp = &super_block[1]; sp < &super_block[NR_SUPERS]; sp++){
|
|
if (sp->s_dev == rip->i_dev) {
|
|
/* Release the root inode. Replace by the
|
|
* inode mounted on.
|
|
*/
|
|
put_inode(rip);
|
|
mnt_dev = sp->s_imount->i_dev;
|
|
inumb = (int) sp->s_imount->i_num;
|
|
rip2 = get_inode(mnt_dev, inumb);
|
|
rip = advance(rip2, string);
|
|
put_inode(rip2);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (rip == NIL_INODE) return(NIL_INODE);
|
|
|
|
/* See if the inode is mounted on. If so, switch to root directory of the
|
|
* mounted file system. The super_block provides the linkage between the
|
|
* inode mounted on and the root directory of the mounted file system.
|
|
*/
|
|
while (rip != NIL_INODE && rip->i_mount == I_MOUNT) {
|
|
/* The inode is indeed mounted on. */
|
|
for (sp = &super_block[0]; sp < &super_block[NR_SUPERS]; sp++) {
|
|
if (sp->s_imount == rip) {
|
|
/* Release the inode mounted on. Replace by the
|
|
* inode of the root inode of the mounted device.
|
|
*/
|
|
put_inode(rip);
|
|
rip = get_inode(sp->s_dev, ROOT_INODE);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return(rip); /* return pointer to inode's component */
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* search_dir *
|
|
*===========================================================================*/
|
|
PUBLIC int search_dir(ldir_ptr, string, numb, flag)
|
|
register struct inode *ldir_ptr; /* ptr to inode for dir to search */
|
|
char string[NAME_MAX]; /* component to search for */
|
|
ino_t *numb; /* pointer to inode number */
|
|
int flag; /* LOOK_UP, ENTER, DELETE or IS_EMPTY */
|
|
{
|
|
/* This function searches the directory whose inode is pointed to by 'ldip':
|
|
* if (flag == ENTER) enter 'string' in the directory with inode # '*numb';
|
|
* if (flag == DELETE) delete 'string' from the directory;
|
|
* if (flag == LOOK_UP) search for 'string' and return inode # in 'numb';
|
|
* if (flag == IS_EMPTY) return OK if only . and .. in dir else ENOTEMPTY;
|
|
*
|
|
* if 'string' is dot1 or dot2, no access permissions are checked.
|
|
*/
|
|
|
|
register struct direct *dp;
|
|
register struct buf *bp;
|
|
int i, r, e_hit, t, match;
|
|
mode_t bits;
|
|
off_t pos;
|
|
unsigned new_slots, old_slots;
|
|
block_t b;
|
|
struct super_block *sp;
|
|
int extended = 0;
|
|
|
|
/* If 'ldir_ptr' is not a pointer to a dir inode, error. */
|
|
if ( (ldir_ptr->i_mode & I_TYPE) != I_DIRECTORY) return(ENOTDIR);
|
|
|
|
r = OK;
|
|
|
|
if (flag != IS_EMPTY) {
|
|
bits = (flag == LOOK_UP ? X_BIT : W_BIT | X_BIT);
|
|
|
|
if (string == dot1 || string == dot2) {
|
|
if (flag != LOOK_UP) r = read_only(ldir_ptr);
|
|
/* only a writable device is required. */
|
|
}
|
|
else r = forbidden(ldir_ptr, bits); /* check access permissions */
|
|
}
|
|
if (r != OK) return(r);
|
|
|
|
/* Step through the directory one block at a time. */
|
|
old_slots = (unsigned) (ldir_ptr->i_size/DIR_ENTRY_SIZE);
|
|
new_slots = 0;
|
|
e_hit = FALSE;
|
|
match = 0; /* set when a string match occurs */
|
|
|
|
for (pos = 0; pos < ldir_ptr->i_size; pos += ldir_ptr->i_sp->s_block_size) {
|
|
b = read_map(ldir_ptr, pos); /* get block number */
|
|
|
|
/* Since directories don't have holes, 'b' cannot be NO_BLOCK. */
|
|
bp = get_block(ldir_ptr->i_dev, b, NORMAL); /* get a dir block */
|
|
|
|
if(bp == NO_BLOCK)
|
|
panic(__FILE__,"get_block returned NO_BLOCK", NO_NUM);
|
|
|
|
/* Search a directory block. */
|
|
for (dp = &bp->b_dir[0]; dp < &bp->b_dir[NR_DIR_ENTRIES(ldir_ptr->i_sp->s_block_size)]; dp++) {
|
|
if (++new_slots > old_slots) { /* not found, but room left */
|
|
if (flag == ENTER) e_hit = TRUE;
|
|
break;
|
|
}
|
|
|
|
/* Match occurs if string found. */
|
|
if (flag != ENTER && dp->d_ino != 0) {
|
|
if (flag == IS_EMPTY) {
|
|
/* If this test succeeds, dir is not empty. */
|
|
if (strcmp(dp->d_name, "." ) != 0 &&
|
|
strcmp(dp->d_name, "..") != 0) match = 1;
|
|
} else {
|
|
if (strncmp(dp->d_name, string, NAME_MAX) == 0) {
|
|
match = 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (match) {
|
|
/* LOOK_UP or DELETE found what it wanted. */
|
|
r = OK;
|
|
if (flag == IS_EMPTY) r = ENOTEMPTY;
|
|
else if (flag == DELETE) {
|
|
/* Save d_ino for recovery. */
|
|
t = NAME_MAX - sizeof(ino_t);
|
|
*((ino_t *) &dp->d_name[t]) = dp->d_ino;
|
|
dp->d_ino = 0; /* erase entry */
|
|
bp->b_dirt = DIRTY;
|
|
ldir_ptr->i_update |= CTIME | MTIME;
|
|
ldir_ptr->i_dirt = DIRTY;
|
|
} else {
|
|
sp = ldir_ptr->i_sp; /* 'flag' is LOOK_UP */
|
|
*numb = conv4(sp->s_native, (int) dp->d_ino);
|
|
}
|
|
put_block(bp, DIRECTORY_BLOCK);
|
|
return(r);
|
|
}
|
|
|
|
/* Check for free slot for the benefit of ENTER. */
|
|
if (flag == ENTER && dp->d_ino == 0) {
|
|
e_hit = TRUE; /* we found a free slot */
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* The whole block has been searched or ENTER has a free slot. */
|
|
if (e_hit) break; /* e_hit set if ENTER can be performed now */
|
|
put_block(bp, DIRECTORY_BLOCK); /* otherwise, continue searching dir */
|
|
}
|
|
|
|
/* The whole directory has now been searched. */
|
|
if (flag != ENTER) {
|
|
return(flag == IS_EMPTY ? OK : ENOENT);
|
|
}
|
|
|
|
/* This call is for ENTER. If no free slot has been found so far, try to
|
|
* extend directory.
|
|
*/
|
|
if (e_hit == FALSE) { /* directory is full and no room left in last block */
|
|
new_slots++; /* increase directory size by 1 entry */
|
|
if (new_slots == 0) return(EFBIG); /* dir size limited by slot count */
|
|
if ( (bp = new_block(ldir_ptr, ldir_ptr->i_size)) == NIL_BUF)
|
|
return(err_code);
|
|
dp = &bp->b_dir[0];
|
|
extended = 1;
|
|
}
|
|
|
|
/* 'bp' now points to a directory block with space. 'dp' points to slot. */
|
|
(void) memset(dp->d_name, 0, (size_t) NAME_MAX); /* clear entry */
|
|
for (i = 0; string[i] && i < NAME_MAX; i++) dp->d_name[i] = string[i];
|
|
sp = ldir_ptr->i_sp;
|
|
dp->d_ino = conv4(sp->s_native, (int) *numb);
|
|
bp->b_dirt = DIRTY;
|
|
put_block(bp, DIRECTORY_BLOCK);
|
|
ldir_ptr->i_update |= CTIME | MTIME; /* mark mtime for update later */
|
|
ldir_ptr->i_dirt = DIRTY;
|
|
if (new_slots > old_slots) {
|
|
ldir_ptr->i_size = (off_t) new_slots * DIR_ENTRY_SIZE;
|
|
/* Send the change to disk if the directory is extended. */
|
|
if (extended) rw_inode(ldir_ptr, WRITING);
|
|
}
|
|
return(OK);
|
|
}
|