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path: root/fs/readdir.c (plain)
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1/*
2 * linux/fs/readdir.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 */
6
7#include <linux/stddef.h>
8#include <linux/kernel.h>
9#include <linux/export.h>
10#include <linux/time.h>
11#include <linux/mm.h>
12#include <linux/errno.h>
13#include <linux/stat.h>
14#include <linux/file.h>
15#include <linux/fs.h>
16#include <linux/fsnotify.h>
17#include <linux/dirent.h>
18#include <linux/security.h>
19#include <linux/syscalls.h>
20#include <linux/unistd.h>
21
22#include <asm/uaccess.h>
23
24int iterate_dir(struct file *file, struct dir_context *ctx)
25{
26 struct inode *inode = file_inode(file);
27 bool shared = false;
28 int res = -ENOTDIR;
29 if (file->f_op->iterate_shared)
30 shared = true;
31 else if (!file->f_op->iterate)
32 goto out;
33
34 res = security_file_permission(file, MAY_READ);
35 if (res)
36 goto out;
37
38 if (shared) {
39 inode_lock_shared(inode);
40 } else {
41 res = down_write_killable(&inode->i_rwsem);
42 if (res)
43 goto out;
44 }
45
46 res = -ENOENT;
47 if (!IS_DEADDIR(inode)) {
48 ctx->pos = file->f_pos;
49 if (shared)
50 res = file->f_op->iterate_shared(file, ctx);
51 else
52 res = file->f_op->iterate(file, ctx);
53 file->f_pos = ctx->pos;
54 fsnotify_access(file);
55 file_accessed(file);
56 }
57 if (shared)
58 inode_unlock_shared(inode);
59 else
60 inode_unlock(inode);
61out:
62 return res;
63}
64EXPORT_SYMBOL(iterate_dir);
65
66/*
67 * Traditional linux readdir() handling..
68 *
69 * "count=1" is a special case, meaning that the buffer is one
70 * dirent-structure in size and that the code can't handle more
71 * anyway. Thus the special "fillonedir()" function for that
72 * case (the low-level handlers don't need to care about this).
73 */
74
75#ifdef __ARCH_WANT_OLD_READDIR
76
77struct old_linux_dirent {
78 unsigned long d_ino;
79 unsigned long d_offset;
80 unsigned short d_namlen;
81 char d_name[1];
82};
83
84struct readdir_callback {
85 struct dir_context ctx;
86 struct old_linux_dirent __user * dirent;
87 int result;
88};
89
90static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
91 loff_t offset, u64 ino, unsigned int d_type)
92{
93 struct readdir_callback *buf =
94 container_of(ctx, struct readdir_callback, ctx);
95 struct old_linux_dirent __user * dirent;
96 unsigned long d_ino;
97
98 if (buf->result)
99 return -EINVAL;
100 d_ino = ino;
101 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
102 buf->result = -EOVERFLOW;
103 return -EOVERFLOW;
104 }
105 buf->result++;
106 dirent = buf->dirent;
107 if (!access_ok(VERIFY_WRITE, dirent,
108 (unsigned long)(dirent->d_name + namlen + 1) -
109 (unsigned long)dirent))
110 goto efault;
111 if ( __put_user(d_ino, &dirent->d_ino) ||
112 __put_user(offset, &dirent->d_offset) ||
113 __put_user(namlen, &dirent->d_namlen) ||
114 __copy_to_user(dirent->d_name, name, namlen) ||
115 __put_user(0, dirent->d_name + namlen))
116 goto efault;
117 return 0;
118efault:
119 buf->result = -EFAULT;
120 return -EFAULT;
121}
122
123SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
124 struct old_linux_dirent __user *, dirent, unsigned int, count)
125{
126 int error;
127 struct fd f = fdget_pos(fd);
128 struct readdir_callback buf = {
129 .ctx.actor = fillonedir,
130 .dirent = dirent
131 };
132
133 if (!f.file)
134 return -EBADF;
135
136 error = iterate_dir(f.file, &buf.ctx);
137 if (buf.result)
138 error = buf.result;
139
140 fdput_pos(f);
141 return error;
142}
143
144#endif /* __ARCH_WANT_OLD_READDIR */
145
146/*
147 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
148 * interface.
149 */
150struct linux_dirent {
151 unsigned long d_ino;
152 unsigned long d_off;
153 unsigned short d_reclen;
154 char d_name[1];
155};
156
157struct getdents_callback {
158 struct dir_context ctx;
159 struct linux_dirent __user * current_dir;
160 struct linux_dirent __user * previous;
161 int count;
162 int error;
163};
164
165static int filldir(struct dir_context *ctx, const char *name, int namlen,
166 loff_t offset, u64 ino, unsigned int d_type)
167{
168 struct linux_dirent __user * dirent;
169 struct getdents_callback *buf =
170 container_of(ctx, struct getdents_callback, ctx);
171 unsigned long d_ino;
172 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
173 sizeof(long));
174
175 buf->error = -EINVAL; /* only used if we fail.. */
176 if (reclen > buf->count)
177 return -EINVAL;
178 d_ino = ino;
179 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
180 buf->error = -EOVERFLOW;
181 return -EOVERFLOW;
182 }
183 dirent = buf->previous;
184 if (dirent) {
185 if (signal_pending(current))
186 return -EINTR;
187 if (__put_user(offset, &dirent->d_off))
188 goto efault;
189 }
190 dirent = buf->current_dir;
191 if (__put_user(d_ino, &dirent->d_ino))
192 goto efault;
193 if (__put_user(reclen, &dirent->d_reclen))
194 goto efault;
195 if (copy_to_user(dirent->d_name, name, namlen))
196 goto efault;
197 if (__put_user(0, dirent->d_name + namlen))
198 goto efault;
199 if (__put_user(d_type, (char __user *) dirent + reclen - 1))
200 goto efault;
201 buf->previous = dirent;
202 dirent = (void __user *)dirent + reclen;
203 buf->current_dir = dirent;
204 buf->count -= reclen;
205 return 0;
206efault:
207 buf->error = -EFAULT;
208 return -EFAULT;
209}
210
211SYSCALL_DEFINE3(getdents, unsigned int, fd,
212 struct linux_dirent __user *, dirent, unsigned int, count)
213{
214 struct fd f;
215 struct linux_dirent __user * lastdirent;
216 struct getdents_callback buf = {
217 .ctx.actor = filldir,
218 .count = count,
219 .current_dir = dirent
220 };
221 int error;
222
223 if (!access_ok(VERIFY_WRITE, dirent, count))
224 return -EFAULT;
225
226 f = fdget_pos(fd);
227 if (!f.file)
228 return -EBADF;
229
230 error = iterate_dir(f.file, &buf.ctx);
231 if (error >= 0)
232 error = buf.error;
233 lastdirent = buf.previous;
234 if (lastdirent) {
235 if (put_user(buf.ctx.pos, &lastdirent->d_off))
236 error = -EFAULT;
237 else
238 error = count - buf.count;
239 }
240 fdput_pos(f);
241 return error;
242}
243
244struct getdents_callback64 {
245 struct dir_context ctx;
246 struct linux_dirent64 __user * current_dir;
247 struct linux_dirent64 __user * previous;
248 int count;
249 int error;
250};
251
252static int filldir64(struct dir_context *ctx, const char *name, int namlen,
253 loff_t offset, u64 ino, unsigned int d_type)
254{
255 struct linux_dirent64 __user *dirent;
256 struct getdents_callback64 *buf =
257 container_of(ctx, struct getdents_callback64, ctx);
258 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
259 sizeof(u64));
260
261 buf->error = -EINVAL; /* only used if we fail.. */
262 if (reclen > buf->count)
263 return -EINVAL;
264 dirent = buf->previous;
265 if (dirent) {
266 if (signal_pending(current))
267 return -EINTR;
268 if (__put_user(offset, &dirent->d_off))
269 goto efault;
270 }
271 dirent = buf->current_dir;
272 if (__put_user(ino, &dirent->d_ino))
273 goto efault;
274 if (__put_user(0, &dirent->d_off))
275 goto efault;
276 if (__put_user(reclen, &dirent->d_reclen))
277 goto efault;
278 if (__put_user(d_type, &dirent->d_type))
279 goto efault;
280 if (copy_to_user(dirent->d_name, name, namlen))
281 goto efault;
282 if (__put_user(0, dirent->d_name + namlen))
283 goto efault;
284 buf->previous = dirent;
285 dirent = (void __user *)dirent + reclen;
286 buf->current_dir = dirent;
287 buf->count -= reclen;
288 return 0;
289efault:
290 buf->error = -EFAULT;
291 return -EFAULT;
292}
293
294SYSCALL_DEFINE3(getdents64, unsigned int, fd,
295 struct linux_dirent64 __user *, dirent, unsigned int, count)
296{
297 struct fd f;
298 struct linux_dirent64 __user * lastdirent;
299 struct getdents_callback64 buf = {
300 .ctx.actor = filldir64,
301 .count = count,
302 .current_dir = dirent
303 };
304 int error;
305
306 if (!access_ok(VERIFY_WRITE, dirent, count))
307 return -EFAULT;
308
309 f = fdget_pos(fd);
310 if (!f.file)
311 return -EBADF;
312
313 error = iterate_dir(f.file, &buf.ctx);
314 if (error >= 0)
315 error = buf.error;
316 lastdirent = buf.previous;
317 if (lastdirent) {
318 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
319 if (__put_user(d_off, &lastdirent->d_off))
320 error = -EFAULT;
321 else
322 error = count - buf.count;
323 }
324 fdput_pos(f);
325 return error;
326}
327
generated by cgit at 2024-05-18 11:48:50 (GMT)