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Top Forums Programming Can't debug: assert error with gdb (no problem without) Post 302755723 by erupter on Monday 14th of January 2013 10:52:06 AM
Old 01-14-2013
I managed to understand an important detail:

the problem arises from how I pass parameters to the child thread.

If I just pass a void pointer to the zmq context, all is fine.
If I pass a pointer to my struct (with explicit castings on both sides), the problems shows its head.

Now I don't know enough to understand this, I hope someone more knowledgeable can chime in.

Here are the two possibilities

working
Code:
void *zmq_cont_ptr = zmq_ctx_new();
pthread_create(&th_hndl_subber, NULL, th_subscriber, zmq_cont_ptr);

non working
Code:
typedef struct parameters{
    //Zmqcpp::Context * zmqcont;
    void * zmqcont;
    void (*callback) (std::string);
    std::string ip;
    int conntype;
    std::list<std::string> topics;
}parameters;

parameters myparams;

pthread_create(&th_hndl_subber, NULL, th_subscriber, (void *)&myparams);

void * th_subscriber(void * parameters)
{
    parameters *myparams = (parameters *) params;

---------- Post updated at 04:52 PM ---------- Previous update was at 01:52 PM ----------

I finally know what's the problem!!!
Thanks to chaingun from IRC channel #programming on FreeNode!

The problem is how long a temporary buffer lasts in memory.
As he pointed out when I pass something like
Code:
std::string mystring = "something";
myfunc(mystring.c_str());

A temporary buffer is allocated for the array of chars, but there are no guarantees on how much it will last.
That was the problem because when I moved the parameters into const char arrays, I was able to both run and debug the program.

Thank you to all who took the time to read this!
This User Gave Thanks to erupter For This Post:
 

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GZEXE(1)						      General Commands Manual							  GZEXE(1)

NAME
gzexe - compress executable files in place SYNOPSIS
gzexe name ... DESCRIPTION
The gzexe utility allows you to compress executables in place and have them automatically uncompress and execute when you run them (at a penalty in performance). For example if you execute ``gzexe /usr/bin/gdb'' it will create the following two files: -rwxr-xr-x 1 root root 1026675 Jun 7 13:53 /usr/bin/gdb -rwxr-xr-x 1 root root 2304524 May 30 13:02 /usr/bin/gdb~ /usr/bin/gdb~ is the original file and /usr/bin/gdb is the self-uncompressing executable file. You can remove /usr/bin/gdb~ once you are sure that /usr/bin/gdb works properly. This utility is most useful on systems with very small disks. OPTIONS
-d Decompress the given executables instead of compressing them. SEE ALSO
gzip(1), znew(1), zmore(1), zcmp(1), zforce(1) CAVEATS
The compressed executable is a shell script. This may create some security holes. In particular, the compressed executable relies on the PATH environment variable to find gzip and some standard utilities (basename, chmod, ln, mkdir, mktemp, rm, sleep, and tail). BUGS
gzexe attempts to retain the original file attributes on the compressed executable, but you may have to fix them manually in some cases, using chmod or chown. GZEXE(1)
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