scan-build fails when output directory contains a percent sign (%)

yscialom commented 5 years ago

Description

Whenever I'm in a directory whose fullpath contains the percent sign character (%, \x25), scan-build fails by reporting no bug.

Reproduction & Observed behaviour

$ mkdir -p /tmp/scan-build-bug/path_with_%_in_it
$ cd /tmp/scan-build-bug/path_with_%_in_it
$ echo 'void f() { auto a = new int; delete a; *a = 0; }' > bug.cpp
$ scan-build -o . make bug.o
scan-build: Using '/usr/bin/clang' for static analysis
/usr/libexec/clang-analyzer/scan-build/c++-analyzer    -c -o bug.o bug.cpp
bug.cpp:1:43: warning: Use of memory after it is freed
void f() { auto a = new int; delete a; *a = 0; }
                                       ~~ ^
warning: could not create file in '/tmp/scan-build-bug/path_with_%_in_it/2019-09-04-123616-2401-1': No such file or directory
1 warning generated.
scan-build: Removing directory '/tmp/scan-build-bug/path_with_%_in_it/2019-09-04-123616-2401-1' because it contains no reports.
scan-build: No bugs found.

Expected behaviour

$ mkdir -p /tmp/scan-build-bug/nominal
$ cd /tmp/scan-build-bug/nominal
$ echo 'void f() { auto a = new int; delete a; *a = 0; }' > bug.cpp
$ scan-build -o . make bug.o
scan-build: Using '/usr/bin/clang' for static analysis
/usr/libexec/clang-analyzer/scan-build/c++-analyzer    -c -o bug.o bug.cpp
bug.cpp:1:43: warning: Use of memory after it is freed
void f() { auto a = new int; delete a; *a = 0; }
                                       ~~ ^
1 warning generated.
scan-build: 1 bugs found.
scan-build: Run 'scan-view /tmp/scan-build-bug/nominal/2019-09-04-123649-2667-1' to examine bug reports.

Why it matters: it could ending up failing jobs silently

Well, % has no special meaning in filesystems I know. I personally use it to urlencode my jenkins jobs pathes (e.g. <root>/<project_name>/<branch>/<job_id> --> "$JENKINS_HOME/My+Awesome+Project/feature%2Fspit-fire/42"). The thing is, I run scan-build cmake before running scan-build make -o /some/proper/path. On that first run, scan-build fails silently as no bugs are expected, and for some reason it makes the second run fail.

I could work around it by using another scheme than urlencode, or adding a -o $(mktemp -d) for the first run, but come on!

Technical details

Tested on:

Centos 7.6 : uname -a: Linux ysc-dev-01 3.10.0-957.12.1.el7.x86_64 #1 SMP Mon Apr 29 14:59:59 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux shell: zsh ** version: 3.4.2-9, installed from RPM
Red Hat 7.? uname -a: Linux --censored-- 3.10.0-957.27.2.el7.x86_64 #1 SMP Tue Jul 9 16:53:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux shell: bash ** version: 3.4.2-9, installed from RPM

yscialom commented 5 years ago

In fact this is even worse, scan-build ... cmake doesn't work at all if the path contains a %, no workaround found:

$ mkdir -p /tmp/scan-build-bug/cmake-with%
$ cd /tmp/scan-build-bug/cmake-with%
$ echo -e 'cmake_minimum_required (VERSION 3.1)\nproject(HELLO)\nadd_library(hello bug.cpp)' > CMakeLists.txt'
$ echo 'void f() { auto a = new int; delete a; *a = 0; }' > bug.cpp
$ scan-build -o $(mktemp -d) cmake3 .
scan-build: Using '/usr/bin/clang' for static analysis
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/scan-build-bug/cmake-with%
scan-build: Removing directory '/tmp/tmp.o99DJj0TEI/2019-09-04-144135-6851-1' because it contains no reports.
scan-build: No bugs found.
$ scan-build -o $(mktemp -d) make .  
scan-build: Using '/usr/bin/clang' for static analysis
scan-build: Removing directory '/tmp/tmp.HvpdLKhP37/2019-09-04-144140-6919-1' because it contains no reports.
scan-build: No bugs found.
$ ls bug*
buf.cpp

bug.o and libhello.a havn't been built!

rizsotto commented 5 years ago

Hi @yscialom , thanks for the report. Interesting bug. Will look at it on the weekend.

As a workaround I would suggest not to use percent sign in the output directory. ;)

rizsotto commented 5 years ago

I did an investigation, and I've found that the line

warning: could not create file in '...': No such file or directory

is emited by Clang, not the scan-build. Which means, I can't really fix it. I would recommend to open a bug on Clang for this. And as a workaround, try to use another separator than %.

yscialom commented 5 years ago

This does not explain why scan-build cmake .. fails silently then.

rizsotto commented 5 years ago

I think, it's still possible that scan-build cmake .. is fine.

I don't know what compiler your project is using. But if it's using gcc during the build (and the cmake run), that does not suffer from this bug.
And if you are using Clang, it has multiple modes. I saw that the "static-analyzer" mode fails if the % is in the output name. There is a high chance that the "compile" or the "link" mode does not have problem with the percent sign in the output.

rizsotto commented 5 years ago

https://clang.llvm.org/doxygen/HTMLDiagnostics_8cpp_source.html#l00230 calls llvm::sys::fs::createUniqueFile which https://llvm.org/doxygen/Path_8cpp_source.html#l00741 substitues % characters in the whole path.

They should do it only on the filename, and not on the full path.

rizsotto / scan-build