1 /**
2 * FDleak leaks dead file descriptors (and cleans them up)
3 * Copyright (C) 2022 Aaron Ball, nullspoon@oper.io
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 <http://www.gnu.org/licenses/>.
17 */
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <unistd.h> // Provides unlink
21 #include <signal.h>
22 #include <string.h>
23 #include <errno.h>
24
25 #include <sys/resource.h>
26
27 FILE** FDS;
28
29 void cleanup() {
30 long i = 0;
31 printf("Freeing leaked files\n");
32 while(FDS[i] != NULL) {
33 printf("Closing leaked file %ld\n", i);
34 fclose(FDS[i]);
35 i++;
36 }
37 free(FDS);
38 }
39
40 void handler(int sig) {
41 cleanup();
42 exit(128);
43 }
44
45 FILE* leakfd(char* path) {
46 FILE* fd = NULL;
47 fd = fopen(path, "w");
48 if(!fd)
49 return NULL;
50 fprintf(fd, "Ohhai!\n");
51 fflush(fd);
52 unlink(path); // Ahhhhhh
53 return fd; // Much logic, very sense
54 }
55
56 int main(int argc, char* argv[]) {
57 long count = 0;
58 long i = 0;
59 char fdpath[256];
60 signal(SIGINT, handler);
61 struct rlimit rl;
62
63 // Set soft limit to max
64 getrlimit(RLIMIT_NOFILE, &rl);
65 rl.rlim_cur = rl.rlim_max;
66
67 if(setrlimit(RLIMIT_NOFILE, &rl) != 0) {
68 printf("Error setting soft limit on open files\n");
69 printf("%s\n", strerror(errno));
70 return 1;
71 }
72
73 if(argc == 1) {
74 printf("Desccriptor leak count required\n");
75 return 1;
76 }
77 count = strtol(argv[1], NULL, 10);
78
79 // Block at 3 less than max because stdin, stdout, and stderr
80 if(count > (rl.rlim_cur) - 3) {
81 printf("ERROR: Requested FD leaks exceeds allowed maximum of %ld\n",
82 rl.rlim_cur - 3);
83 return 1;
84 }
85
86 // Allocate memory for descriptor array
87 FDS = malloc((sizeof(FILE*) * count) + 1);
88 memset(FDS, 0, count + 1);
89
90 while(i < count) {
91 sprintf(fdpath, "/tmp/fdleak-%ld.txt", i);
92 printf("Leaking file %s\n", fdpath);
93 FDS[i] = leakfd(fdpath);
94 if(FDS[i] == NULL) {
95 cleanup();
96 printf("ERROR opening file descriptor %ld, %s\n", i, fdpath);
97 printf("%s\n", strerror(errno));
98 return 1;
99 }
100 i++;
101 }
102
103 printf("Done. Press Enter to free memory.\n");
104 fgetc(stdin);
105 cleanup();
106
107 return 0;
108 }
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