[RFC] new substitute path when loading feature

[Aleksandar Ristovski]

Hello,

For us who deal with mixed-platform development environment it is common to debug binaries built on a different machine, often different OS. A real-life example:

development environment (sdk) is setup on a win32 machine, with headers and all. When compiled, binaries are being debugged on a linux-hosted gdb. Linux machine has the same development environment (sdk) only in different root directories. Where win32 may have C:/foo, linux will have /opt/foo, etc...

To properly translate the paths it is useful to be able to tell gdb to translate such paths into new environment. Existing "substitute-path" functionality seems like the most logical choice, and the diff exploits this to add new feature - rewriting source paths at readin time.

The difference can be observed if a binary built on a win32 system is loaded in gdb on linux. For example  
(gdb) maint info symtabs
....
{ symtab C:/QNX632/target/qnx6/usr/include/sys/compiler_gnu.h
    ((struct symtab *) 0x8390808)
    dirname c:/Temp/dirs/debug
    fullname (null)
    blockvector ((struct blockvector *) 0x8392f24)
    linetable ((struct linetable *) (nil))
    debugformat unknown
  }
  { symtab ../main.c ((struct symtab *) 0x83907b0)
    dirname c:/Temp/dirs/debug
    fullname (null)
    blockvector ((struct blockvector *) 0x8392f24) (primary)
    linetable ((struct linetable *) 0x8392f9c)
    debugformat DWARF 2
  }
...
while with the patch:
(gdb) set substitute-path-at-source 1
(gdb) set substitute-path C:/QNX632 /opt/qnx632
(gdb) set substitute-path c:/Temp /tmp
(gdb) symbol-file /tmp/dirs/debug/main
Load new symbol table from "/tmp/dirs/debug/main"? (y or n) y
Reading symbols from /tmp/dirs/debug/main...done.
(gdb) maint info symtabs
....
  { symtab /opt/qnx632/target/qnx6/usr/include/sys/compiler_gnu.h
    ((struct symtab *) 0x8379c10)
    dirname /tmp/dirs/debug
    fullname (null)
    blockvector ((struct blockvector *) 0x837c32c)
    linetable ((struct linetable *) (nil))
    debugformat unknown
  }
  { symtab ../main.c ((struct symtab *) 0x8379bb8)
    dirname /tmp/dirs/debug
    fullname (null)
    blockvector ((struct blockvector *) 0x837c32c) (primary)
    linetable ((struct linetable *) 0x837c390)
    debugformat DWARF 2
  }
...


Thanks,

Aleksandar Ristovski
QNX Software Systems

ChangeLog:

2008-05-13  Aleksandar Ristovski  <aristovski@qnx.com>

	* Makefile.in (buildsym.o): Add new dependency.
	* buildsym.c (source.h): New include.
	(start_subfile): Rewrite path is substitute-path-at-source is set.
	* source.c (substitute_pat_at_source): New variable.
	(rewrite_source_path): Make external.
	(_initialize_source): Add new set/show variable 
	'substitute-path-at-source'.
	* source.h (rewrite_source_path substitute_pat_at_source): New 
	declarations.
	* symfile.c (start_psymtab_common): Rewrite file name if 
	substitute-path-at-source is set.
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