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_fopen_supersede(bool supersede_if_exists,bool supersede_if_does_not_exist)21 test_fopen_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     FILE *fp =
34       fopen_supersede (filename, "wb",
35                        supersede_if_exists, supersede_if_does_not_exist,
36                        &action);
37     ASSERT (fp != NULL);
38     ASSERT (fwrite ("Hello world\n", 1, 12, fp) == 12 && fflush (fp) == 0);
39     if (supersede_if_does_not_exist)
40       ASSERT (stat (filename, &statbuf) < 0);
41     else
42       ASSERT (stat (filename, &statbuf) == 0);
43     ASSERT (fclose_supersede (fp, &action) == 0);
44 
45     ASSERT (stat (filename, &statbuf) == 0);
46 
47     size_t file_size;
48     char *file_contents = read_file (filename, RF_BINARY, &file_size);
49     ASSERT (file_size == 12);
50     ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
51   }
52 
53   /* Test the case that the file exists and is a regular file.  */
54   {
55     ASSERT (stat (filename, &statbuf) == 0);
56     dev_t orig_dev = statbuf.st_dev;
57     ino_t orig_ino = statbuf.st_ino;
58 
59     struct supersede_final_action action;
60     FILE *fp =
61       fopen_supersede (filename, "wb",
62                        supersede_if_exists, supersede_if_does_not_exist,
63                        &action);
64     ASSERT (fp != NULL);
65     ASSERT (fwrite ("Foobar\n", 1, 7, fp) == 7 && fflush (fp) == 0);
66     ASSERT (stat (filename, &statbuf) == 0);
67     {
68       size_t file_size;
69       char *file_contents = read_file (filename, RF_BINARY, &file_size);
70       if (supersede_if_exists)
71         {
72           ASSERT (file_size == 12);
73           ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
74         }
75       else
76         {
77           ASSERT (file_size == 7);
78           ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
79         }
80     }
81     ASSERT (fclose_supersede (fp, &action) == 0);
82 
83     ASSERT (stat (filename, &statbuf) == 0);
84 
85     size_t file_size;
86     char *file_contents = read_file (filename, RF_BINARY, &file_size);
87     ASSERT (file_size == 7);
88     ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
89 
90     if (supersede_if_exists)
91       {
92         /* Verify that the file now has a different inode number, on the same
93            device.  */
94 #if !(defined _WIN32 && !defined __CYGWIN__)
95         /* Note: On Linux/mips, statbuf.st_dev is smaller than a dev_t!  */
96         dev_t new_dev = statbuf.st_dev;
97         ASSERT (memcmp (&orig_dev, &new_dev, sizeof (dev_t)) == 0);
98         ASSERT (memcmp (&orig_ino, &statbuf.st_ino, sizeof (ino_t)) != 0);
99 #endif
100       }
101   }
102 
103   /* Test the case that the file exists and is a character device.  */
104   {
105     ASSERT (stat (DEV_NULL, &statbuf) == 0);
106 
107     struct supersede_final_action action;
108     FILE *fp =
109       fopen_supersede (DEV_NULL, "wb",
110                        supersede_if_exists, supersede_if_does_not_exist,
111                        &action);
112     ASSERT (fp != NULL);
113     ASSERT (fwrite ("Foobar\n", 1, 7, fp) == 7 && fflush (fp) == 0);
114     ASSERT (stat (DEV_NULL, &statbuf) == 0);
115     ASSERT (fclose_supersede (fp, &action) == 0);
116 
117     ASSERT (stat (DEV_NULL, &statbuf) == 0);
118   }
119 
120   /* Test the case that the file is a symbolic link to an existing regular
121      file.  */
122   {
123     const char *linkname = "link1";
124     unlink (linkname);
125     if (symlink (filename, linkname) >= 0)
126       {
127         ASSERT (stat (linkname, &statbuf) == 0);
128         dev_t orig_dev = statbuf.st_dev;
129         ino_t orig_ino = statbuf.st_ino;
130 
131         struct supersede_final_action action;
132         FILE *fp =
133           fopen_supersede (linkname, "wb",
134                            supersede_if_exists, supersede_if_does_not_exist,
135                            &action);
136         ASSERT (fp != NULL);
137         ASSERT (fwrite ("New\n", 1, 4, fp) == 4 && fflush (fp) == 0);
138         ASSERT (stat (linkname, &statbuf) == 0);
139         {
140           size_t file_size;
141           char *file_contents = read_file (linkname, RF_BINARY, &file_size);
142           if (supersede_if_exists)
143             {
144               ASSERT (file_size == 7);
145               ASSERT (memcmp (file_contents, "Foobar\n", 7) == 0);
146             }
147           else
148             {
149               ASSERT (file_size == 4);
150               ASSERT (memcmp (file_contents, "New\n", 4) == 0);
151             }
152         }
153         ASSERT (fclose_supersede (fp, &action) == 0);
154 
155         ASSERT (stat (linkname, &statbuf) == 0);
156 
157         size_t file_size;
158         char *file_contents = read_file (linkname, RF_BINARY, &file_size);
159         ASSERT (file_size == 4);
160         ASSERT (memcmp (file_contents, "New\n", 4) == 0);
161 
162         if (supersede_if_exists)
163           {
164             /* Verify that the file now has a different inode number, on the
165                same device.  */
166 #if !(defined _WIN32 && !defined __CYGWIN__)
167             /* Note: On Linux/mips, statbuf.st_dev is smaller than a dev_t!  */
168             dev_t new_dev = statbuf.st_dev;
169             ASSERT (memcmp (&orig_dev, &new_dev, sizeof (dev_t)) == 0);
170             ASSERT (memcmp (&orig_ino, &statbuf.st_ino, sizeof (ino_t)) != 0);
171 #endif
172           }
173 
174         /* Clean up.  */
175         unlink (linkname);
176       }
177   }
178 
179   /* Test the case that the file is a symbolic link to an existing character
180      device.  */
181   {
182     const char *linkname = "link2";
183     unlink (linkname);
184     if (symlink (DEV_NULL, linkname) >= 0)
185       {
186         ASSERT (stat (linkname, &statbuf) == 0);
187 
188         struct supersede_final_action action;
189         FILE *fp =
190           fopen_supersede (linkname, "wb",
191                            supersede_if_exists, supersede_if_does_not_exist,
192                            &action);
193         ASSERT (fp != NULL);
194         ASSERT (fwrite ("New\n", 1, 4, fp) == 4 && fflush (fp) == 0);
195         ASSERT (stat (linkname, &statbuf) == 0);
196         ASSERT (fclose_supersede (fp, &action) == 0);
197 
198         ASSERT (stat (linkname, &statbuf) == 0);
199 
200         /* Clean up.  */
201         unlink (linkname);
202       }
203   }
204 
205   /* Clean up.  */
206   unlink (filename);
207 
208   /* Test the case that the file is a symbolic link to a nonexistent file in an
209      existing directory.  */
210   {
211     const char *linkname = "link3";
212     unlink (linkname);
213     if (symlink (filename, linkname) >= 0)
214       {
215         ASSERT (stat (linkname, &statbuf) < 0);
216 
217         struct supersede_final_action action;
218         FILE *fp =
219           fopen_supersede (linkname, "wb",
220                            supersede_if_exists, supersede_if_does_not_exist,
221                            &action);
222         ASSERT (fp != NULL);
223         ASSERT (fwrite ("Hello world\n", 1, 12, fp) == 12 && fflush (fp) == 0);
224         if (supersede_if_does_not_exist)
225           ASSERT (stat (linkname, &statbuf) < 0);
226         else
227           ASSERT (stat (linkname, &statbuf) == 0);
228         ASSERT (fclose_supersede (fp, &action) == 0);
229 
230         ASSERT (stat (linkname, &statbuf) == 0);
231 
232         size_t file_size;
233         char *file_contents = read_file (linkname, RF_BINARY, &file_size);
234         ASSERT (file_size == 12);
235         ASSERT (memcmp (file_contents, "Hello world\n", 12) == 0);
236 
237         /* Clean up.  */
238         unlink (linkname);
239       }
240   }
241 
242   /* Test the case that the file is a symbolic link to a nonexistent file in a
243      nonexistent directory.  */
244   {
245     const char *linkname = "link4";
246     unlink (linkname);
247     if (symlink ("/nonexistent/gnulibtest8237/24715863701440", linkname) >= 0)
248       {
249         ASSERT (stat (linkname, &statbuf) < 0);
250 
251         struct supersede_final_action action;
252         FILE *fp =
253           fopen_supersede (linkname, "wb",
254                            supersede_if_exists, supersede_if_does_not_exist,
255                            &action);
256         ASSERT (fp == NULL);
257         ASSERT (errno == ENOENT);
258 
259         ASSERT (stat (linkname, &statbuf) < 0);
260 
261         /* Clean up.  */
262         unlink (linkname);
263       }
264   }
265 
266   /* Clean up.  */
267   unlink (filename);
268   rmdir (dir);
269 }
270