Hands-On System Programming with Linux

List of APIs not required to be thread-safe

The standard C library, glibc, has many older functions that, in the words of the Open Group manual, need not be thread-safe (or are not required to be thread-safe). All functions defined by this volume of POSIX.1-2017 shall be thread-safe, except that the following functions need not be thread-safe. What does that actually mean? Simple: these APIs are not thread-safe. So, be careful—do not use them in MT applications. The complete list can be found at: http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_09_01.

Of course, the preceding list is only valid as of POSIX.1-2017 and is bound to get outdated. The reader must be aware of this recurring issue, and the need to ...