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| // RUN: %clang_dfsan %s -o %t && %run %t | FileCheck %s
// RUN: %clang_dfsan -mllvm -dfsan-args-abi %s -o %t && %run %t | FileCheck %s
// Tests that the custom implementation of write() does writes with or without
// a callback set using dfsan_set_write_callback().
// REQUIRES: stable-runtime
#include <sanitizer/dfsan_interface.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
// Check write callback arguments by having the callback store them in
// the following variables:
static int last_callback_arg_fd;
static const void *last_callback_arg_buf;
static size_t last_callback_arg_count;
// Allow tests to check the number of callbacks made by incrementing
// this count. When callbacks are verified, the count is reset.
static int count_unverified_callbacks = 0;
// This callbact will be installed using dfsan_set_write_callback()
// in tests below.
static void write_callback(int fd, const void *buf, size_t count) {
// Do not do anything in this function that might call write().
count_unverified_callbacks++;
last_callback_arg_fd = fd;
last_callback_arg_buf = buf;
last_callback_arg_count = count;
}
static void write_string_to_stdout(char *string) {
char *cur = string;
int bytes_left = strlen(string);
while (bytes_left > 0) {
int res = write(fileno(stdout), cur, bytes_left);
assert (res >= 0);
cur += res;
bytes_left -= res;
}
}
static void test_can_write_without_callback() {
dfsan_set_write_callback(NULL);
count_unverified_callbacks = 0;
char aString[] = "Test that writes work without callback.\n";
// CHECK: Test that writes work without callback.
write_string_to_stdout(aString);
assert(count_unverified_callbacks == 0);
}
static void test_can_write_with_callback() {
dfsan_set_write_callback(write_callback);
count_unverified_callbacks = 0;
char stringWithCallback[] = "Test that writes work with callback.\n";
// CHECK: Test that writes work with callback.
write_string_to_stdout(stringWithCallback);
// Data was written, so at least one call to write() was made.
// Because a write may not process all the bytes it is passed, there
// may have been several calls to write().
assert(count_unverified_callbacks > 0);
count_unverified_callbacks = 0;
dfsan_set_write_callback(NULL);
char stringWithoutCallback[] = "Writes work after the callback is removed.\n";
// CHECK: Writes work after the callback is removed.
write_string_to_stdout(stringWithoutCallback);
assert(count_unverified_callbacks == 0);
}
static void test_failing_write_runs_callback() {
// Open /dev/null in read-only mode. Calling write() on fd will fail.
int fd = open("/dev/null", O_RDONLY);
assert(fd != -1);
// Install a callback.
dfsan_set_write_callback(write_callback);
// Write to the read-only file handle. The write will fail, but the callback
// should still be invoked.
char aString[] = "This text will fail to be written.\n";
int len = strlen(aString);
int write_result = write(fd, aString, len);
assert(write_result == -1);
assert(count_unverified_callbacks == 1);
count_unverified_callbacks = 0;
assert(fd == last_callback_arg_fd);
assert(aString == last_callback_arg_buf);
assert(len == last_callback_arg_count);
close(fd);
}
int main(int argc, char* argv[]) {
test_can_write_without_callback();
test_can_write_with_callback();
test_failing_write_runs_callback();
}
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