[lldb-dev] Do we have any infrastructure for creating mini dump files from a loaded process or from a core file?

[Zachary Turner via lldb-dev]

Yea, I think something like this would actually make a useful llvm
utility.  Call it llvm-core or something, and it links against the library
LLVMCoreFile.  We could move all the code for consuming and producing
Windows minidumps and Unix / Mach-O corefiles from LLDB down into
LLVMCoreFile, write a library like llvm-core that can manipulate or inspect
them, then have LLDB use it.  Kill 2 birds with one stone that way IMO.

On Wed, Jun 13, 2018 at 2:56 PM Jason Molenda <jmolenda at apple.com> wrote:

> fwiw I had to prototype a new LC_NOTE load command a year ago in Mach-O
> core files, to specify where the kernel binary was located.  I wrote a
> utility to add the data to an existing corefile - both load command and
> payload - and it was only about five hundred lines of C++.  I didn't link
> against anything but libc, it's such  a simple task I didn't sweat trying
> to find an object-file-reader/writer library.  ELF may be more complicated
> though.
>
> > On Jun 13, 2018, at 2:51 PM, Zachary Turner via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
> >
> > What about the case where you already have a Unix core file and you
> aren't in a debugger but just want to convert it?  It seems like we could
> have a standalone utility that did that (one could imagine doing the
> reverse too).  I'm wondering if it wouldn't be possible to do this as a
> library or something that didn't have any dependencies on LLDB, that way a
> standalone tool could link against this library, and so could LLDB.  I
> think this would improve its usefulness quite a bit.
> >
> > On Wed, Jun 13, 2018 at 2:42 PM Greg Clayton <clayborg at gmail.com> wrote:
> > The goal is to take a live process (regular process just stopped, or a
> core file) and run "save_minidump ..." as a command and export a minidump
> file that can be sent elsewhere. Unix core files are too large to always
> send and they are less useful if they are not examined in the machine that
> they were produced on. So LLDB gives us the connection to the live process,
> and we can then create a minidump file. I am going to create a python
> module that can do this for us.
> >
> > Greg
> >
> >
> >> On Jun 13, 2018, at 2:29 PM, Zachary Turner via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
> >>
> >> Also, if the goal is to have this upstream somewhere, it would be nice
> to have a tool this be a standalone tool.  This seems like something that
> you shouldn't be required to start up a debugger to do, and probably
> doesn't have many (or any for that matters) on the rest of LLDB.
> >>
> >> On Wed, Jun 13, 2018 at 1:58 PM Leonard Mosescu <mosescu at google.com>
> wrote:
> >> That being said, it's not exactly trivial to produce a good minidump.
> Crashpad has a native & cross-platform minidump writer, that's what I'd
> start with.
> >>
> >> Addendum: I realized after sending the email that if the goal is to
> convert core files -> LLDB -> minidump a lot of the complexity found in
> Crashpad can be avoided, so perhaps writing an LLDB minidump writer from
> scratch would not be too bad.
> >>
> >> On Wed, Jun 13, 2018 at 1:50 PM, Leonard Mosescu <mosescu at google.com>
> wrote:
> >> The minidump format is more or less documented in MSDN.
> >>
> >> That being said, it's not exactly trivial to produce a good minidump.
> Crashpad has a native & cross-platform minidump writer, that's what I'd
> start with.
> >>
> >> On Wed, Jun 13, 2018 at 1:38 PM, Adrian McCarthy via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
> >> Zach's right.  On Windows, lldb can produce a minidump, but it just
> calls out to a Microsoft library to do so.  We don't have any
> platform-agnostic code for producing a minidump.
> >>
> >> I've also pinged another Googler who I know might be interested in
> converting between minidumps and core files (the opposite direction) to see
> if he has any additional info.  I don't think he's on lldb-dev, though, so
> I'll act as a relay if necessary.
> >>
> >> On Wed, Jun 13, 2018 at 12:07 PM, Zachary Turner via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
> >> We can’t produce them, but you should check out the source code of
> google breakpad / crashpad which can.
> >>
> >> That said it’s a pretty simple format, there may be enough in our
> consumer code that should allow you to produce them
> >>
> >>
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