-----------------------------------------------
How to build and install the package -- src.rpm
-----------------------------------------------

a) Download the gencore-0.1-0.src.rpm
b) Rebuild the src.rpm using the following command:
	rpmbuild --rebuild gencore-0.1-0.src.rpm
c) In the rpmbuild folder created install the RPMs in RPMS folder
   through the following command:
	rpm -ivh gencore-0.1-0.x86_64.rpm gencore-debuginfo-0.1-0.x86_64.rpm libgencore-0.1-0.x86_64.rpm libgencore-devel-0.1-0.x86_64.rpm
c) The library and executables will be installed in /usr/bin
   and /usr/lib64 and the daemon will be started automatically.

----------------------------------------------
How to build and install the package -- tar.gz
----------------------------------------------

a) Untar it firstly
b) ./autoreconf --force --install
c) ./configure --prefix="path"
d) make
e) make install

The executable the the client libraries are installed in the path specified by
the user.

--------------------------------
Command Line Arguments - gencore
--------------------------------

We can call the gencore command in two ways.
a) gencore pid [output-file-name]
b) gencore --daemon 
   -- Creates a daemon, for aiding selfdumps.
c) gencore --socket
   -- Post installation, systemd will create the socket and listen for connections.
      Once a process requests a selfdump, the service will be spawned to handle
      the request. For this we need to have the correct version of systemd which
      has this socket option enabled.

In the first case, gencore performs a third party dump and we can specify the
PID of the process to be dumped. The output-filename is optional. If not 
specified, by default the core filename is core.pid and it is created in the CWD.

In the second case, we start a daemon and we wait for requests from processes
which requires a self dump. This daemon keeping waiting for such requests.
It can handle multiple requests for the dump. This method was adapted from the
CRIU self dump application.

A process which wants a dump, uses the libgencore library and calls the function
gencore(char *corefile).

----------------------------------
libgencore - gencore() -- selfdump
----------------------------------

A program can request a dump of itself. Such a dump is known as a self dump.
This can be done by using the library libgencore and calling the function
gencore(char *corefile).

For a selfdump, we need to first start gencore --daemon like mentioned before.
This daemon waits for requests for dumps. This is already done post installation.

Then in the process, which requests for a dump, we need to call the function 
gencore(char *absolute/relative pathname);

We use libgencore library to set up this interface.

eg. test.c

#include <dlfcn.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>

int (*gencore)(char *name);

void segv_handler(int signo)
{
	int ret;

	ret = gencore("/home/janani/demo/test_core");

	fprintf(stderr, "Status of dump: %s\n", strerror(ret)); 	
}
	
int main ()
{
	void *lib;

	signal(SIGSEGV, segv_handler);
	
	/* Opening the library, in this case the library is present in the /usr/lib64 */
	lib = dlopen("libgencore.so", RTLD_LAZY);

	gencore = dlsym(lib, "gencore");

	sleep(100);

	return 0;
}

-------
AUTHORS
-------

Janani Venkataraman <jananive@in.ibm.com>