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