fs/proc/link.c

/* */
This source file includes following definitions.
proc_follow_link
proc_readlink
   1 /*
   2  *  linux/fs/proc/link.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  /proc link-file handling code
   7  */
   8 
   9 #include <asm/segment.h>
  10 
  11 #include <linux/errno.h>
  12 #include <linux/sched.h>
  13 #include <linux/fs.h>
  14 #include <linux/minix_fs.h>
  15 #include <linux/stat.h>
  16 
  17 static int proc_readlink(struct inode *, char *, int);
  18 static int proc_follow_link(struct inode *, struct inode *, int, int, struct inode **);
  19 
  20 /*
  21  * links can't do much...
  22  */
  23 struct inode_operations proc_link_inode_operations = {
  24         NULL,                   /* no file-operations */
  25         NULL,                   /* create */
  26         NULL,                   /* lookup */
  27         NULL,                   /* link */
  28         NULL,                   /* unlink */
  29         NULL,                   /* symlink */
  30         NULL,                   /* mkdir */
  31         NULL,                   /* rmdir */
  32         NULL,                   /* mknod */
  33         NULL,                   /* rename */
  34         proc_readlink,          /* readlink */
  35         proc_follow_link,       /* follow_link */
  36         NULL,                   /* bmap */
  37         NULL,                   /* truncate */
  38         NULL                    /* permission */
  39 };
  40 
  41 static int proc_follow_link(struct inode * dir, struct inode * inode,
     /*  */
  42         int flag, int mode, struct inode ** res_inode)
  43 {
  44         unsigned int pid, ino;
  45         struct task_struct * p;
  46         int i;
  47 
  48         *res_inode = NULL;
  49         if (dir)
  50                 iput(dir);
  51         if (!inode)
  52                 return -ENOENT;
  53         ino = inode->i_ino;
  54         pid = ino >> 16;
  55         ino &= 0x0000ffff;
  56         iput(inode);
  57         for (i = 0 ; i < NR_TASKS ; i++)
  58                 if ((p = task[i]) && p->pid == pid)
  59                         break;
  60         if (i >= NR_TASKS)
  61                 return -ENOENT;
  62         inode = NULL;
  63         switch (ino) {
  64                 case 4:
  65                         inode = p->pwd;
  66                         break;
  67                 case 5:
  68                         inode = p->root;
  69                         break;
  70                 case 6:
  71                         inode = p->executable;
  72                         break;
  73                 default:
  74                         switch (ino >> 8) {
  75                                 case 1:
  76                                         ino &= 0xff;
  77                                         if (ino < NR_OPEN && p->filp[ino])
  78                                                 inode = p->filp[ino]->f_inode;
  79                                         break;
  80                                 case 2:
  81                                         ino &= 0xff;
  82                                         { int j = ino;
  83                                           struct vm_area_struct * mpnt;
  84                                           for(mpnt = p->mmap; mpnt && j >= 0;
  85                                               mpnt = mpnt->vm_next){
  86                                             if(mpnt->vm_inode) {
  87                                               if(j == 0) {
  88                                                 inode = mpnt->vm_inode;
  89                                                 break;
  90                                               };
  91                                               j--;
  92                                             }
  93                                           }
  94                                         };
  95                         }
  96         }
  97         if (!inode)
  98                 return -ENOENT;
  99         *res_inode = inode;
 100         inode->i_count++;
 101         return 0;
 102 }
 103 
 104 static int proc_readlink(struct inode * inode, char * buffer, int buflen)
     /*  */
 105 {
 106         int i;
 107         unsigned int dev,ino;
 108         char buf[64];
 109 
 110         i = proc_follow_link(NULL, inode, 0, 0, &inode);
 111         if (i)
 112                 return i;
 113         if (!inode)
 114                 return -EIO;
 115         dev = inode->i_dev;
 116         ino = inode->i_ino;
 117         iput(inode);
 118         i = sprintf(buf,"[%04x]:%u", dev, ino);
 119         if (buflen > i)
 120                 buflen = i;
 121         i = 0;
 122         while (i < buflen)
 123                 put_fs_byte(buf[i++],buffer++);
 124         return i;
 125 }
/* */
root/fs/proc/link.c

DEFINITIONS
