Define _DEFAULT_SOURCE for syscall and realpath

[tiran]

Define _DEFAULT_SOURCE in random.c and alloc.c. The macro
is required for syscall() and realpath(). Other files like
os.c already define the macro.

Signed-off-by: Christian Heimes christian@python.org

[tiran]

The changes are required to vendor latest mimalloc with CPython. Without the changes I'm getting

Objects/mimalloc/random.c: In function ‘os_random_buf’:
Objects/mimalloc/random.c:215:19: error: implicit declaration of function ‘syscall’ [-Werror=implicit-function-declaration]
  215 |     ssize_t ret = syscall(SYS_getrandom, buf, buf_len, GRND_NONBLOCK);
      |                   ^~~~~~~
cc1: some warnings being treated as errors
make: *** [Makefile:1987: Objects/mimalloc/random.o] Error 1
make: *** Waiting for unfinished jobs....
Objects/mimalloc/alloc.c: In function ‘mi_heap_realpath’:
Objects/mimalloc/alloc.c:763:12: error: implicit declaration of function ‘realpath’; did you mean ‘mi_realpath’? [-Werror=implicit-function-declaration]
  763 |     return realpath(fname,resolved_name);
      |            ^~~~~~~~
      |            mi_realpath
Objects/mimalloc/alloc.c:763:12: warning: returning ‘int’ from a function with return type ‘char *’ makes pointer from integer without a cast [-Wint-conversion]
  763 |     return realpath(fname,resolved_name);
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Objects/mimalloc/alloc.c:769:20: warning: initialization of ‘char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
  769 |     char* rname  = realpath(fname,buf);
      |                    ^~~~~~~~

[daanx]

Thanks! I may move the definitions to mimalloc-internal.h instead later on. (Currently reading up about _DEFAULT_SOURCE and if it the right thing to do or not).

[tiran]

You are welcome!

The man pages for syscall and realpath lists the required macros to enable features:

       realpath():
           _XOPEN_SOURCE >= 500
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE

and

       syscall():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           Before glibc 2.19:
               _BSD_SOURCE || _SVID_SOURCE