Re: is $(file ) thread safe when using option -j ?

[Tim Murphy]

Sorry to butt in here but can I just point out that there is a crash in
$(file) when you don't give it anything to write.

--- a/function.c
+++ b/function.c
@@ -2156,14 +2156,25 @@ func_file (char *o, char **argv, const char
*funcname UN
         }
       else
         {
-          int l = strlen (argv[1]);
-          int nl = (l == 0 || argv[1][l-1] != '\n');
+          char *outstr = argv[1];
@@ -2156,14 +2156,25 @@ func_file (char *o, char **argv, const char
*funcname UN
         }
       else
         {
-          int l = strlen (argv[1]);
-          int nl = (l == 0 || argv[1][l-1] != '\n');
+          char *outstr = argv[1];
+          int l, nl;
+          if (outstr == NULL)
+            {
+              outstr="";
+              l = 0;
+              nl = 0;
+            }
+          else
+            {
+              l = strlen (outstr);
+              nl = (l == 0 || outstr[l-1] != '\n');
+            }

-          if (fputs (argv[1], fp) == EOF || (nl && fputc ('\n', fp) ==
EOF))
+          if (fputs (outstr, fp) == EOF || (nl && fputc ('\n', fp) == EOF))
             {



Cheers,


Tim

On 12 September 2014 19:18, Paul Smith <address@hidden> wrote:

> On Fri, 2014-09-12 at 17:43 +0200, Pierre Lindenbaum wrote:
> > when using $(file )
> > http://www.gnu.org/software/make/manual/make.html#File-Function .
> >
> > If two targets, built in parallel with option -j, both call
> >
> >      $(file >>log.txt, Building $@)
> >
> > is $file thead safe or is it possible to obtain a mixture of both
> > messages in the file log.txt ?
>
> GNU make is actually not multithreaded.  It will invoke subprocesses
> that run in parallel, but make itself does not use threads.
>
> This means that, as long as you are talking about a single make
> invocation, there is no way that multiple instances of file (or any
> other make function) will intermingle, and so the content above will
> never mix.
>
> If you use recursive make and two make processes are running at the same
> time via -j and both use $(file ...) to update the same file, then it's
> possible you'll get intermixing of content (but, as long as the length
> of the content is small, it's pretty unlikely due to the way the kernel
> handles write() system calls).
>
>
> _______________________________________________
> Help-make mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/help-make
>



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