Skip to content

Latest commit

 

History

History
23 lines (19 loc) · 2.93 KB

TODO.md

File metadata and controls

23 lines (19 loc) · 2.93 KB
Raw

TODO:

  • Build system:
    • Doctoc for README(s).
    • Placeholders for project and script name.
  • GDB test-run: dylib version errors, etc.
  • Document debug requirement.
  • Interpolation of longmess so as not to need Carp?
  • Enable/disable C backtrace.
  • Tests.
  • Thread support.
  • Execute code from commandline or from file.
  • Look into Devel::GDB.
  • Better OSX support (lldb?)

Why is it written in Go, not Perl?

gdb-inject-perl was written in Perl eventually (and that version can still be used; it's in the legacy-pure-perl subdirectory of the source repository). So why the switch? A few reasons:

  • Static Linking/Runtime Dependencies. Running the compiled Go version of gdb-inject-perl doesn't require Perl, Go, or any preinstalled software other than libc. If that seems pointless, consider the use case of debugging an embedded Perl interpreter (e.g. in mod_perl or similar) on a system that does not have a compatible or usable installation of the perl commandline utility. Systems without commandline Perls are admittedly rare, but also consider that some systems may not have Perl easily locatable on the PATH, and that different versions of Perl make different runtime assumptions and support different features, and that commandline-Perl may often be severely outdated, or custom-compiled for a system. While trying to get emergency debugging information from an embedded, opaque Perl process, having to stop and deal with the vagaries of operating system package configuration is far from ideal.
    • A commandline Perl interpreter is still required for testing custom --code values being injected. Testing can, however, be bypassed with the --force switch.
  • Library Dependencies. The pure-Perl version had several CPAN modules as dependencies. For some users, installing CPAN modules in order to use a last-ditch debugging tool may take too much time, be out of the user's expertise level, or not be supported when running as the root user (which is required in order to use this script). Since Go is compiled and statically linked, it should be dependecy-free; even though third-party dependencies are used in the source code, end users don't have to remember to install them, provided they are running the version of gdb-inject-perl written for thier operating system.
  • Concurrency. Even though gdb-inject-perl is very simple, it still needs low-level access to pipes, and needs to simultaneously wait for timeouts, user signals, or output from the process being inspected. This is totally possible in Perl, but, due to Perl's single-threaded nature and default buffering, requires careful coding around sysread and select, or the installation of additional CPAN dependencies. The implementation in the pure-Perl version of gdb-inject-perl is far from perfect, and is still nearly a hundred lines of relatively esoteric code. Go suports multiplexed event waiting by default, and also has more powerful standard-library facilities for dealing with pipes.