Moved mch_get_pid and renamed it to os_get_pid

src/eval.c

@@ -9872,7 +9872,7 @@ static void f_getmatches(typval_T *argvars, typval_T *rettv)
  */
 static void f_getpid(typval_T *argvars, typval_T *rettv)
 {
-  rettv->vval.v_number = mch_get_pid();
+  rettv->vval.v_number = os_get_pid();
 }
 
 /*

src/fileio.c

@@ -5730,7 +5730,7 @@ vim_tempname (
          * unlikely that it already exists it will be faster,
          * otherwise it doesn't matter.  The use of mkdir() avoids any
          * security problems because of the predictable number. */
-        nr = (mch_get_pid() + (long)time(NULL)) % 1000000L;
+        nr = (os_get_pid() + (long)time(NULL)) % 1000000L;
         itmplen = STRLEN(itmp);
 
         /* Try up to 10000 different values until we find a name that

src/memline.c

@@ -347,7 +347,7 @@ int ml_open(buf_T *buf)
     b0p->b0_uname[B0_UNAME_SIZE - 1] = NUL;
     mch_get_host_name(b0p->b0_hname, B0_HNAME_SIZE);
     b0p->b0_hname[B0_HNAME_SIZE - 1] = NUL;
-    long_to_char(mch_get_pid(), b0p->b0_pid);
+    long_to_char(os_get_pid(), b0p->b0_pid);
     if (*buf->b_p_key != NUL)
       ml_set_b0_crypt(buf, b0p);
   }

src/os/env.c

@@ -50,3 +50,13 @@ char *os_getenvname_at_index(size_t index)
 # endif
 }
 
+
+long os_get_pid()
+{
+#ifdef _WIN32
+  return (long)GetCurrentProcessId();
+#else
+  return (long)getpid();
+#endif
+}
+

src/os/os.h

@@ -82,6 +82,11 @@ long_u os_total_mem(int special);
 const char *os_getenv(const char *name);
 int os_setenv(const char *name, const char *value, int overwrite);
 char *os_getenvname_at_index(size_t index);
+
+/// Get the process ID of the Neovim process.
+///
+/// @return the process ID.
+long os_get_pid(void);
 int os_get_usernames(garray_T *usernames);
 int os_get_user_name(char *s, size_t len);
 int os_get_uname(uid_t uid, char *s, size_t len);

src/os_unix.c

@@ -424,14 +424,6 @@ void mch_get_host_name(char_u *s, int len)
 }
 #endif /* HAVE_SYS_UTSNAME_H */
 
-/*
- * return process ID
- */
-long mch_get_pid()
-{
-  return (long)getpid();
-}
-
 #if defined(USE_FNAME_CASE) || defined(PROTO)
 /*
  * Set the case of the file name, if it already exists.  This will cause the

src/os_unix.h

@@ -20,7 +20,6 @@ int vim_is_iris(char_u *name);
 int vim_is_vt300(char_u *name);
 int vim_is_fastterm(char_u *name);
 void mch_get_host_name(char_u *s, int len);
-long mch_get_pid(void);
 void slash_adjust(char_u *p);
 void fname_case(char_u *name, int len);
 void mch_copy_sec(char_u *from_file, char_u *to_file);

src/quickfix.c

@@ -2605,7 +2605,7 @@ static char_u *get_mef_name(void)
   /* Keep trying until the name doesn't exist yet. */
   for (;; ) {
     if (start == -1)
-      start = mch_get_pid();
+      start = os_get_pid();
     else
       off += 19;
 

test/unit/os/env.moon

@@ -8,6 +8,7 @@ ffi.cdef [[
 const char *os_getenv(const char *name);
 int os_setenv(const char *name, const char *value, int override);
 char *os_getenvname_at_index(size_t index);
+long os_get_pid(void);
 ]]
 
 NULL = ffi.cast 'void*', 0
@@ -90,3 +91,16 @@ describe 'env function', ->
         maxuint64 = ffi.new 'size_t', 18446744073709000000
         eq NULL, env.os_getenvname_at_index maxuint64
 
+  describe 'os_get_pid', ->
+
+    it 'returns the process ID', ->
+      stat_file = io.open '/proc/self/stat'
+      if stat_file
+        stat_str = stat_file\read '*l'
+        stat_file\close!
+        pid = tonumber (stat_str\match '%d+')
+        eq pid, tonumber env.os_get_pid!
+      else
+        -- /proc is not avaliable on all systems, test if pid is nonzero.
+        eq true, (env.os_get_pid! > 0)
+