1 /* Tests for opening a file without destroying an old file with the same name.
2 
3    Copyright (C) 2020-2021 Free Software Foundation, Inc.
4 
5    This program is free software: you can redistribute it and/or modify
6    it under the terms of the GNU General Public License as published by
7    the Free Software Foundation; either version 3 of the License, or
8    (at your option) any later version.
9 
10    This program is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13    GNU General Public License for more details.
14 
15    You should have received a copy of the GNU General Public License
16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
17 
18 /* Written by Bruno Haible, 2020.  */
19 
20 static void
test_open_supersede(bool supersede_if_exists,bool supersede_if_does_not_exist)21 test_open_supersede (bool supersede_if_exists, bool supersede_if_does_not_exist)
22 {
23   char xtemplate[] = "gnulibtestXXXXXX";
24   char *dir = mkdtemp (xtemplate);
25   char *filename = file_name_concat (dir, "test.mo", NULL);
26   struct stat statbuf;
27 
28   /* Test the case that the file does not yet exist.  */
29   {
30     ASSERT (stat (filename, &statbuf) < 0);
31 
32     struct supersede_final_action action;
33     int fd = open_supersede (filename, O_RDWR | O_BINARY | O_TRUNC, 0666,
34                              supersede_if_exists, supersede_if_does_not_exist,
35                              &action);
36     ASSERT (fd >= 0);
37     ASSERT (write (fd, "Hello world\n", 12) == 12);
38     if (supersede_if_does_not_exist)
39       ASSERT (stat (filename, &statbuf) < 0);
40     else
41       ASSERT (stat (filename, &statbuf) == 0);
42     ASSERT (close_supersede (fd, &action) == 0);
43 
44     ASSERT (stat (filename, &statbuf) == 0);
45 
46     size_t file_size;
47     char *file_contents = read_file (filename, RF_BINARY, &file_size);
48     ASSERT (file_size == 12);
49     ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
50   }
51 
52   /* Test the case that the file exists and is a regular file.  */
53   {
54     ASSERT (stat (filename, &statbuf) == 0);
55     dev_t orig_dev = statbuf.st_dev;
56     ino_t orig_ino = statbuf.st_ino;
57 
58     struct supersede_final_action action;
59     int fd = open_supersede (filename, O_RDWR | O_BINARY | O_TRUNC, 0666,
60                              supersede_if_exists, supersede_if_does_not_exist,
61                              &action);
62     ASSERT (fd >= 0);
63     ASSERT (write (fd, "Foobar\n", 7) == 7);
64     ASSERT (stat (filename, &statbuf) == 0);
65     {
66       size_t file_size;
67       char *file_contents = read_file (filename, RF_BINARY, &file_size);
68       if (supersede_if_exists)
69         {
70           ASSERT (file_size == 12);
71           ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
72         }
73       else
74         {
75           ASSERT (file_size == 7);
76           ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
77         }
78     }
79     ASSERT (close_supersede (fd, &action) == 0);
80 
81     ASSERT (stat (filename, &statbuf) == 0);
82 
83     size_t file_size;
84     char *file_contents = read_file (filename, RF_BINARY, &file_size);
85     ASSERT (file_size == 7);
86     ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
87 
88     if (supersede_if_exists)
89       {
90         /* Verify that the file now has a different inode number, on the same
91            device.  */
92 #if !(defined _WIN32 && !defined __CYGWIN__)
93         /* Note: On Linux/mips, statbuf.st_dev is smaller than a dev_t!  */
94         dev_t new_dev = statbuf.st_dev;
95         ASSERT (memcmp (&orig_dev, &new_dev, sizeof (dev_t)) == 0);
96         ASSERT (memcmp (&orig_ino, &statbuf.st_ino, sizeof (ino_t)) != 0);
97 #endif
98       }
99   }
100 
101   /* Test the case that the file exists and is a character device.  */
102   {
103     ASSERT (stat (DEV_NULL, &statbuf) == 0);
104 
105     struct supersede_final_action action;
106     int fd = open_supersede (DEV_NULL, O_RDWR | O_BINARY | O_TRUNC, 0666,
107                              supersede_if_exists, supersede_if_does_not_exist,
108                              &action);
109     ASSERT (fd >= 0);
110     ASSERT (write (fd, "Foobar\n", 7) == 7);
111     ASSERT (stat (DEV_NULL, &statbuf) == 0);
112     ASSERT (close_supersede (fd, &action) == 0);
113 
114     ASSERT (stat (DEV_NULL, &statbuf) == 0);
115   }
116 
117   /* Test the case that the file is a symbolic link to an existing regular
118      file.  */
119   {
120     const char *linkname = "link1";
121     unlink (linkname);
122     if (symlink (filename, linkname) >= 0)
123       {
124         ASSERT (stat (linkname, &statbuf) == 0);
125         dev_t orig_dev = statbuf.st_dev;
126         ino_t orig_ino = statbuf.st_ino;
127 
128         struct supersede_final_action action;
129         int fd =
130           open_supersede (linkname, O_RDWR | O_BINARY | O_TRUNC, 0666,
131                           supersede_if_exists, supersede_if_does_not_exist,
132                           &action);
133         ASSERT (fd >= 0);
134         ASSERT (write (fd, "New\n", 4) == 4);
135         ASSERT (stat (linkname, &statbuf) == 0);
136         {
137           size_t file_size;
138           char *file_contents = read_file (linkname, RF_BINARY, &file_size);
139           if (supersede_if_exists)
140             {
141               ASSERT (file_size == 7);
142               ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
143             }
144           else
145             {
146               ASSERT (file_size == 4);
147               ASSERT (memcmp (file_contents, "New\n", 4) == 0);
148             }
149         }
150         ASSERT (close_supersede (fd, &action) == 0);
151 
152         ASSERT (stat (linkname, &statbuf) == 0);
153 
154         size_t file_size;
155         char *file_contents = read_file (linkname, RF_BINARY, &file_size);
156         ASSERT (file_size == 4);
157         ASSERT (memcmp (file_contents, "New\n", 4) == 0);
158 
159         if (supersede_if_exists)
160           {
161             /* Verify that the file now has a different inode number, on the
162                same device.  */
163 #if !(defined _WIN32 && !defined __CYGWIN__)
164             /* Note: On Linux/mips, statbuf.st_dev is smaller than a dev_t!  */
165             dev_t new_dev = statbuf.st_dev;
166             ASSERT (memcmp (&orig_dev, &new_dev, sizeof (dev_t)) == 0);
167             ASSERT (memcmp (&orig_ino, &statbuf.st_ino, sizeof (ino_t)) != 0);
168 #endif
169           }
170 
171         /* Clean up.  */
172         unlink (linkname);
173       }
174   }
175 
176   /* Test the case that the file is a symbolic link to an existing character
177      device.  */
178   {
179     const char *linkname = "link2";
180     unlink (linkname);
181     if (symlink (DEV_NULL, linkname) >= 0)
182       {
183         ASSERT (stat (linkname, &statbuf) == 0);
184 
185         struct supersede_final_action action;
186         int fd =
187           open_supersede (linkname, O_RDWR | O_BINARY | O_TRUNC, 0666,
188                           supersede_if_exists, supersede_if_does_not_exist,
189                           &action);
190         ASSERT (fd >= 0);
191         ASSERT (write (fd, "New\n", 4) == 4);
192         ASSERT (stat (linkname, &statbuf) == 0);
193         ASSERT (close_supersede (fd, &action) == 0);
194 
195         ASSERT (stat (linkname, &statbuf) == 0);
196 
197         /* Clean up.  */
198         unlink (linkname);
199       }
200   }
201 
202   /* Clean up.  */
203   unlink (filename);
204 
205   /* Test the case that the file is a symbolic link to a nonexistent file in an
206      existing directory.  */
207   {
208     const char *linkname = "link3";
209     unlink (linkname);
210     if (symlink (filename, linkname) >= 0)
211       {
212         ASSERT (stat (linkname, &statbuf) < 0);
213 
214         struct supersede_final_action action;
215         int fd =
216           open_supersede (linkname, O_RDWR | O_BINARY | O_TRUNC, 0666,
217                           supersede_if_exists, supersede_if_does_not_exist,
218                           &action);
219         ASSERT (fd >= 0);
220         ASSERT (write (fd, "Hello world\n", 12) == 12);
221         if (supersede_if_does_not_exist)
222           ASSERT (stat (linkname, &statbuf) < 0);
223         else
224           ASSERT (stat (linkname, &statbuf) == 0);
225         ASSERT (close_supersede (fd, &action) == 0);
226 
227         ASSERT (stat (linkname, &statbuf) == 0);
228 
229         size_t file_size;
230         char *file_contents = read_file (linkname, RF_BINARY, &file_size);
231         ASSERT (file_size == 12);
232         ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
233 
234         /* Clean up.  */
235         unlink (linkname);
236       }
237   }
238 
239   /* Test the case that the file is a symbolic link to a nonexistent file in a
240      nonexistent directory.  */
241   {
242     const char *linkname = "link4";
243     unlink (linkname);
244     if (symlink ("/nonexistent/gnulibtest8237/24715863701440", linkname) >= 0)
245       {
246         ASSERT (stat (linkname, &statbuf) < 0);
247 
248         struct supersede_final_action action;
249         int fd =
250           open_supersede (linkname, O_RDWR | O_BINARY | O_TRUNC, 0666,
251                           supersede_if_exists, supersede_if_does_not_exist,
252                           &action);
253         ASSERT (fd < 0);
254         ASSERT (errno == ENOENT);
255 
256         ASSERT (stat (linkname, &statbuf) < 0);
257 
258         /* Clean up.  */
259         unlink (linkname);
260       }
261   }
262 
263   /* Clean up.  */
264   unlink (filename);
265   rmdir (dir);
266 }
267