1 // RUN: %clang_dfsan %s -o %t && %run %t | FileCheck %s
2 // RUN: %clang_dfsan -mllvm -dfsan-args-abi %s -o %t && %run %t | FileCheck %s
3
4 // Tests that the custom implementation of write() does writes with or without
5 // a callback set using dfsan_set_write_callback().
6 // REQUIRES: stable-runtime
7
8 #include <sanitizer/dfsan_interface.h>
9
10 #include <assert.h>
11 #include <fcntl.h>
12 #include <stdio.h>
13 #include <string.h>
14 #include <unistd.h>
15
16 // Check write callback arguments by having the callback store them in
17 // the following variables:
18 static int last_callback_arg_fd;
19 static const void *last_callback_arg_buf;
20 static size_t last_callback_arg_count;
21
22 // Allow tests to check the number of callbacks made by incrementing
23 // this count. When callbacks are verified, the count is reset.
24 static int count_unverified_callbacks = 0;
25
26 // This callbact will be installed using dfsan_set_write_callback()
27 // in tests below.
write_callback(int fd,const void * buf,size_t count)28 static void write_callback(int fd, const void *buf, size_t count) {
29 // Do not do anything in this function that might call write().
30 count_unverified_callbacks++;
31
32 last_callback_arg_fd = fd;
33 last_callback_arg_buf = buf;
34 last_callback_arg_count = count;
35 }
36
write_string_to_stdout(char * string)37 static void write_string_to_stdout(char *string) {
38 char *cur = string;
39 int bytes_left = strlen(string);
40 while (bytes_left > 0) {
41 int res = write(fileno(stdout), cur, bytes_left);
42 assert (res >= 0);
43 cur += res;
44 bytes_left -= res;
45 }
46 }
47
test_can_write_without_callback()48 static void test_can_write_without_callback() {
49 dfsan_set_write_callback(NULL);
50 count_unverified_callbacks = 0;
51
52 char aString[] = "Test that writes work without callback.\n";
53 // CHECK: Test that writes work without callback.
54 write_string_to_stdout(aString);
55
56 assert(count_unverified_callbacks == 0);
57 }
58
test_can_write_with_callback()59 static void test_can_write_with_callback() {
60 dfsan_set_write_callback(write_callback);
61
62 count_unverified_callbacks = 0;
63
64 char stringWithCallback[] = "Test that writes work with callback.\n";
65 // CHECK: Test that writes work with callback.
66 write_string_to_stdout(stringWithCallback);
67
68 // Data was written, so at least one call to write() was made.
69 // Because a write may not process all the bytes it is passed, there
70 // may have been several calls to write().
71 assert(count_unverified_callbacks > 0);
72 count_unverified_callbacks = 0;
73
74 dfsan_set_write_callback(NULL);
75
76 char stringWithoutCallback[] = "Writes work after the callback is removed.\n";
77 // CHECK: Writes work after the callback is removed.
78 write_string_to_stdout(stringWithoutCallback);
79 assert(count_unverified_callbacks == 0);
80 }
81
test_failing_write_runs_callback()82 static void test_failing_write_runs_callback() {
83 // Open /dev/null in read-only mode. Calling write() on fd will fail.
84 int fd = open("/dev/null", O_RDONLY);
85 assert(fd != -1);
86
87 // Install a callback.
88 dfsan_set_write_callback(write_callback);
89
90 // Write to the read-only file handle. The write will fail, but the callback
91 // should still be invoked.
92 char aString[] = "This text will fail to be written.\n";
93 int len = strlen(aString);
94 int write_result = write(fd, aString, len);
95 assert(write_result == -1);
96
97 assert(count_unverified_callbacks == 1);
98 count_unverified_callbacks = 0;
99
100 assert(fd == last_callback_arg_fd);
101 assert(aString == last_callback_arg_buf);
102 assert(len == last_callback_arg_count);
103
104 close(fd);
105 }
106
main(int argc,char * argv[])107 int main(int argc, char* argv[]) {
108 test_can_write_without_callback();
109 test_can_write_with_callback();
110 test_failing_write_runs_callback();
111 }
112