1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include <assert.h>
18 #include <errno.h>
19 #include <fcntl.h>
20 #include <getopt.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <unistd.h>
25 
26 #include <logwrap/logwrap.h>
27 #include <sys/stat.h>
28 #include <sys/statvfs.h>
29 #include <utils/Log.h>
30 
31 #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
32 
33 #define MAX_IO_WRITE_CHUNK_SIZE 0x100000
34 
35 #ifndef min
36 #define min(a,b) ((a) < (b) ? (a) : (b))
37 #endif
38 
39 typedef unsigned long u64;
40 
usage(const char * const progname)41 static void usage(const char * const progname) {
42     fprintf(stderr,
43             "Usage: %s [-s <seed>] -h <hole size in bytes> -t <total hole size in bytes> "
44             "path\n",
45             progname);
46 }
47 
get_free_space(const char * const path)48 static u64 get_free_space(const char * const path) {
49     struct statvfs s;
50 
51     if (statvfs(path, &s) < 0) {
52         fprintf(stderr, "\nerrno: %d. Failed to get free disk space on %s\n",
53                 errno, path);
54         return 0;
55     } else {
56         return (u64)s.f_bsize * (u64)s.f_bfree;
57     }
58 }
59 
get_random_num(const u64 start,const u64 end)60 static u64 get_random_num(const u64 start, const u64 end) {
61     if (end - start <= 0)
62         return start;
63     assert(RAND_MAX >= 0x7FFFFFFF);
64     if ((end - start) > 0x7FFFFFFF)
65         return start + (((u64)random() << 31) | (u64)random()) % (end - start);
66     return start + (random() % (end - start));
67 }
68 
get_random_char()69 static char get_random_char() {
70     return 'A' + random() % ('Z' - 'A');
71 }
72 
create_unique_file(const char * const dir_path,const u64 size,const u64 id,char * const base,const u64 base_length)73 static bool create_unique_file(const char * const dir_path, const u64 size,
74                                const u64 id, char * const base,
75                                const u64 base_length) {
76     u64 length = 0;
77     int fd;
78     char file_path[FILENAME_MAX];
79     bool ret = true;
80 
81     base[random() % min(base_length, size)] = get_random_char();
82 
83     sprintf(file_path, "%s/file_%lu", dir_path, id);
84     fd = open(file_path, O_WRONLY | O_CREAT | O_SYNC, 0777);
85     if (fd < 0) {
86         // We suppress ENOSPC erros as that is common as we approach the
87         // last few MBs of the fs as we don't account for the size of the newly
88         // added meta data after the initial free space computation.
89         if (errno != 28) {
90             fprintf(stderr, "\nerrno: %d. Failed to create %s\n", errno, file_path);
91         }
92         return false;
93     }
94     while (length + base_length < size) {
95         if (write(fd, base, base_length) < 0) {
96             if (errno != 28) {
97                 fprintf(stderr, "\nerrno: %d. Failed to write %lu bytes to %s\n",
98                         errno, base_length, file_path);
99             }
100             ret = false;
101             goto done;
102         }
103         length += base_length;
104     }
105     if (write(fd, base, size - length) < 0) {
106         if (errno != 28) {
107             fprintf(stderr, "\nerrno: %d. Failed to write last %lu bytes to %s\n",
108                     errno, size - length, file_path);
109         }
110         ret = false;
111         goto done;
112     }
113 done:
114     if (close(fd) < 0) {
115         fprintf(stderr, "\nFailed to close %s\n", file_path);
116         ret = false;
117     }
118     return ret;
119 }
120 
create_unique_dir(char * dir,const char * const root_path)121 static bool create_unique_dir(char *dir, const char * const root_path) {
122     char random_string[15];
123     int i;
124 
125     for (i = 0; i < 14; ++i) {
126         random_string[i] = get_random_char();
127     }
128     random_string[14] = '\0';
129 
130     sprintf(dir, "%s/%s", root_path, random_string);
131 
132     if (mkdir(dir, 0777) < 0) {
133         fprintf(stderr, "\nerrno: %d. Failed to create %s\n", errno, dir);
134         return false;
135     }
136     return true;
137 }
138 
puncture_fs(const char * const path,const u64 total_size,const u64 hole_size,const u64 total_hole_size)139 static bool puncture_fs (const char * const path, const u64 total_size,
140                          const u64 hole_size, const u64 total_hole_size) {
141     u64 increments = (hole_size * total_size) / total_hole_size;
142     u64 hole_max;
143     u64 starting_max = 0;
144     u64 ending_max = increments;
145     char stay_dir[FILENAME_MAX], delete_dir[FILENAME_MAX];
146     char *rm_bin_argv[] = { "/system/bin/rm", "-rf", ""};
147     u64 file_id = 1;
148     char *base_file_data;
149     u64 i = 0;
150 
151     if (!create_unique_dir(stay_dir, path) ||
152         !create_unique_dir(delete_dir, path)) {
153         return false;
154     }
155 
156     base_file_data = (char*) malloc(MAX_IO_WRITE_CHUNK_SIZE);
157     for (i = 0; i < MAX_IO_WRITE_CHUNK_SIZE; ++i) {
158         base_file_data[i] = get_random_char();
159     }
160     fprintf(stderr, "\n");
161     while (ending_max <= total_size) {
162         fprintf(stderr, "\rSTAGE 1/2: %d%% Complete",
163                 (int) (100.0 * starting_max / total_size));
164         hole_max = get_random_num(starting_max, ending_max);
165 
166 	do {
167 		hole_max = get_random_num(starting_max, ending_max);
168 	} while (hole_max == starting_max);
169 
170         create_unique_file(stay_dir,
171                            hole_max - starting_max,
172                            file_id++,
173                            base_file_data,
174                            MAX_IO_WRITE_CHUNK_SIZE);
175         create_unique_file(delete_dir,
176                            hole_size,
177                            file_id++,
178                            base_file_data,
179                            MAX_IO_WRITE_CHUNK_SIZE);
180 
181         starting_max = hole_max + hole_size;
182         ending_max += increments;
183     }
184     create_unique_file(stay_dir,
185                        (ending_max - increments - starting_max),
186                        file_id++,
187                        base_file_data,
188                        MAX_IO_WRITE_CHUNK_SIZE);
189     fprintf(stderr, "\rSTAGE 1/2: 100%% Complete\n");
190     fprintf(stderr, "\rSTAGE 2/2: 0%% Complete");
191     free(base_file_data);
192     rm_bin_argv[2] = delete_dir;
193     if (android_fork_execvp_ext(ARRAY_SIZE(rm_bin_argv), rm_bin_argv,
194                                 NULL, 1, LOG_KLOG, 0, NULL, NULL, 0) < 0) {
195         fprintf(stderr, "\nFailed to delete %s\n", rm_bin_argv[2]);
196         return false;
197     }
198     fprintf(stderr, "\rSTAGE 2/2: 100%% Complete\n");
199     return true;
200 }
201 
main(const int argc,char ** const argv)202 int main (const int argc, char ** const argv) {
203     int opt;
204     int mandatory_opt;
205     char *path = NULL;
206     int seed = time(NULL);
207 
208     u64 total_size = 0;
209     u64 hole_size = 0;
210     u64 total_hole_size = 0;
211 
212     mandatory_opt = 2;
213     while ((opt = getopt(argc, argv, "s:h:t:")) != -1) {
214         switch(opt) {
215             case 's':
216                 seed = atoi(optarg);
217                 break;
218             case 'h':
219                 hole_size = atoll(optarg);
220                 mandatory_opt--;
221                 break;
222             case 't':
223                 total_hole_size = atoll(optarg);
224                 mandatory_opt--;
225                 break;
226             default:
227                 usage(argv[0]);
228                 exit(EXIT_FAILURE);
229         }
230     }
231     if (mandatory_opt) {
232         usage(argv[0]);
233         exit(EXIT_FAILURE);
234     }
235     if (optind >= argc) {
236         fprintf(stderr, "\nExpected path name after options.\n");
237         usage(argv[0]);
238         exit(EXIT_FAILURE);
239     }
240     path = argv[optind++];
241 
242     if (optind < argc) {
243         fprintf(stderr, "\nUnexpected argument: %s\n", argv[optind]);
244         usage(argv[0]);
245         exit(EXIT_FAILURE);
246     }
247 
248     srandom(seed);
249     fprintf(stderr, "\nRandom seed is: %d\n", seed);
250 
251     total_size = get_free_space(path);
252     if (!total_size) {
253         exit(EXIT_FAILURE);
254     }
255     if (total_size < total_hole_size || total_hole_size < hole_size) {
256         fprintf(stderr, "\nInvalid sizes: total available size should be "
257                         "larger than total hole size which is larger than "
258                         "hole size\n");
259         exit(EXIT_FAILURE);
260     }
261 
262     if (!puncture_fs(path, total_size, hole_size, total_hole_size)) {
263         exit(EXIT_FAILURE);
264     }
265     return 0;
266 }
267