code review 72280043: cmd/gc: replace '·' as '.' in ELF/Mach-O symbol tables

cmd/gc: replace '·' as '.' in ELF/Mach-O symbol tables

Old versions of DTrace (as those shipped in OS X and FreeBSD)
don't support unicode characters in symbol names.  Replace '·'
to '.' to make DTrace happy.

Fixes issue 7493

[aram, 2014-03-07 14:01:46]

Latest version is not good because it only handles ELF, which already works
pretty well with new Solaris kernel (albeit not FreeBSD kernels). The biggest
issue is with OS X kernel.

Do you want me to test the first version?

[aram, 2014-03-07 14:10:31]

> Do you want me to test the first version?

Nope, first version doesn't work:

  : iridium:aram; sudo dtrace -n 'pid$target:a.out::entry' -c `which go`
  [CoreSymbolication] In DWARF data from
kCSSymbolOwnerDataFaultedFromDisk, CSCppFileMemory
/Users/aram/bin/darwin/amd64/go:
    .debug_line[12227] file = 433 is not a valid index
  dtrace: invalid probe specifier pid$target:a.out::entry: failed to
create entry probe for 'main.init·1': Invalid argument
  : iridium:aram;
  : iridium:aram; /usr/bin/nm `which go` | grep 'main.init.1'
  0000000000002000 t main.init·1
  000000000004a440 t main.init·10
  0000000000051080 t main.init·11
  0000000000052110 t main.init·12
  : iridium:aram; cd go
  /Users/aram/go

  : iridium:go; hg st
  M src/cmd/gc/init.c
  M src/cmd/gc/pgen.c
  : iridium:go;

-- 
Aram Hăvărneanu

[minux1, 2014-03-07 16:16:34]

Aram, how about the latest patch set 6?
i also replace the middle dot in mach-o symbol table.

[aram, 2014-03-07 16:26:44]

Same problem:

iridium:src$ sudo dtrace -n 'pid$target:a.out::entry' -c `which go`
[CoreSymbolication] In DWARF data from kCSSymbolOwnerDataFaultedFromDisk,
CSCppFileMemory /Users/aram/bin/darwin/amd64/go:
  .debug_line[12227] file = 433 is not a valid index
dtrace: invalid probe specifier pid$target:a.out::entry: failed to create entry
probe for 'main.init·1': Invalid argument
iridium:src$ 
iridium:src$ 
iridium:src$ 
iridium:src$ 
iridium:src$ 
iridium:src$ /usr/bin/nm `which go` | grep 'main.init.1'
0000000000002000 t main.init·1
000000000004a440 t main.init·10
0000000000051080 t main.init·11
0000000000052110 t main.init·12

[aram, 2014-03-07 16:34:41]

Ah, no, sorry for the false alarm. I was running the wrong binary. This works on
OS X. Let me test on ELF too.

[aram, 2014-03-07 17:04:33]

Ok, so patch set 2 doesn't work on either ELF of Mach-O:
    failed to create entry probe for 'main.func·001': Invalid argument

Patch set 6 works on both ELF and Mach-O.

Sorry for the previous misinformation.

[aram, 2014-03-07 17:04:54]

LGTM

Please change description to:

cmd/gc: rename replace '·' with '.' in ELF/Mach-O symbol tables.
	
	Old versions of DTrace (as those shipped in OS X and FreeBSD)
	DTrace don't support unicode characters in symbol names.
	Replace '·' with '.' to make DTrace happy.
	
	Fixes issue 7493

https://codereview.appspot.com/72280043/diff/120001/src/cmd/ld/macho.c
File src/cmd/ld/macho.c (right):

https://codereview.appspot.com/72280043/diff/120001/src/cmd/ld/macho.c#newcod...
src/cmd/ld/macho.c:592: for (j=0; s->extname[j]!='\0'; j++) {
I'd write this with pointers but maybe that's just me.

[aram, 2014-03-07 17:05:38]

cmd/gc: rename replace '·' to '.' in ELF/Mach-O symbol tables.

	Old versions of DTrace (as those shipped in OS X and FreeBSD)
	don't support unicode characters in symbol names.  Replace '·'
	to '.' to make DTrace happy.

	Fixes issue 7493


Removed double DTrace.

[minux1, 2014-03-07 17:23:12]

Hello aram@mgk.ro (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go

[gobot, 2014-03-07 21:09:49]

R=rsc@golang.org (assigned by aram@mgk.ro)

[aram, 2014-03-07 21:10:34]

[+iant, rsc]

LGTM, leaving for rsc.

[rsc, 2014-03-13 02:20:38]

LGTM

[minux1, 2014-03-14 14:07:55]

*** Submitted as https://code.google.com/p/go/source/detail?r=c837a5edfd42 ***

cmd/gc: replace '·' as '.' in ELF/Mach-O symbol tables

Old versions of DTrace (as those shipped in OS X and FreeBSD)
don't support unicode characters in symbol names.  Replace '·'
to '.' to make DTrace happy.

Fixes issue 7493

LGTM=aram, rsc
R=aram, rsc, gobot, iant
CC=golang-codereviews
https://codereview.appspot.com/72280043