1 /* Test of fcntl(2).
2    Copyright (C) 2009-2020 Free Software Foundation, Inc.
3 
4    This program is free software: you can redistribute it and/or modify
5    it under the terms of the GNU General Public License as published by
6    the Free Software Foundation; either version 3 of the License, or
7    (at your option) any later version.
8 
9    This program is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12    GNU General Public License for more details.
13 
14    You should have received a copy of the GNU General Public License
15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
16 
17 /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
18 
19 #include <config.h>
20 
21 /* Specification.  */
22 #include <fcntl.h>
23 
24 #include "signature.h"
25 SIGNATURE_CHECK (fcntl, int, (int, int, ...));
26 
27 /* Helpers.  */
28 #include <errno.h>
29 #include <stdarg.h>
30 #include <stdbool.h>
31 #include <unistd.h>
32 
33 #if defined _WIN32 && ! defined __CYGWIN__
34 /* Get declarations of the native Windows API functions.  */
35 # define WIN32_LEAN_AND_MEAN
36 # include <windows.h>
37 /* Get _get_osfhandle.  */
38 # if GNULIB_MSVC_NOTHROW
39 #  include "msvc-nothrow.h"
40 # else
41 #  include <io.h>
42 # endif
43 #endif
44 
45 #include "binary-io.h"
46 #include "macros.h"
47 
48 #if !O_BINARY
49 # define setmode(f,m) zero ()
zero(void)50 static int zero (void) { return 0; }
51 #endif
52 
53 /* Return true if FD is open.  */
54 static bool
is_open(int fd)55 is_open (int fd)
56 {
57 #if defined _WIN32 && ! defined __CYGWIN__
58   /* On native Windows, the initial state of unassigned standard file
59      descriptors is that they are open but point to an
60      INVALID_HANDLE_VALUE, and there is no fcntl.  */
61   return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
62 #else
63 # ifndef F_GETFL
64 #  error Please port fcntl to your platform
65 # endif
66   return 0 <= fcntl (fd, F_GETFL);
67 #endif
68 }
69 
70 /* Return true if FD is open and inheritable across exec/spawn.  */
71 static bool
is_inheritable(int fd)72 is_inheritable (int fd)
73 {
74 #if defined _WIN32 && ! defined __CYGWIN__
75   /* On native Windows, the initial state of unassigned standard file
76      descriptors is that they are open but point to an
77      INVALID_HANDLE_VALUE, and there is no fcntl.  */
78   HANDLE h = (HANDLE) _get_osfhandle (fd);
79   DWORD flags;
80   if (h == INVALID_HANDLE_VALUE || GetHandleInformation (h, &flags) == 0)
81     return false;
82   return (flags & HANDLE_FLAG_INHERIT) != 0;
83 #else
84 # ifndef F_GETFD
85 #  error Please port fcntl to your platform
86 # endif
87   int i = fcntl (fd, F_GETFD);
88   return 0 <= i && (i & FD_CLOEXEC) == 0;
89 #endif
90 }
91 
92 /* Return non-zero if FD is open in the given MODE, which is either
93    O_TEXT or O_BINARY.  */
94 static bool
is_mode(int fd,int mode)95 is_mode (int fd, int mode)
96 {
97   int value = setmode (fd, O_BINARY);
98   setmode (fd, value);
99   return mode == value;
100 }
101 
102 /* Since native fcntl can have more supported operations than our
103    replacement is aware of, and since various operations assign
104    different types to the vararg argument, a wrapper around fcntl must
105    be able to pass a vararg of unknown type on through to the original
106    fcntl.  Make sure that this works properly: func1 behaves like the
107    original fcntl interpreting the vararg as an int or a pointer to a
108    struct, and func2 behaves like rpl_fcntl that doesn't know what
109    type to forward.  */
110 struct dummy_struct
111 {
112   long filler;
113   int value;
114 };
115 static int
func1(int a,...)116 func1 (int a, ...)
117 {
118   va_list arg;
119   int i;
120   va_start (arg, a);
121   if (a < 4)
122     i = va_arg (arg, int);
123   else
124     {
125       struct dummy_struct *s = va_arg (arg, struct dummy_struct *);
126       i = s->value;
127     }
128   va_end (arg);
129   return i;
130 }
131 static int
func2(int a,...)132 func2 (int a, ...)
133 {
134   va_list arg;
135   void *p;
136   va_start (arg, a);
137   p = va_arg (arg, void *);
138   va_end (arg);
139   return func1 (a, p);
140 }
141 
142 /* Ensure that all supported fcntl actions are distinct, and
143    usable in preprocessor expressions.  */
144 static void
check_flags(void)145 check_flags (void)
146 {
147   switch (0)
148     {
149     case F_DUPFD:
150 #if F_DUPFD
151 #endif
152 
153     case F_DUPFD_CLOEXEC:
154 #if F_DUPFD_CLOEXEC
155 #endif
156 
157     case F_GETFD:
158 #if F_GETFD
159 #endif
160 
161 #ifdef F_SETFD
162     case F_SETFD:
163 # if F_SETFD
164 # endif
165 #endif
166 
167 #ifdef F_GETFL
168     case F_GETFL:
169 # if F_GETFL
170 # endif
171 #endif
172 
173 #ifdef F_SETFL
174     case F_SETFL:
175 # if F_SETFL
176 # endif
177 #endif
178 
179 #ifdef F_GETOWN
180     case F_GETOWN:
181 # if F_GETOWN
182 # endif
183 #endif
184 
185 #ifdef F_SETOWN
186     case F_SETOWN:
187 # if F_SETOWN
188 # endif
189 #endif
190 
191 #ifdef F_GETLK
192     case F_GETLK:
193 # if F_GETLK
194 # endif
195 #endif
196 
197 #ifdef F_SETLK
198     case F_SETLK:
199 # if F_SETLK
200 # endif
201 #endif
202 
203 #ifdef F_SETLKW
204     case F_SETLKW:
205 # if F_SETLKW
206 # endif
207 #endif
208 
209       ;
210     }
211 }
212 
213 int
main(void)214 main (void)
215 {
216   const char *file = "test-fcntl.tmp";
217   int fd;
218   int bad_fd = getdtablesize ();
219 
220   /* Sanity check that rpl_fcntl is likely to work.  */
221   ASSERT (func2 (1, 2) == 2);
222   ASSERT (func2 (2, -2) == -2);
223   ASSERT (func2 (3, 0x80000000) == 0x80000000);
224   {
225     struct dummy_struct s = { 0L, 4 };
226     ASSERT (func2 (4, &s) == 4);
227   }
228   check_flags ();
229 
230   /* Assume std descriptors were provided by invoker, and ignore fds
231      that might have been inherited.  */
232   fd = creat (file, 0600);
233   ASSERT (STDERR_FILENO < fd);
234   close (fd + 1);
235   close (fd + 2);
236 
237   /* For F_DUPFD*, the source must be valid.  */
238   errno = 0;
239   ASSERT (fcntl (-1, F_DUPFD, 0) == -1);
240   ASSERT (errno == EBADF);
241   errno = 0;
242   ASSERT (fcntl (fd + 1, F_DUPFD, 0) == -1);
243   ASSERT (errno == EBADF);
244   errno = 0;
245   ASSERT (fcntl (bad_fd, F_DUPFD, 0) == -1);
246   ASSERT (errno == EBADF);
247   errno = 0;
248   ASSERT (fcntl (-1, F_DUPFD_CLOEXEC, 0) == -1);
249   ASSERT (errno == EBADF);
250   errno = 0;
251   ASSERT (fcntl (fd + 1, F_DUPFD_CLOEXEC, 0) == -1);
252   ASSERT (errno == EBADF);
253   errno = 0;
254   ASSERT (fcntl (bad_fd, F_DUPFD_CLOEXEC, 0) == -1);
255   ASSERT (errno == EBADF);
256 
257   /* For F_DUPFD*, the destination must be valid.  */
258   errno = 0;
259   ASSERT (fcntl (fd, F_DUPFD, -1) == -1);
260   ASSERT (errno == EINVAL);
261   errno = 0;
262   ASSERT (fcntl (fd, F_DUPFD, bad_fd) == -1);
263   ASSERT (errno == EINVAL);
264   errno = 0;
265   ASSERT (fcntl (fd, F_DUPFD_CLOEXEC, -1) == -1);
266   ASSERT (errno == EINVAL);
267   errno = 0;
268   ASSERT (fcntl (fd, F_DUPFD_CLOEXEC, bad_fd) == -1);
269   ASSERT (errno == EINVAL
270           || errno == EMFILE /* WSL */);
271 
272   /* For F_DUPFD*, check for correct inheritance, as well as
273      preservation of text vs. binary.  */
274   setmode (fd, O_BINARY);
275   ASSERT (is_open (fd));
276   ASSERT (!is_open (fd + 1));
277   ASSERT (!is_open (fd + 2));
278   ASSERT (is_inheritable (fd));
279   ASSERT (is_mode (fd, O_BINARY));
280 
281   ASSERT (fcntl (fd, F_DUPFD, fd) == fd + 1);
282   ASSERT (is_open (fd));
283   ASSERT (is_open (fd + 1));
284   ASSERT (!is_open (fd + 2));
285   ASSERT (is_inheritable (fd + 1));
286   ASSERT (is_mode (fd, O_BINARY));
287   ASSERT (is_mode (fd + 1, O_BINARY));
288   ASSERT (close (fd + 1) == 0);
289 
290   ASSERT (fcntl (fd, F_DUPFD_CLOEXEC, fd + 2) == fd + 2);
291   ASSERT (is_open (fd));
292   ASSERT (!is_open (fd + 1));
293   ASSERT (is_open (fd + 2));
294   ASSERT (is_inheritable (fd));
295   ASSERT (!is_inheritable (fd + 2));
296   ASSERT (is_mode (fd, O_BINARY));
297   ASSERT (is_mode (fd + 2, O_BINARY));
298   ASSERT (close (fd) == 0);
299 
300   setmode (fd + 2, O_TEXT);
301   ASSERT (fcntl (fd + 2, F_DUPFD, fd + 1) == fd + 1);
302   ASSERT (!is_open (fd));
303   ASSERT (is_open (fd + 1));
304   ASSERT (is_open (fd + 2));
305   ASSERT (is_inheritable (fd + 1));
306   ASSERT (!is_inheritable (fd + 2));
307   ASSERT (is_mode (fd + 1, O_TEXT));
308   ASSERT (is_mode (fd + 2, O_TEXT));
309   ASSERT (close (fd + 1) == 0);
310 
311   ASSERT (fcntl (fd + 2, F_DUPFD_CLOEXEC, 0) == fd);
312   ASSERT (is_open (fd));
313   ASSERT (!is_open (fd + 1));
314   ASSERT (is_open (fd + 2));
315   ASSERT (!is_inheritable (fd));
316   ASSERT (!is_inheritable (fd + 2));
317   ASSERT (is_mode (fd, O_TEXT));
318   ASSERT (is_mode (fd + 2, O_TEXT));
319   ASSERT (close (fd + 2) == 0);
320 
321   /* Test F_GETFD on invalid file descriptors.  */
322   errno = 0;
323   ASSERT (fcntl (-1, F_GETFD) == -1);
324   ASSERT (errno == EBADF);
325   errno = 0;
326   ASSERT (fcntl (fd + 1, F_GETFD) == -1);
327   ASSERT (errno == EBADF);
328   errno = 0;
329   ASSERT (fcntl (bad_fd, F_GETFD) == -1);
330   ASSERT (errno == EBADF);
331 
332   /* Test F_GETFD, the FD_CLOEXEC bit.  */
333   {
334     int result = fcntl (fd, F_GETFD);
335     ASSERT (0 <= result);
336     ASSERT ((result & FD_CLOEXEC) == FD_CLOEXEC);
337     ASSERT (dup (fd) == fd + 1);
338     result = fcntl (fd + 1, F_GETFD);
339     ASSERT (0 <= result);
340     ASSERT ((result & FD_CLOEXEC) == 0);
341     ASSERT (close (fd + 1) == 0);
342   }
343 
344 #ifdef F_SETFD
345   /* Test F_SETFD on invalid file descriptors.  */
346   errno = 0;
347   ASSERT (fcntl (-1, F_SETFD, 0) == -1);
348   ASSERT (errno == EBADF);
349   errno = 0;
350   ASSERT (fcntl (fd + 1, F_SETFD, 0) == -1);
351   ASSERT (errno == EBADF);
352   errno = 0;
353   ASSERT (fcntl (bad_fd, F_SETFD, 0) == -1);
354   ASSERT (errno == EBADF);
355 #endif
356 
357 #ifdef F_GETFL
358   /* Test F_GETFL on invalid file descriptors.  */
359   errno = 0;
360   ASSERT (fcntl (-1, F_GETFL) == -1);
361   ASSERT (errno == EBADF);
362   errno = 0;
363   ASSERT (fcntl (fd + 1, F_GETFL) == -1);
364   ASSERT (errno == EBADF);
365   errno = 0;
366   ASSERT (fcntl (bad_fd, F_GETFL) == -1);
367   ASSERT (errno == EBADF);
368 #endif
369 
370 #ifdef F_SETFL
371   /* Test F_SETFL on invalid file descriptors.  */
372   errno = 0;
373   ASSERT (fcntl (-1, F_SETFL, 0) == -1);
374   ASSERT (errno == EBADF);
375   errno = 0;
376   ASSERT (fcntl (fd + 1, F_SETFL, 0) == -1);
377   ASSERT (errno == EBADF);
378   errno = 0;
379   ASSERT (fcntl (bad_fd, F_SETFL, 0) == -1);
380   ASSERT (errno == EBADF);
381 #endif
382 
383 #ifdef F_GETOWN
384   /* Test F_GETOWN on invalid file descriptors.  */
385   errno = 0;
386   ASSERT (fcntl (-1, F_GETOWN) == -1);
387   ASSERT (errno == EBADF);
388   errno = 0;
389   ASSERT (fcntl (fd + 1, F_GETOWN) == -1);
390   ASSERT (errno == EBADF);
391   errno = 0;
392   ASSERT (fcntl (bad_fd, F_GETOWN) == -1);
393   ASSERT (errno == EBADF);
394 #endif
395 
396 #ifdef F_SETOWN
397   /* Test F_SETFL on invalid file descriptors.  */
398   errno = 0;
399   ASSERT (fcntl (-1, F_SETOWN, 0) == -1);
400   ASSERT (errno == EBADF);
401   errno = 0;
402   ASSERT (fcntl (fd + 1, F_SETOWN, 0) == -1);
403   ASSERT (errno == EBADF);
404   errno = 0;
405   ASSERT (fcntl (bad_fd, F_SETOWN, 0) == -1);
406   ASSERT (errno == EBADF);
407 #endif
408 
409   /* Cleanup.  */
410   ASSERT (close (fd) == 0);
411   ASSERT (unlink (file) == 0);
412 
413   return 0;
414 }
415