[fuzzer][afl] Remove AFL_DRIVER_EXTRA_STATS_FILENAME

Summary:
Remove this feature as it is unused, buggy, and not worth correcting
since the forkserver makes it difficult.

Reviewers: morehouse, jfb

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D57308

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@352392 91177308-0d34-0410-b5e6-96231b3b80d8

Author: metzman

afl/afl_driver.cpp

@@ -31,32 +31,18 @@ clang++ afl_driver.cpp test_fuzzer.o afl-llvm-rt.o.o
 rm -rf IN OUT; mkdir IN OUT; echo z > IN/z;
 $AFL_HOME/afl-fuzz -i IN -o OUT ./a.out
 ################################################################################
-Environment Variables:
-There are a few environment variables that can be set to use features that
-afl-fuzz doesn't have.
-
-AFL_DRIVER_STDERR_DUPLICATE_FILENAME: Setting this *appends* stderr to the file
-specified. If the file does not exist, it is created. This is useful for getting
-stack traces (when using ASAN for example) or original error messages on hard to
-reproduce bugs.
-
-AFL_DRIVER_EXTRA_STATS_FILENAME: Setting this causes afl_driver to write extra
-statistics to the file specified. Currently these are peak_rss_mb
-(the peak amount of virtual memory used in MB) and slowest_unit_time_secs. If
-the file does not exist it is created. If the file does exist then
-afl_driver assumes it was restarted by afl-fuzz and will try to read old
-statistics from the file. If that fails then the process will quit.
+AFL_DRIVER_STDERR_DUPLICATE_FILENAME: Setting this environment variable
+*appends* stderr to the file specified. If the file does not exist, it is
+created. This is useful for getting stack traces (when using ASAN for example)
+or original error messages on hard to reproduce bugs.
 
 */
 #include <assert.h>
 #include <errno.h>
-#include <signal.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/resource.h>
-#include <sys/time.h>
 #include <unistd.h>
 
 #include <fstream>
@@ -98,17 +84,6 @@ statistics from the file. If that fails then the process will quit.
 #error "Support for your platform has not been implemented"
 #endif
 
-// Used to avoid repeating error checking boilerplate. If cond is false, a
-// fatal error has occurred in the program. In this event print error_message
-// to stderr and abort(). Otherwise do nothing. Note that setting
-// AFL_DRIVER_STDERR_DUPLICATE_FILENAME may cause error_message to be appended
-// to the file as well, if the error occurs after the duplication is performed.
-#define CHECK_ERROR(cond, error_message)                                       \
-  if (!(cond)) {                                                               \
-    fprintf(stderr, "%s\n", (error_message));                                  \
-    abort();                                                                   \
-  }
-
 // libFuzzer interface is thin, so we don't include any libFuzzer headers.
 extern "C" {
 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
@@ -129,14 +104,6 @@ static volatile char suppress_warning1 = AFL_DEFER_FORKSVR[0];
 static const size_t kMaxAflInputSize = 1 << 20;
 static uint8_t AflInputBuf[kMaxAflInputSize];
 
-// Variables we need for writing to the extra stats file.
-static FILE *extra_stats_file = NULL;
-static uint32_t previous_peak_rss = 0;
-static time_t slowest_unit_time_secs = 0;
-static const int kNumExtraStats = 2;
-static const char *kExtraStatsFormatString = "peak_rss_mb            : %u\n"
-                                             "slowest_unit_time_sec  : %u\n";
-
 // Experimental feature to use afl_driver without AFL's deferred mode.
 // Needs to run before __afl_auto_init.
 __attribute__((constructor(0))) void __decide_deferred_forkserver(void) {
@@ -148,117 +115,6 @@ __attribute__((constructor(0))) void __decide_deferred_forkserver(void) {
   }
 }
 
-// Copied from FuzzerUtil.cpp.
-size_t GetPeakRSSMb() {
-  struct rusage usage;
-  if (getrusage(RUSAGE_SELF, &usage))
-    return 0;
-  if (LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||
-      LIBFUZZER_OPENBSD) {
-    // ru_maxrss is in KiB
-    return usage.ru_maxrss >> 10;
-  } else if (LIBFUZZER_APPLE) {
-    // ru_maxrss is in bytes
-    return usage.ru_maxrss >> 20;
-  }
-  assert(0 && "GetPeakRSSMb() is not implemented for your platform");
-  return 0;
-}
-
-// Based on SetSigaction in FuzzerUtil.cpp
-static void SetSigaction(int signum,
-                         void (*callback)(int, siginfo_t *, void *)) {
-  struct sigaction sigact;
-  memset(&sigact, 0, sizeof(sigact));
-  sigact.sa_sigaction = callback;
-  if (sigaction(signum, &sigact, 0)) {
-    fprintf(stderr, "libFuzzer: sigaction failed with %d\n", errno);
-    exit(1);
-  }
-}
-
-// Write extra stats to the file specified by the user. If none is specified
-// this function will never be called.
-static void write_extra_stats() {
-  uint32_t peak_rss = GetPeakRSSMb();
-
-  if (peak_rss < previous_peak_rss)
-    peak_rss = previous_peak_rss;
-
-  int chars_printed = fprintf(extra_stats_file, kExtraStatsFormatString,
-                              peak_rss, slowest_unit_time_secs);
-
-  CHECK_ERROR(chars_printed != 0, "Failed to write extra_stats_file");
-
-  CHECK_ERROR(fclose(extra_stats_file) == 0,
-              "Failed to close extra_stats_file");
-}
-
-// Call write_extra_stats before we exit.
-static void crash_handler(int, siginfo_t *, void *) {
-  // Make sure we don't try calling write_extra_stats again if we crashed while
-  // trying to call it.
-  static bool first_crash = true;
-  CHECK_ERROR(first_crash,
-              "Crashed in crash signal handler. This is a bug in the fuzzer.");
-
-  first_crash = false;
-  write_extra_stats();
-}
-
-// If the user has specified an extra_stats_file through the environment
-// variable AFL_DRIVER_EXTRA_STATS_FILENAME, then perform necessary set up
-// to write stats to it on exit. If no file is specified, do nothing. Otherwise
-// install signal and exit handlers to write to the file when the process exits.
-// Then if the file doesn't exist create it and set extra stats to 0. But if it
-// does exist then read the initial values of the extra stats from the file
-// and check that the file is writable.
-static void maybe_initialize_extra_stats() {
-  // If AFL_DRIVER_EXTRA_STATS_FILENAME isn't set then we have nothing to do.
-  char *extra_stats_filename = getenv("AFL_DRIVER_EXTRA_STATS_FILENAME");
-  if (!extra_stats_filename)
-    return;
-
-  // Open the file and find the previous peak_rss_mb value.
-  // This is necessary because the fuzzing process is restarted after N
-  // iterations are completed. So we may need to get this value from a previous
-  // process to be accurate.
-  extra_stats_file = fopen(extra_stats_filename, "r");
-
-  // If extra_stats_file already exists: read old stats from it.
-  if (extra_stats_file) {
-    int matches = fscanf(extra_stats_file, kExtraStatsFormatString,
-                         &previous_peak_rss, &slowest_unit_time_secs);
-
-    // Make sure we have read a real extra stats file and that we have used it
-    // to set slowest_unit_time_secs and previous_peak_rss.
-    CHECK_ERROR(matches == kNumExtraStats, "Extra stats file is corrupt");
-
-    CHECK_ERROR(fclose(extra_stats_file) == 0, "Failed to close file");
-
-    // Now open the file for writing.
-    extra_stats_file = fopen(extra_stats_filename, "w");
-    CHECK_ERROR(extra_stats_file,
-                "Failed to open extra stats file for writing");
-  } else {
-    // Looks like this is the first time in a fuzzing job this is being called.
-    extra_stats_file = fopen(extra_stats_filename, "w+");
-    CHECK_ERROR(extra_stats_file, "failed to create extra stats file");
-  }
-
-  // Make sure that crash_handler gets called on any kind of fatal error.
-  int crash_signals[] = {SIGSEGV, SIGBUS, SIGABRT, SIGILL, SIGFPE,  SIGINT,
-                         SIGTERM};
-
-  const size_t num_signals = sizeof(crash_signals) / sizeof(crash_signals[0]);
-
-  for (size_t idx = 0; idx < num_signals; idx++)
-    SetSigaction(crash_signals[idx], crash_handler);
-
-  // Make sure it gets called on other kinds of exits.
-  atexit(write_extra_stats);
-}
-
 // If the user asks us to duplicate stderr, then do it.
 static void maybe_duplicate_stderr() {
   char* stderr_duplicate_filename =
@@ -323,7 +179,6 @@ int main(int argc, char **argv) {
   // Do any other expensive one-time initialization here.
 
   maybe_duplicate_stderr();
-  maybe_initialize_extra_stats();
 
   if (!getenv("AFL_DRIVER_DONT_DEFER"))
     __afl_manual_init();
@@ -344,7 +199,6 @@ int main(int argc, char **argv) {
   uint8_t dummy_input[1] = {0};
   LLVMFuzzerTestOneInput(dummy_input, 1);
 
-  time_t unit_time_secs;
   int num_runs = 0;
   while (__afl_persistent_loop(N)) {
     ssize_t n_read = read(0, AflInputBuf, kMaxAflInputSize);
@@ -353,23 +207,8 @@ int main(int argc, char **argv) {
       // overflows. Don't use unique_ptr/etc to avoid extra dependencies.
       uint8_t *copy = new uint8_t[n_read];
       memcpy(copy, AflInputBuf, n_read);
-
-      struct timeval unit_start_time;
-      CHECK_ERROR(gettimeofday(&unit_start_time, NULL) == 0,
-                  "Calling gettimeofday failed");
-
       num_runs++;
       LLVMFuzzerTestOneInput(copy, n_read);
-
-      struct timeval unit_stop_time;
-      CHECK_ERROR(gettimeofday(&unit_stop_time, NULL) == 0,
-                  "Calling gettimeofday failed");
-
-      // Update slowest_unit_time_secs if we see a new max.
-      unit_time_secs = unit_stop_time.tv_sec - unit_start_time.tv_sec;
-      if (slowest_unit_time_secs < unit_time_secs)
-        slowest_unit_time_secs = unit_time_secs;
-
       delete[] copy;
     }
   }