What is a good way to dump a Linux core file from inside a process?

Question

We have a server (written in C and C++) that currently catches a SEGV and dumps some internal info to a file. I would like to generate a core file and write it to disk at th

Answer 1

Google has a library for generating coredumps from inside a running process called google-coredumper. This should ignore ulimit and other mechanisms.

The documentation for the call that generates the core file is here. According to the documentation, it seems that it is feasible to generate a core file in a signal handler, though it is not guaranteed to always work.

Answer 2

You can also change the ulimit() from within your program with setrlimit(2). Like the ulimit shell command, this can lower limits, or raise them as hard as the hard limit allows. At startup setrlimit() to allow core dumping, and you're fine.

Answer 3

I assume you have a signal handler that catches SEGV, for example, and does something like print a message and call _exit(). (Otherwise, you'd have a core file in the first place!) You could do something like the following.

void my_handler(int sig)
{
   ...
   if (wantCore_ && !fork()) {
      setrlimit(...);  // ulimit -Sc unlimited
      sigset(sig, SIG_DFL);  // reset default handler
      raise(sig);  // doesn't return, generates a core file
   }
   _exit(1);
}

Answer 4

system ("kill -6 ")

I'd give it a try if you are still looking for something

Answer 5

use backtrace and backtrace_symbols glibc calls to get the trace, just keep in mind that backtrace_symbols uses malloc internally and in case of heap corruption it might fail.

Answer 6

Try using the Linux command gcore

usage: gcore [-o filename] pid

You'll need to use system (or exec) and getpid() to build up the right command line to call it from within your process