move filewritable() into /src/os/fs.c and rename it

src/eval.c

@@ -8877,7 +8877,8 @@ static void f_filereadable(typval_T *argvars, typval_T *rettv)
  */
 static void f_filewritable(typval_T *argvars, typval_T *rettv)
 {
-  rettv->vval.v_number = filewritable(get_tv_string(&argvars[0]));
+  char *filename = (char *)get_tv_string(&argvars[0]);
+  rettv->vval.v_number = os_file_is_writable(filename);
 }
 
 static void findfilendir(typval_T *argvars, typval_T *rettv,

src/misc2.c

@@ -1666,33 +1666,6 @@ void sort_strings(char_u **files, int count)
   qsort((void *)files, (size_t)count, sizeof(char_u *), sort_compare);
 }
 
-/*
- * Return 0 for not writable, 1 for writable file, 2 for a dir which we have
- * rights to write into.
- */
-int filewritable(char_u *fname)
-{
-  int retval = 0;
-#if defined(UNIX) || defined(VMS)
-  int perm = 0;
-#endif
-
-#if defined(UNIX) || defined(VMS)
-  perm = os_getperm(fname);
-#endif
-  if (
-# if defined(UNIX) || defined(VMS)
-    (perm & 0222) &&
-#  endif
-    mch_access((char *)fname, W_OK) == 0
-    ) {
-    ++retval;
-    if (os_isdir(fname))
-      ++retval;
-  }
-  return retval;
-}
-
 /*
  * Print an error message with one or two "%s" and one or two string arguments.
  * This is not in message.c to avoid a warning for prototypes.

src/misc2.h

@@ -72,7 +72,6 @@ int vim_chdirfile(char_u *fname);
 int illegal_slash(char *name);
 int vim_chdir(char_u *new_dir);
 void sort_strings(char_u **files, int count);
-int filewritable(char_u *fname);
 int emsg3(char_u *s, char_u *a1, char_u *a2);
 int emsgn(char_u *s, long n);
 int get2c(FILE *fd);

src/os/fs.c

@@ -288,3 +288,16 @@ int os_file_is_readonly(const char *name)
   }
 }
 
+// return 0 for not writable, 1 for writable file, 2 for a dir which we have
+// rights to write into.
+int os_file_is_writable(const char *name)
+{
+  if (mch_access(name, W_OK) == 0) {
+    if (os_isdir((char_u *)name)) {
+      return 2;
+    }
+    return 1;
+  }
+  return 0;
+}
+

src/os/os.h

@@ -69,5 +69,6 @@ int os_get_user_name(char *s, size_t len);
 int os_get_uname(uid_t uid, char *s, size_t len);
 char *os_get_user_directory(const char *name);
 int os_file_is_readonly(const char *name);
+int os_file_is_writable(const char *name);
 
 #endif  // NEOVIM_OS_OS_H

src/spell.c

@@ -8585,7 +8585,7 @@ static void init_spellfile(void)
       else
         /* Copy the path from 'runtimepath' to buf[]. */
         copy_option_part(&rtp, buf, MAXPATHL, ",");
-      if (filewritable(buf) == 2) {
+      if (os_file_is_writable((char *)buf) == 2) {
         /* Use the first language name from 'spelllang' and the
          * encoding used in the first loaded .spl file. */
         if (aspath)
@@ -8595,7 +8595,7 @@ static void init_spellfile(void)
           /* Create the "spell" directory if it doesn't exist yet. */
           l = (int)STRLEN(buf);
           vim_snprintf((char *)buf + l, MAXPATHL - l, "/spell");
-          if (filewritable(buf) != 2)
+          if (os_file_is_writable((char *)buf) != 2)
             vim_mkdir(buf, 0755);
 
           l = (int)STRLEN(buf);

test/unit/os/fs.moon

@@ -20,6 +20,7 @@ int32_t os_getperm(char_u *name);
 int os_setperm(char_u *name, long perm);
 int os_file_exists(const char_u *name);
 int os_file_is_readonly(char *fname);
+int os_file_is_writable(const char *name);
 ]]
 
 -- import constants parsed by ffi
@@ -286,6 +287,9 @@ describe 'fs function', ->
     os_file_is_readonly = (filename) ->
       fs.os_file_is_readonly (to_cstr filename)
 
+    os_file_is_writable = (filename) ->
+      fs.os_file_is_writable (to_cstr filename)
+
     bit_set = (number, check_bit) ->
       if 0 == (bit.band number, check_bit) then false else true
 
@@ -340,6 +344,23 @@ describe 'fs function', ->
       it 'returns FALSE if the file is writable', ->
         eq FALSE, os_file_is_readonly 'unit-test-directory/test.file'
 
+    describe 'os_file_is_writable', ->
+      it 'returns FALSE if the file is readonly', ->
+        perm = os_getperm 'unit-test-directory/test.file'
+        perm_orig = perm
+        perm = unset_bit perm, ffi.C.kS_IWUSR
+        perm = unset_bit perm, ffi.C.kS_IWGRP
+        perm = unset_bit perm, ffi.C.kS_IWOTH
+        eq OK, (os_setperm 'unit-test-directory/test.file', perm)
+        eq FALSE, os_file_is_writable 'unit-test-directory/test.file'
+        eq OK, (os_setperm 'unit-test-directory/test.file', perm_orig)
+
+      it 'returns TRUE if the file is writable', ->
+        eq TRUE, os_file_is_writable 'unit-test-directory/test.file'
+
+      it 'returns 2 when given a folder with rights to write into', ->
+        eq 2, os_file_is_writable 'unit-test-directory'
+
   describe 'os_file_exists', ->
     os_file_exists = (filename) ->
       fs.os_file_exists (to_cstr filename)