Comments (19)
@farcas-snps
Is it possble to use previous version for you?
from winflexbison.
Alright thanks @GitMensch , I'll update and prepare them
from winflexbison.
First part is in now, have fun with the other two :-)
from winflexbison.
I agree that this is bad. To have that code working correctly: _tmpnam
should only be used directly before the file is created - because it "checks if that file exists", doing it "up front" is the most problematic part (I still consider the use of tmpnam
better than creating a new folder for each invocation, which was done before).
In theory we could ship our own implementation which:
- uses the specified directory if it is set, otherwise TMP, otherwise TEMP
- additional uses an increasing number on each access
If this is done then the actual file io to check for the file possibly could be left out (otherwise stat the result).
... but as noted, I'd suggest to move the use of tmpnam
where it should be and claim victory.
Thanks @egorpugin for the bug submission and the check, can you go even a step further and provide a PR?
from winflexbison.
What about some ~flex_out_main_PID
name?
from winflexbison.
That would be the "own tmpnam" variant - but as noted: it should be the best option to just use tmpnam where it is intended to be.
from winflexbison.
You'll still get a race there.
The race is between tmpnam
and fopen
. Two processes can get the same name again.
name = tmpnam();
// <- race!
fopen(name)
from winflexbison.
You'll still get a race there. The race is between
tmpnam
andfopen
. Two processes can get the same name again.
That is unlikely if both calls are directly after each other (the problem you've experienced is because they are called "far away"; but depending on the tmpnam implementation possible (the one used with your environment, which I guess is a release distribution, does not use pid, others may do so).
To ensure that this does not happen it is necessary to (additional to placing both functions next to each other) using a different (in this case likely self-written) implementation of tmpnam that does use the PID + increasing number and does a stat
check "does this file exist - if yes, increment the number and recheck), but that's possibly overkill.
from winflexbison.
I encountered this problem when trying to use this win_bison to build Wireshark in GitHub Actions. Wireshark has a CMake macro that expands to include ADD_CUSTOM_COMMAND
to invoke win_bison. There are about 16 *.l
files in wireshark (3.6 branch) and evidently the build system decides to build more than one concurrently.
https://github.com/objectcomputing/OpenDDS/runs/5160933295?check_suite_focus=true#step:10:2146
from winflexbison.
I had to give up winflexbison because of this issue ...
from winflexbison.
I had to give up winflexbison because of this issue ...
So you know use the windows binaries from MSYS2?
from winflexbison.
I had to give up winflexbison because of this issue ...
So you know use the windows binaries from MSYS2?
Yes. I wanted to generate reentrant scanners and for that I needed a newer version of Flex on Windows. But in the end, I will use a mutex on my side.
from winflexbison.
I was hitting this issue recently when I transition my project to Ninja build, I've added some debug information and saw their _tempnam-then-fopen time to be very close, this failure is more apparent on flex_temp_out_main
compared to the rest - temp_file_names
, meanwhile bison's m4
files rarely fails due to the close proximity of _tempname-then-fopen and when we specify a target location (cmake's WORKING_DIRECTORY
) for the bison execution, the temp files are generated in their respective target locations hence clashing is less likely...
Seems like this issue is only occurring on Windows despite having almost similar flow with Linux, I'm guessing its down to their file system implementations, Windows' delete reflects immediately in the file allocation, where as Linux files are inode-based where a file will only be deleted properly when link/use count is down to zero so a double delete doesn't really matter.
from winflexbison.
Thank you for sharing the note, so it is actually really old code (a" local" modification" which isn't upstream) that is the root for the issue. The following old commit provides the fix the issue f496d70 - if you can set FLEX_TEMP_DIR
, then still with 960f82d it is used.
Questions:
- Can you setup this in your build scripts?
- Can someone check how this is done upstream?
from winflexbison.
@GitMensch ,
It seems that _getpid
changes were removed (accidentally?) on the last sync from upstream - 960f82d
I've tried setting FLEX_TEMP_DIR
, it appears that Windows' _tempnam
totally ignores user-specified directory and the temporary file is always at %LocalAppData%\Temp
, so the issue still persist and is also the reason why all the flex instances are creating and writing to the same directory and ultimately same file occasionally due to race condition.
I'm using Windows 10, this _tempnam
might be an issue on newer Windows instead of all versions of Windows...
I have a quick read on upstream (not sure if there are intermediate upstreams apart from this), it seems to write directly to user's current working directory, eg. lex.yy.cc
, here is the code snippet:
if (!env.use_stdout) {
FILE *prev_stdout;
if (!env.did_outfilename) {
snprintf (outfile_path, sizeof(outfile_path), outfile_template,
ctrl.prefix, suffix());
env.outfilename = outfile_path;
}
prev_stdout = freopen (env.outfilename, "w+", stdout);
if (prev_stdout == NULL)
lerr (_("could not create %s"), env.outfilename);
outfile_created = 1;
}
Definitions:
static const char outfile_template[] = "lex.%s.%s";
ctrl.prefix = "yy";
const char *suffix (void)
{
const char *suffix;
if (is_default_backend()) {
if (ctrl.C_plus_plus)
suffix = "cc";
else
suffix = "c";
} else {
suffix = skel_property("M4_PROPERTY_SOURCE_SUFFIX");
}
return suffix;
}
Despite using Windows filesystem, the msys2 version is working fine, probably because every instance is isolated in its own working directory
from winflexbison.
@GitMensch ,
My mistake on calling it a _tempnam
bug, apparently MS documented the behavior, this function will ignore the directory if TMP
environment variable was set, and it is always set on all my machine to be LocalAppData\Temp
, and in all my other non-dev PCs (I can only confirm for Windows 10 and Windows 11)
This means FLEX_TEMP_DIR
never work, I think we should retire this variable too
from winflexbison.
@GitMensch ,
I've made a fix, lemme know if you're good with a PR
jonnysoe@dc0d204
from winflexbison.
@jonnysoe the code looks good to me in general and I'd like to see a PR with this. As noted in the comments to this commit we should drop the check for tmpnam == NULL
. Furthermore we should not duplicate the code but place it in the common directory along with appropriate header.
Feel free to send in 3 PRs:
1 - fix of this issue (and whitespace in the files touched)
2 - adding support for vscode
3 - the rest
from winflexbison.
Do I understand correctly that this isn't fixed yet for Windows?
Can't the name of the temporary file derived from the full filepath of the output file?
from winflexbison.
Related Issues (20)
- Bison-3.7.2 HOT 2
- v2.5.23 not working on Windows XP HOT 25
- Can not fix file via --update HOT 16
- Crash on invalid input HOT 6
- Visual Studio - win_bison creates tab.h file exceeding compiler limits HOT 8
- Update to bison 3.7.4 HOT 10
- Trouble compiling a *.l file using CMake HOT 7
- %option c++ is not compatible with %option noyywrap - linker error: multiple definition HOT 5
- Install guide lines? HOT 3
- Loss of data conversion in Flex scanner. HOT 5
- Update to Bison 3.8.1 HOT 11
- Missing LICENSE/COPYING file in repository toplevel HOT 6
- Cannot compile Bison input in C++ mode HOT 2
- Visual Studio dependencies and the provided CustomBuildRules HOT 3
- Could this project build with gcc HOT 2
- D language support fixes reported upstream
- Using api.prefix{ ... } breaks yyerror()
- Chocolatey for 2.5.25 (Bison 3.8) HOT 1
- BSD license and GPL license missing from the binary package
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from winflexbison.