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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 | /* * linux/fs/proc/link.c * * Copyright (C) 1991, 1992 Linus Torvalds * * /proc link-file handling code */ #include <asm/segment.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/proc_fs.h> #include <linux/stat.h> static int proc_readlink(struct inode *, char *, int); static int proc_follow_link(struct inode *, struct inode *, int, int, struct inode **); /* * PLAN9_SEMANTICS won't work any more: it used an ugly hack that broke * when the files[] array was updated only after the open code */ #undef PLAN9_SEMANTICS /* * 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, /* select - default */ NULL, /* ioctl - default */ NULL, /* mmap */ NULL, /* very special open code */ 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 */ NULL /* permission */ }; static int proc_follow_link(struct inode * dir, struct inode * inode, int flag, int mode, struct inode ** res_inode) { unsigned int pid, ino; struct task_struct * p; struct inode * new_inode; int i, error; *res_inode = NULL; if (dir) iput(dir); if (!inode) return -ENOENT; if ((error = permission(inode, MAY_EXEC)) != 0){ iput(inode); return error; } ino = inode->i_ino; pid = ino >> 16; ino &= 0x0000ffff; for (i = 0 ; i < NR_TASKS ; i++) if ((p = task[i]) && p->pid == pid) break; if (i >= NR_TASKS) { iput(inode); return -ENOENT; } new_inode = NULL; switch (ino) { case PROC_PID_CWD: if (!p->fs) break; new_inode = p->fs->pwd; break; case PROC_PID_ROOT: if (!p->fs) break; new_inode = p->fs->root; break; case PROC_PID_EXE: { struct vm_area_struct * vma; if (!p->mm) break; vma = p->mm->mmap; while (vma) { if (vma->vm_flags & VM_EXECUTABLE) { new_inode = vma->vm_inode; break; } vma = vma->vm_next; } break; } default: switch (ino >> 8) { case PROC_PID_FD_DIR: if (!p->files) break; ino &= 0xff; if (ino < NR_OPEN && p->files && p->files->fd[ino]) { new_inode = p->files->fd[ino]->f_inode; } break; } } iput(inode); if (!new_inode) return -ENOENT; *res_inode = new_inode; new_inode->i_count++; return 0; } static int proc_readlink(struct inode * inode, char * buffer, int buflen) { int i; unsigned int dev,ino; char buf[64]; if (!S_ISLNK(inode->i_mode)) { iput(inode); return -EINVAL; } i = proc_follow_link(NULL, inode, 0, 0, &inode); if (i) return i; if (!inode) return -EIO; dev = kdev_t_to_nr(inode->i_dev); ino = inode->i_ino; iput(inode); i = sprintf(buf,"[%04x]:%u", dev, ino); if (buflen > i) buflen = i; i = 0; while (i < buflen) put_user(buf[i++],buffer++); return i; } |