Re: [Tinycc-devel] env executable examples
Michael Matz wrote:
Hi,
On Thu, 10 May 2012, grischka wrote:
[1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85
Basically /usr/bin/env tcc -run will try to find tcc -run which is
then obviously not found. Should we go back to the solution proposed
in [2] or do you have another idea?
Why not use just
#!tcc -tun
Because shebangs are interpreted by the kernel VFS, which doesn't know
about $PATH, and hence won't find 'tcc' in any path (and therefore the
execution will fail). That's what env(1) was intended for, but the
linux kernel unfortunately supports only exactly one (optional) argument
for the interpreter, i.e. it breaks with two and more arguments like
when the shebang is #!env firstarg secondarg. So, all in all, when
you use an meta-interpreter (like env) that somehow needs the name of
the real interpreter as argument (tcc in this case) you can't give
further arguments to that real interpreter (-run here).
Ok, thanks. I'm finally able to understand now the deal with the
'expand_args' stuff here:
case TCC_OPTION_run:
{
int argc1;
char **argv1;
argc1 = expand_args(argv1, optarg);
if (argc1 0) {
parse_args(s, argc1, argv1);
}
multiple_files = 0;
output_type = TCC_OUTPUT_MEMORY;
break;
}
Otherwise I'd suggest to revert to the original
#!/usr/local/bin/tcc -tun
Which again would have the problem of hardcoding the path to tcc into
the scripts. You need a meta-interpreter for finding the name of the
real interpreter, and you can't give further arguments to it. Hence the
best suggestion up to now was to create a wrapper script called tcc-run
(just calling exec tcc -run $1 on its argument), which would be used
as argument to the 'env' shebang.
Of course, one could also decide to not care, but IMHO Davids above
suggestion (helper script) is the most satisfying one, given the sorry
circumstances.
Indeed it's sorry because my admittedly rather limited understanding
of shebang scripts is usage as simple as in
#!/usr/bin/perl
Now the examples ex1.c and ex4.c are meant to show off how tcc can be
used as an interpreter for C-scripts in a rather similar way, in
particular also with additional arguments such as in ex4.c:
#!/usr/local/bin/tcc -run -L/usr/X11R6/lib -lX11
Obviously the original intention (seen the 'expand_args' hack above)
is to make that possible without any additional wrapper script. The
point of the examples is to show that intention. If we provide a
wrapper script we would miss that point in the first place.
Also, if I'd install perl elsewhere, quite some things will stop to
work just as well. IMO it is not the point of our examples to show
how to escape from this system limitation.
My 2 cents.
--- grischka
Ciao,
Michael.
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[Tinycc-devel] env executable examples
Greetings everybody, I've just realized that the env trick to use tcc from the correct place [1] doesn't work because neither Linux nor env split arguments at spaces. [1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85 Basically /usr/bin/env tcc -run will try to find tcc -run which is then obviously not found. Should we go back to the solution proposed in [2] or do you have another idea? [2] cb2138f8b098feb1b51a407343a4b99e25d5b506 Best regards, Thomas Preud'homme signature.asc Description: This is a digitally signed message part. ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] env executable examples
Le jeudi 10 mai 2012 15:50:00, Thomas Preud'homme a écrit : Greetings everybody, I've just realized that the env trick to use tcc from the correct place [1] doesn't work because neither Linux nor env split arguments at spaces. [1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85 Basically /usr/bin/env tcc -run will try to find tcc -run which is then obviously not found. Should we go back to the solution proposed in [2] or do you have another idea? [2] cb2138f8b098feb1b51a407343a4b99e25d5b506 Best regards, Thomas Preud'homme Actually I've just realized another solution would be to search for a shebang to tcc when there is only one parameter and this is a c file. This way we could do /usr/bin/env tcc and tcc would know it must run the TCC_OUTPUT_MEMORY option. The problem would then be that a file starting with a valid shebang could not be compiled linked with tcc. It would break potential script doing tcc $file ./a.out What do you think? Best regards, Thomas Preud'homme signature.asc Description: This is a digitally signed message part. ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] env executable examples
Couldn't we just create the binary called tcc-run, so users could say #!/usr/bin/env tcc-run at the top of their files? On Thu, May 10, 2012 at 8:53 AM, Thomas Preud'homme robo...@celest.frwrote: Le jeudi 10 mai 2012 15:50:00, Thomas Preud'homme a écrit : Greetings everybody, I've just realized that the env trick to use tcc from the correct place [1] doesn't work because neither Linux nor env split arguments at spaces. [1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85 Basically /usr/bin/env tcc -run will try to find tcc -run which is then obviously not found. Should we go back to the solution proposed in [2] or do you have another idea? [2] cb2138f8b098feb1b51a407343a4b99e25d5b506 Best regards, Thomas Preud'homme Actually I've just realized another solution would be to search for a shebang to tcc when there is only one parameter and this is a c file. This way we could do /usr/bin/env tcc and tcc would know it must run the TCC_OUTPUT_MEMORY option. The problem would then be that a file starting with a valid shebang could not be compiled linked with tcc. It would break potential script doing tcc $file ./a.out What do you think? Best regards, Thomas Preud'homme ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel -- Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -- Brian Kernighan ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] env executable examples
Thomas Preud'homme wrote: Greetings everybody, I've just realized that the env trick to use tcc from the correct place [1] doesn't work because neither Linux nor env split arguments at spaces. [1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85 Basically /usr/bin/env tcc -run will try to find tcc -run which is then obviously not found. Should we go back to the solution proposed in [2] or do you have another idea? Why not use just #!tcc -tun Otherwise I'd suggest to revert to the original #!/usr/local/bin/tcc -tun which of course does not work if user installs tcc elsewhere but really we should not care. After all the examples are for studying purposes in the first place. --- grischka [2] cb2138f8b098feb1b51a407343a4b99e25d5b506 Best regards, Thomas Preud'homme ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] env executable examples
Hi, On Thu, 10 May 2012, grischka wrote: [1] See commit 27a428cd0fae475d7377e1dbe218c064ee217d85 Basically /usr/bin/env tcc -run will try to find tcc -run which is then obviously not found. Should we go back to the solution proposed in [2] or do you have another idea? Why not use just #!tcc -tun Because shebangs are interpreted by the kernel VFS, which doesn't know about $PATH, and hence won't find 'tcc' in any path (and therefore the execution will fail). That's what env(1) was intended for, but the linux kernel unfortunately supports only exactly one (optional) argument for the interpreter, i.e. it breaks with two and more arguments like when the shebang is #!env firstarg secondarg. So, all in all, when you use an meta-interpreter (like env) that somehow needs the name of the real interpreter as argument (tcc in this case) you can't give further arguments to that real interpreter (-run here). Otherwise I'd suggest to revert to the original #!/usr/local/bin/tcc -tun Which again would have the problem of hardcoding the path to tcc into the scripts. You need a meta-interpreter for finding the name of the real interpreter, and you can't give further arguments to it. Hence the best suggestion up to now was to create a wrapper script called tcc-run (just calling exec tcc -run $1 on its argument), which would be used as argument to the 'env' shebang. Of course, one could also decide to not care, but IMHO Davids above suggestion (helper script) is the most satisfying one, given the sorry circumstances. Ciao, Michael. ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
