[llvm] r263831 - [libFuzzer] add a flag close_fd_mask so that we can silence spammy targets by closing stderr/stdout
Kostya Serebryany via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 18 13:58:30 PDT 2016
Author: kcc
Date: Fri Mar 18 15:58:29 2016
New Revision: 263831
URL: http://llvm.org/viewvc/llvm-project?rev=263831&view=rev
Log:
[libFuzzer] add a flag close_fd_mask so that we can silence spammy targets by closing stderr/stdout
Added:
llvm/trunk/lib/Fuzzer/test/SpamyTest.cpp
Modified:
llvm/trunk/docs/LibFuzzer.rst
llvm/trunk/lib/Fuzzer/FuzzerDriver.cpp
llvm/trunk/lib/Fuzzer/FuzzerFlags.def
llvm/trunk/lib/Fuzzer/FuzzerIO.cpp
llvm/trunk/lib/Fuzzer/FuzzerInternal.h
llvm/trunk/lib/Fuzzer/test/CMakeLists.txt
llvm/trunk/lib/Fuzzer/test/fuzzer.test
Modified: llvm/trunk/docs/LibFuzzer.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LibFuzzer.rst?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/docs/LibFuzzer.rst (original)
+++ llvm/trunk/docs/LibFuzzer.rst Fri Mar 18 15:58:29 2016
@@ -88,6 +88,7 @@ The most important flags are::
artifact_prefix "" Write fuzzing artifacts (crash, timeout, or slow inputs) as $(artifact_prefix)file
exact_artifact_path "" Write the single artifact on failure (crash, timeout) as $(exact_artifact_path). This overrides -artifact_prefix and will not use checksum in the file name. Do not use the same path for several parallel processes.
print_final_stats 0 If 1, print statistics at exit.
+ close_fd_mask 0 If 1, close stdout at startup; if 2, close stderr; if 3, close both.
For the full list of flags run the fuzzer binary with ``-help=1``.
Modified: llvm/trunk/lib/Fuzzer/FuzzerDriver.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerDriver.cpp?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerDriver.cpp (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerDriver.cpp Fri Mar 18 15:58:29 2016
@@ -260,6 +260,11 @@ static int FuzzerDriver(const std::vecto
return 0;
}
+ if (Flags.close_fd_mask & 2)
+ DupAndCloseStderr();
+ if (Flags.close_fd_mask & 1)
+ CloseStdout();
+
if (Flags.jobs > 0 && Flags.workers == 0) {
Flags.workers = std::min(NumberOfCpuCores() / 2, Flags.jobs);
if (Flags.workers > 1)
Modified: llvm/trunk/lib/Fuzzer/FuzzerFlags.def
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerFlags.def?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerFlags.def (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerFlags.def Fri Mar 18 15:58:29 2016
@@ -75,6 +75,8 @@ FUZZER_FLAG_INT(handle_abrt, 1, "If 1, t
FUZZER_FLAG_INT(handle_ill, 1, "If 1, try to intercept SIGILL.")
FUZZER_FLAG_INT(handle_fpe, 1, "If 1, try to intercept SIGFPE.")
FUZZER_FLAG_INT(handle_int, 1, "If 1, try to intercept SIGINT.")
+FUZZER_FLAG_INT(close_fd_mask, 0, "If 1, close stdout at startup; "
+ "if 2, close stderr; if 3, close both.")
FUZZER_DEPRECATED_FLAG(exit_on_first)
FUZZER_DEPRECATED_FLAG(save_minimized_corpus)
Modified: llvm/trunk/lib/Fuzzer/FuzzerIO.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerIO.cpp?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerIO.cpp (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerIO.cpp Fri Mar 18 15:58:29 2016
@@ -20,6 +20,8 @@
namespace fuzzer {
+static int OutputFd = 2;
+
bool IsFile(const std::string &Path) {
struct stat St;
if (stat(Path.c_str(), &St))
@@ -114,11 +116,25 @@ std::string DirPlusFile(const std::strin
return DirPath + "/" + FileName;
}
+void DupAndCloseStderr() {
+ assert(OutputFd == 2);
+ OutputFd = dup(OutputFd);
+ if (OutputFd < 0)
+ OutputFd = 2;
+ else
+ close(2);
+}
+
+void CloseStdout() { close(1); }
+
void Printf(const char *Fmt, ...) {
+ char Buf[1024];
va_list ap;
va_start(ap, Fmt);
- vfprintf(stderr, Fmt, ap);
+ int Formatted = vsnprintf(Buf, sizeof(Buf), Fmt, ap);
va_end(ap);
+ if (Formatted)
+ write(OutputFd, Buf, Formatted);
}
} // namespace fuzzer
Modified: llvm/trunk/lib/Fuzzer/FuzzerInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerInternal.h?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerInternal.h (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerInternal.h Fri Mar 18 15:58:29 2016
@@ -75,6 +75,8 @@ void CopyFileToErr(const std::string &Pa
std::string DirPlusFile(const std::string &DirPath,
const std::string &FileName);
+void DupAndCloseStderr();
+void CloseStdout();
void Printf(const char *Fmt, ...);
void PrintHexArray(const Unit &U, const char *PrintAfter = "");
void PrintHexArray(const uint8_t *Data, size_t Size,
Modified: llvm/trunk/lib/Fuzzer/test/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/test/CMakeLists.txt?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/test/CMakeLists.txt (original)
+++ llvm/trunk/lib/Fuzzer/test/CMakeLists.txt Fri Mar 18 15:58:29 2016
@@ -30,6 +30,7 @@ set(Tests
SimpleFnAdapterTest
SimpleHashTest
SimpleTest
+ SpamyTest
StrcmpTest
StrncmpTest
SwitchTest
Added: llvm/trunk/lib/Fuzzer/test/SpamyTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/test/SpamyTest.cpp?rev=263831&view=auto
==============================================================================
--- llvm/trunk/lib/Fuzzer/test/SpamyTest.cpp (added)
+++ llvm/trunk/lib/Fuzzer/test/SpamyTest.cpp Fri Mar 18 15:58:29 2016
@@ -0,0 +1,18 @@
+// The test spams to stderr and stdout.
+#include <assert.h>
+#include <cstdint>
+#include <cstdio>
+#include <cstddef>
+#include <iostream>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+ assert(Data);
+ printf("PRINTF_STDOUT\n");
+ fflush(stdout);
+ fprintf(stderr, "PRINTF_STDERR\n");
+ std::cout << "STREAM_COUT\n";
+ std::cout.flush();
+ std::cerr << "STREAM_CERR\n";
+ return 0;
+}
+
Modified: llvm/trunk/lib/Fuzzer/test/fuzzer.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/test/fuzzer.test?rev=263831&r1=263830&r2=263831&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/test/fuzzer.test (original)
+++ llvm/trunk/lib/Fuzzer/test/fuzzer.test Fri Mar 18 15:58:29 2016
@@ -91,3 +91,32 @@ FINAL_STATS: stat::new_units_added:
FINAL_STATS: stat::slowest_unit_time_sec: 0
FINAL_STATS: stat::peak_rss_mb:
+RUN: LLVMFuzzer-SpamyTest -runs=1 2>&1 | FileCheck %s --check-prefix=FD_MASK_0
+RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=0 2>&1 | FileCheck %s --check-prefix=FD_MASK_0
+RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=1 2>&1 | FileCheck %s --check-prefix=FD_MASK_1
+RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=2 2>&1 | FileCheck %s --check-prefix=FD_MASK_2
+RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=3 2>&1 | FileCheck %s --check-prefix=FD_MASK_3
+FD_MASK_0: PRINTF_STDOUT
+FD_MASK_0: PRINTF_STDERR
+FD_MASK_0: STREAM_COUT
+FD_MASK_0: STREAM_CERR
+FD_MASK_0: INITED
+
+FD_MASK_1-NOT: PRINTF_STDOUT
+FD_MASK_1: PRINTF_STDERR
+FD_MASK_1-NOT: STREAM_COUT
+FD_MASK_1: STREAM_CERR
+FD_MASK_1: INITED
+
+FD_MASK_2: PRINTF_STDOUT
+FD_MASK_2-NOT: PRINTF_STDERR
+FD_MASK_2: STREAM_COUT
+FD_MASK_2-NOTE: STREAM_CERR
+FD_MASK_2: INITED
+
+FD_MASK_3-NOT: PRINTF_STDOUT
+FD_MASK_3-NOT: PRINTF_STDERR
+FD_MASK_3-NOT: STREAM_COUT
+FD_MASK_3-NOT: STREAM_CERR
+FD_MASK_3: INITED
+
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