Need info about the internals of printf

Need info about the internals of printf

[Eswar Chandra Tadikonda]

Hi,

I am going through the glibc source code cloned from the git repository. I
am quite interested on how the printf function works really under the code
to print the characters on display.

I actually got stuck at __vfprintf_internal function which i am not able to
find the definition through tags. BTW, is this the actual function called
internally by printf ?

Can you please help me on this code learning ?

Also please suggest me the right tools/method to traverse through the
source code...

Thanks,
Eswar

Re: Need info about the internals of printf

[Florian Weimer]

* Eswar Chandra Tadikonda:

> I actually got stuck at __vfprintf_internal function which i am not able to
> find the definition through tags.

Tags browsers generally do not work with the glibc sources due to heavy
use of the preprocessor, unfortunately.

stdio-common/vfprintf-internal.c has the implementation, and it contains
this:

#ifndef COMPILE_WPRINTF
# define vfprintf       __vfprintf_internal

So its vfprintf function is actually __vfprintf_internal.

> BTW, is this the actual function called internally by printf ?

Yes, calls eventually end up there.

Thanks,
Florian

Re: Need info about the internals of printf

[Konstantin Kharlamov]

В Вт, июн 18, 2019 at 00:02, Eswar Chandra Tadikonda 
<teswarsrinivas@gmail.com> написал:
> Hi,
> 
> I am going through the glibc source code cloned from the git 
> repository. I
> am quite interested on how the printf function works really under the 
> code
> to print the characters on display.
> 
> I actually got stuck at __vfprintf_internal function which i am not 
> able to
> find the definition through tags. BTW, is this the actual function 
> called
> internally by printf ?
> 
> Can you please help me on this code learning ?
> 
> Also please suggest me the right tools/method to traverse through the
> source code...

The reason you can't find is because universal ctags, etc, by default 
disable detecting some stuff. Per this question 
https://stackoverflow.com/q/3655743/2388257#when-using-exuberant-ctags-what-options-to-you-use 
you can use e.g.

	$ ctags --c-kinds=+defgpstux -R .

then, with universal ctags, I see the tag.