[compiler-rt] 03aa02a - [fuzzer] Use puts() rather than printf() in CopyFileToErr()

[Voss, Matthew via llvm-commits]

Hi Roy,

We're seeing the tests in this commit fail on the buildbots and our internal CI. Could you take a look?

https://lab.llvm.org/buildbot/#/builders/75/builds/28688

Thanks,
Matt

> -----Original Message-----
> From: llvm-commits <llvm-commits-bounces at lists.llvm.org> On Behalf Of Roy
> Sundahl via llvm-commits
> Sent: Friday, March 17, 2023 9:09 AM
> To: llvm-commits at lists.llvm.org
> Subject: [compiler-rt] 03aa02a - [fuzzer] Use puts() rather than printf() in
> CopyFileToErr()
> 
> 
> Author: Roy Sundahl
> Date: 2023-03-17T09:08:40-07:00
> New Revision: 03aa02adb03c928ae4ec9d139b303348f81861c9
> 
> URL: INVALID URI REMOVED
> project/commit/03aa02adb03c928ae4ec9d139b303348f81861c9__;!!JmoZiZGB
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> JPCEy-VEDGhh5KfT3xHxrXIomi08gYjNd$
> DIFF: INVALID URI REMOVED
> project/commit/03aa02adb03c928ae4ec9d139b303348f81861c9.diff__;!!JmoZi
> ZGBv3RvKRSx!9EDSpCy7vfS7tRXhmBZItcrI_1cPftXcbQNbOHxZpOkqASrl8RPXSVVs
> EPeJPCEy-VEDGhh5KfT3xHxrXIomi2uQopXu$
> 
> LOG: [fuzzer] Use puts() rather than printf() in CopyFileToErr()
> 
> CopyFileToErr() uses Printf("%s", ...) which fails with a negative size on files >2Gb
> (Its path is through var-args wrappers to an unnecessary "%s"
> expansion and subject to int overflows) Using puts() in place of printf() bypasses
> this path and writes the string directly to stderr. This avoids the present loss of
> data when a crashed worker has generated >2Gb of output.
> 
> rdar://99384640
> 
> Reviewed By: yln
> 
> Differential Revision:
> https://reviews.llvm.org/D146189
> 3RvKRSx!9EDSpCy7vfS7tRXhmBZItcrI_1cPftXcbQNbOHxZpOkqASrl8RPXSVVsEPeJ
> PCEy-VEDGhh5KfT3xHxrXIomi1H7oibf$
> 
> Added:
>     compiler-rt/test/fuzzer/BigFileCopy.cpp
>     compiler-rt/test/fuzzer/big-file-copy.test
> 
> Modified:
>     compiler-rt/lib/fuzzer/FuzzerIO.cpp
>     compiler-rt/lib/fuzzer/FuzzerIO.h
> 
> Removed:
> 
> 
> 
> #################################################################
> ###############
> diff  --git a/compiler-rt/lib/fuzzer/FuzzerIO.cpp b/compiler-
> rt/lib/fuzzer/FuzzerIO.cpp
> index 0a58c5377b34f..54cc4ee54be0a 100644
> --- a/compiler-rt/lib/fuzzer/FuzzerIO.cpp
> +++ b/compiler-rt/lib/fuzzer/FuzzerIO.cpp
> @@ -65,7 +65,7 @@ std::string FileToString(const std::string &Path) {  }
> 
>  void CopyFileToErr(const std::string &Path) {
> -  Printf("%s", FileToString(Path).c_str());
> +  Puts(FileToString(Path).c_str());
>  }
> 
>  void WriteToFile(const Unit &U, const std::string &Path) { @@ -151,6 +151,11
> @@ void CloseStdout() {
>    DiscardOutput(1);
>  }
> 
> +void Puts(const char *Str) {
> +  fputs(Str, OutputFile);
> +  fflush(OutputFile);
> +}
> +
>  void Printf(const char *Fmt, ...) {
>    va_list ap;
>    va_start(ap, Fmt);
> 
> diff  --git a/compiler-rt/lib/fuzzer/FuzzerIO.h b/compiler-rt/lib/fuzzer/FuzzerIO.h
> index 401afa0b44773..874caad1baedb 100644
> --- a/compiler-rt/lib/fuzzer/FuzzerIO.h
> +++ b/compiler-rt/lib/fuzzer/FuzzerIO.h
> @@ -58,6 +58,7 @@ void CloseStdout();
>  FILE *GetOutputFile();
>  void SetOutputFile(FILE *NewOutputFile);
> 
> +void Puts(const char *Str);
>  void Printf(const char *Fmt, ...);
>  void VPrintf(bool Verbose, const char *Fmt, ...);
> 
> 
> diff  --git a/compiler-rt/test/fuzzer/BigFileCopy.cpp b/compiler-
> rt/test/fuzzer/BigFileCopy.cpp
> new file mode 100644
> index 0000000000000..42a2a84f82fc9
> --- /dev/null
> +++ b/compiler-rt/test/fuzzer/BigFileCopy.cpp
> @@ -0,0 +1,32 @@
> +// Part of the LLVM Project, under the Apache License v2.0 with LLVM
> Exceptions.
> +// See
> https://llvm.org/LICENSE.txt
> Sx!9EDSpCy7vfS7tRXhmBZItcrI_1cPftXcbQNbOHxZpOkqASrl8RPXSVVsEPeJPCEy-
> VEDGhh5KfT3xHxrXIomizVkWCgM$  for license information.
> +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
> +
> +#include <cstddef>
> +#include <cstdint>
> +#include <cstdio>
> +#include <cstdlib>
> +#include <cstring>
> +
> +#include "FuzzerIO.h"
> +
> +int main(int argc, char *argv[]) {
> +  assert(argc == 2);
> +  const char *FileName = argv[1];
> +  FILE *f = fopen(FileName, "w");
> +
> +  // This is the biggest file possible unless CopyFileToErr() uses
> + Puts()  fprintf(f, "%2147483646s", "2Gb-2");
> +
> +  // This makes the file too big if CopyFileToErr() uses fprintf("%s",
> + <file>)  fprintf(f, "THIS LINE RESPONSIBLE FOR EXCEEDING 2Gb FILE
> + SIZE\n");  fclose(f);
> +
> +  // Should now because CopyFileToErr() now uses Puts()
> + fuzzer::CopyFileToErr(FileName);
> +
> +  // File is >2Gb so clean up
> +  remove(FileName);
> +
> +  return 0;
> +}
> 
> diff  --git a/compiler-rt/test/fuzzer/big-file-copy.test b/compiler-
> rt/test/fuzzer/big-file-copy.test
> new file mode 100644
> index 0000000000000..642b7cbf154e4
> --- /dev/null
> +++ b/compiler-rt/test/fuzzer/big-file-copy.test
> @@ -0,0 +1,4 @@
> +RUN: %cpp_compiler %S/BigFileCopy.cpp -o %t
> +RUN: %run %t big-file.txt 2>big-file-out.txt; result=$?
> +RUN: %run rm -f big-file.txt big-file-out.txt
> +RUN: %run (exit $result)
> 
> 
> 
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