minor edits for darwin host support

[kiwiroy]

overview

• use /bin/bash in shebang to allow echo -n
• readelf -s -> readelf --syms to allow gobjdump as substitute (see wrapper below)
• additional sed substitution to parse gobjdump output

motivation

When using /bin/sh, echo does not support the -n flag which results in it being printed along with the string with undesired effects. readelf needs to be replaced with gobjdump on Mac, but this doesn't support -s, but does allow --syms as readelf does. (readelf with gcc 6.4, macports barfs with "Error: Not an ELF file - it has the wrong magic bytes at the start" for try.o)

wrapper

I have a small wrapper called readelf in $PATH thus:

#!/bin/bash
exec gobjdump "$@"

And similar for objdump -> gobjdump and sed -> gsed.

[arsv]

#!/bin/bash has been changed to #!/bin/sh (and the code updated to run well with busybox sh and dash) some time ago to allow builds on Linux hosts that have no bash installed, and/or prefer not to use bash for this purpose. I'm pretty sure there are users who depend on this, too. Switching back to bash is not a good idea at this point.

If your build infrastructure allows it, patching that after unpacking perl-cross may be a better solution. Either sh -> bash, or maybe try to replace echo with printf if Darwin sh supports printf.

No objections to readelf changes if that's enough to get it working on Darwin. If you're ok with that, I'd apply the readelf parts of the patch only.

[kiwiroy]

@arsv sorry I wasn't aware /bin/sh was a fixed requirement. f3f08f6 switches to use env to achieve the same affect (untested on busybox).

[arsv]

Yeah but that would be a really weird thing to do in Linux. And dependency on env isn't really any better than dependency on echo -n.

Could you please check if the following fragment works correctly in Darwin? https://gist.github.com/arsv/18e6c930897275b378c427a2d6a81522

[kiwiroy]

That fragment works as expected.

[kiwiroy]

There's also the fragments here and here and the message in the latter

New applications are encouraged to use printf instead of echo.

There is also enable -n echo which will be in effect for the script and might be best in a case block. See bdbda87

case "$SHELL" in
  */bash)
    enable -n echo
    ;;
esac

[arsv]

Bash is not the problem, echo -n works just fine in bash. Pretty much anything would work in bash, including printf. The case should be between Darwin) and *) everything else, it's Darwin sh that needs special treatment for its lack of echo -n.

By the way, does printf work in Darwin shell?

[kiwiroy]

When sh is bash or is linked to bash it behaves like sh and or if certain shopt settings are set. There may be a version 3 vs 4 bash difference also, I don't have a Linux with bash v3 to confirm though. printf is available on Darwin.

[arsv]

Please take a look at https://github.com/arsv/perl-cross/tree/darwin and try it on Darwin is possible. I tweaked you commit a bit, if you're ok with that I'd merge it.

Only mstart actually needs no-newline printing. The other cases used echo -n > $file to truncate $file.

[kiwiroy]

@arsv ab8d05c is great. Thanks.

[arsv]

Ok, thanks, changes merged.