问题
I know _r suffix is used to indicate something thread-safe. For example strtok and strtok_r or libmysql.so and libmysql_r.so. But I cannot find anywhere what this actually means ? For example, _t means 'type' and what does _r suffix mean?
回答1:
See Chapter A.4.16 Thread-Safety in http://pubs.opengroup.org/onlinepubs/000095399/xrat/xbd_chap04.html:
The suffix "_r" is historical, where the 'r' stood for "reentrant".
回答2:
The _r suffix stands for reentrant.
回答3:
_r means reentrant, even though those functions may not be really reentrant. Those functions just guarantee not to use static storage.
来源：https://stackoverflow.com/questions/13103410/what-does-r-suffix-mean