CODEWITHSUNDEEP
cmultithreadingglibc
longbowk
longbowk

Reputation: 229

Where can I find the list of non-reentrant functions provided in gnu libc?

I am now porting an single-threaded library to support multi-threads, and I need the whole list of functions that use local static or global variables.

Any information is appreciated.

Upvotes: 2

Views: 2472

Answers (2)

Jim Balter
Jim Balter

Reputation: 16406

Check the manual page for each function you use ... the non-thread-safe ones will be identified as such, and the manual page will mention a thread safe version when there is one (e.g., readdir_r). You could extract the list by running a script over the man pages.

Edit: Although my answer has been accepted, I fear that it is inaccurate and possibly dangerous. For example, while strerror_r mentions that it is a thread safe version of strerror, strerror itself says nothing about thread safety ... what it says instead is "the string might be overwritten", which merely implies that it isn't thread-safe. So you need to search for at least "might be overwritten" as well as "thread", but there's no guarantee that even that will be complete.

Upvotes: 2

Brady
Brady

Reputation: 10357

Its always a good idea to know if a particular function is reentrant or not, but you must also consider the situation when you may call several reentrant functions from a shared piece of code from multiple threads, which could also lead to problems when using shared data.

So, if you have any data shared between threads, the data must be "protected" irregardless of the fact that the functions being called are reentrant.

Consider the following function:

void yourFunc(CommonObject *o)
{
    /* This function is NOT thread safe */
    reentrant_func1(o->propertyA);
    reentrant_func2(o->propertyA);
}

If this function is not mutex protected, you will get undesired behavior in a multithreaded application, irregardless of the fact that func1 and func2 are reentrant.

Upvotes: 1

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