Add list of thread-safe functions.

man7/pthreads.7

@@ -106,6 +106,110 @@ capabilities (see
 .IP \- 3
 CPU affinity
 .RB ( sched_setaffinity (2))
+.SS "Thread-safe functions"
+A thread-safe function is one that can be safely
+(i.e., it will deliver the same results regardless of whether it is)
+called from multiple threads at the same time.
+
+POSIX.1-2001 requires that all functions specified in the standard
+shall be thread-safe, except for the following functions:
+.\" FIXME . SUSv4 removes ecvt(), fcvt(), gcvt(), gethostbyname(), and
+.\" gethostbyaddr(), since they are removed from the standard, and
+.\" and adds strerror() and system().
+.in +4n
+.nf
+
+asctime()
+basename()
+catgets()
+crypt()
+ctermid() if passed a non-NULL argument
+ctime()
+dbm_clearerr()
+dbm_close()
+dbm_delete()
+dbm_error()
+dbm_fetch()
+dbm_firstkey()
+dbm_nextkey()
+dbm_open()
+dbm_store()
+dirname()
+dlerror()
+drand48()
+ecvt()
+encrypt()
+endgrent()
+endpwent()
+endutxent()
+fcvt()
+ftw()
+gcvt()
+getc_unlocked()
+getchar_unlocked()
+getdate()
+getenv()
+getgrent()
+getgrgid()
+getgrnam()
+gethostbyaddr()
+gethostbyname()
+gethostent()
+getlogin()
+getnetbyaddr()
+getnetbyname()
+getnetent()
+getopt()
+getprotobyname()
+getprotobynumber()
+getprotoent()
+getpwent()
+getpwnam()
+getpwuid()
+getservbyname()
+getservbyport()
+getservent()
+getutxent()
+getutxid()
+getutxline()
+gmtime()
+hcreate()
+hdestroy()
+hsearch()
+inet_ntoa()
+l64a()
+lgamma()
+lgammaf()
+lgammal()
+localeconv()
+localtime()
+lrand48()
+mrand48()
+nftw()
+nl_langinfo()
+ptsname()
+putc_unlocked()
+putchar_unlocked()
+putenv()
+pututxline()
+rand()
+readdir()
+setenv()
+setgrent()
+setkey()
+setpwent()
+setutxent()
+strerror()
+strtok()
+tmpnam() if passed a non-NULL argument
+ttyname()
+unsetenv()
+wcrtomb() if its final argument is NULL
+wcsrtombs() if its final argument is NULL
+wcstombs()
+wctomb()
+.fi
+.in
 .SS "Compiling on Linux"
 On Linux, programs that use the Pthreads API should be compiled using
 .IR "cc \-pthread" .