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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 | /* * linux/fs/proc/link.c * * Copyright (C) 1991, 1992 Linus Torvalds * * /proc link-file handling code */ #include <asm/uaccess.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/mm.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/proc_fs.h> #include <linux/stat.h> static int proc_readlink(struct dentry *, char *, int); static struct dentry * proc_follow_link(struct dentry *, struct dentry *, unsigned int); /* * links can't do much... */ static struct file_operations proc_fd_link_operations = { NULL, /* lseek - default */ NULL, /* read - bad */ NULL, /* write - bad */ NULL, /* readdir - bad */ NULL, /* poll - default */ NULL, /* ioctl - default */ NULL, /* mmap */ NULL, /* very special open code */ NULL, /* flush */ NULL, /* no special release code */ NULL /* can't fsync */ }; struct inode_operations proc_link_inode_operations = { &proc_fd_link_operations,/* file-operations */ NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ proc_readlink, /* readlink */ proc_follow_link, /* follow_link */ NULL, /* readpage */ NULL, /* writepage */ NULL, /* bmap */ NULL, /* truncate */ proc_permission /* permission */ }; static struct dentry * proc_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow) { struct inode *inode = dentry->d_inode; struct task_struct *p; struct dentry * result; int ino, pid; int error; /* We don't need a base pointer in the /proc filesystem */ dput(base); error = permission(inode, MAY_EXEC); result = ERR_PTR(error); if (error) goto out; ino = inode->i_ino; pid = ino >> 16; ino &= 0x0000ffff; result = ERR_PTR(-ENOENT); read_lock(&tasklist_lock); p = find_task_by_pid(pid); if (!p) goto out_unlock; switch (ino) { case PROC_PID_CWD: if (!p->fs || !p->fs->pwd) goto out_unlock; result = p->fs->pwd; goto out_dget; case PROC_PID_ROOT: if (!p->fs || !p->fs->root) goto out_unlock; result = p->fs->root; goto out_dget; case PROC_PID_EXE: { struct vm_area_struct * vma; if (!p->mm) goto out_unlock; vma = p->mm->mmap; while (vma) { if ((vma->vm_flags & VM_EXECUTABLE) && vma->vm_file) { result = vma->vm_file->f_dentry; goto out_dget; } vma = vma->vm_next; } goto out_unlock; } default: if (ino & PROC_PID_FD_DIR) { struct file * file; ino &= 0x7fff; file = fcheck_task(p, ino); if (!file || !file->f_dentry) goto out_unlock; result = file->f_dentry; goto out_dget; } } out_dget: result = dget(result); out_unlock: read_unlock(&tasklist_lock); out: return result; } /* * This pretty-prints the pathname of a dentry, * clarifying sockets etc. */ static int do_proc_readlink(struct dentry *dentry, char * buffer, int buflen) { struct inode * inode; char * tmp = (char*)__get_free_page(GFP_KERNEL), *path, *pattern; int len; if(tmp==NULL) return -ENOMEM; /* Check for special dentries.. */ pattern = NULL; inode = dentry->d_inode; if (inode && dentry->d_parent == dentry) { if (S_ISSOCK(inode->i_mode)) pattern = "socket:[%lu]"; if (S_ISFIFO(inode->i_mode)) pattern = "pipe:[%lu]"; } if (pattern) { len = sprintf(tmp, pattern, inode->i_ino); path = tmp; } else { path = d_path(dentry, tmp, PAGE_SIZE); len = tmp + PAGE_SIZE - 1 - path; } if (len < buflen) buflen = len; dput(dentry); copy_to_user(buffer, path, buflen); free_page((unsigned long)tmp); return buflen; } static int proc_readlink(struct dentry * dentry, char * buffer, int buflen) { int error; dentry = proc_follow_link(dentry, NULL, 1); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { error = -ENOENT; if (dentry) { error = do_proc_readlink(dentry, buffer, buflen); } } return error; } |