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This is a follow up to my pretty function tracing article. I base this work on the code presented there.
Some one asked me how to get the gcc -finstrument-functions feature working. If you don't know this
flag will modify the entry and exit to/from each function to make a call out to a special set of functions used
for tracing.
While I've read about this feature, I never actually tried it. So here is what I learned...
I was squashing some warnings in uzbl code:
printf("set %s = %d\n", (char *)k, (int)*c->ptr);
Ignoring the fact that, at first glance, it's weird to cast a pointer to int
(ptr is defined as void**), compiling this code on 64bit would warn you
that you were casting a pointer to an int. That's because a pointer is 64bit
and an int is 32bit.
I've look around for an open source implementation of popen() that can handle redirection of
stdin, stdout, and stderr of the program executed. I was unable to find one, so I wrote
my own.
If you need to fork a helper process and maintain bidirectional communication wtih it, then you can use my popenRWE() (source: popenRWE.c.
Here is an example of how it might be used:
int pipe[3];
int pid;
const char *const args[] = {
"cat",
"-n",
NULL
};
pid = popenRWE(pipe, args[0], args);
// write to pipe[0] - input to cat
// read from pipe[1] - output from cat
// read from pipe[2] - errors from cat
pcloseRWE(pid, pipe);
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Thu May 17 06:27:42 2012
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