win: os_get_hostname() #5416 (#6413)

src/nvim/mbyte.c

@@ -1304,6 +1304,7 @@ static int utf_strnicmp(const char_u *s1, const char_u *s2, size_t n1,
 # define CP_UTF8 65001  /* magic number from winnls.h */
 #endif
 
+/// Reassigns `strw` to a new, allocated pointer to a UTF16 string.
 int utf8_to_utf16(const char *str, WCHAR **strw)
   FUNC_ATTR_NONNULL_ALL
 {
@@ -1345,11 +1346,12 @@ int utf8_to_utf16(const char *str, WCHAR **strw)
   return 0;
 }
 
+/// Reassigns `str` to a new, allocated pointer to a UTF8 string.
 int utf16_to_utf8(const WCHAR *strw, char **str)
   FUNC_ATTR_NONNULL_ALL
 {
   // Compute the space required to store the string as UTF-8.
-  ssize_t utf8_len = WideCharToMultiByte(CP_UTF8,
+  DWORD utf8_len = WideCharToMultiByte(CP_UTF8,
                                        0,
                                        strw,
                                        -1,
@@ -1361,24 +1363,23 @@ int utf16_to_utf8(const WCHAR *strw, char **str)
     return GetLastError();
   }
 
-  ssize_t buf_sz = utf8_len * sizeof(char);
-  char *buf = xmalloc(buf_sz);
-  char *pos = buf;
+  *str = xmalloc(utf8_len);
 
-  // Convert string to UTF-8.
-  int r = WideCharToMultiByte(CP_UTF8,
+  // Convert to UTF-8.
+  utf8_len = WideCharToMultiByte(CP_UTF8,
                                  0,
                                  strw,
                                  -1,
-                              pos,
+                                 *str,
                                  utf8_len,
                                  NULL,
                                  NULL);
-  assert(r == utf8_len);
-  if (r != utf8_len) {
-    EMSG2("WideCharToMultiByte failed: %d", r);
+  if (utf8_len == 0) {
+    free(*str);
+    *str = NULL;
+    return GetLastError();
   }
-  *str = pos;
+  (*str)[utf8_len] = '\0';
 
   return 0;
 }

src/nvim/os/env.c

@@ -118,7 +118,6 @@ char *os_getenvname_at_index(size_t index)
   return name;
 }
 
-
 /// Get the process ID of the Neovim process.
 ///
 /// @return the process ID.
@@ -145,10 +144,27 @@ void os_get_hostname(char *hostname, size_t size)
   } else {
     xstrlcpy(hostname, vutsname.nodename, size);
   }
+#elif defined(WIN32)
+  WCHAR host_utf16[MAX_COMPUTERNAME_LENGTH + 1];
+  DWORD host_wsize = sizeof(host_utf16) / sizeof(host_utf16[0]);
+  if (GetComputerNameW(host_utf16, &host_wsize) == 0) {
+    *hostname = '\0';
+    DWORD err = GetLastError();
+    EMSG2("GetComputerNameW failed: %d", err);
+    return;
+  }
+  host_utf16[host_wsize] = '\0';
+
+  char *host_utf8;
+  int conversion_result = utf16_to_utf8(host_utf16, &host_utf8);
+  if (conversion_result != 0) {
+    EMSG2("utf16_to_utf8 failed: %d", conversion_result);
+    return;
+  }
+  xstrlcpy(hostname, host_utf8, size);
+  xfree(host_utf8);
 #else
-  // TODO(unknown): Implement this for windows.
-  // See the implementation used in vim:
-  // https://code.google.com/p/vim/source/browse/src/os_win32.c?r=6b69d8dde19e32909f4ee3a6337e6a2ecfbb6f72#2899
+  EMSG("os_get_hostname failed: missing uname()");
   *hostname = '\0';
 #endif
 }

src/nvim/os/fs.c

@@ -1009,7 +1009,7 @@ char *os_resolve_shortcut(const char *fname)
     WCHAR *p;
     const int conversion_result = utf8_to_utf16(fname, &p);
     if (conversion_result != 0) {
-      EMSG2("utf8_to_utf16 failed: %s", uv_strerror(conversion_result));
+      EMSG2("utf8_to_utf16 failed: %d", conversion_result);
     }
 
     if (p != NULL) {

test/functional/eval/hostname_spec.lua

@@ -0,0 +1,17 @@
+local helpers = require('test.functional.helpers')(after_each)
+local ok = helpers.ok
+local call = helpers.call
+local clear = helpers.clear
+
+describe('hostname()', function()
+  before_each(clear)
+
+  it('returns hostname string', function()
+    local actual = call('hostname')
+    ok(string.len(actual) > 1)
+    if call('executable', 'hostname') == 1 then
+      local expected = string.gsub(call('system', 'hostname'), '[\n\r]', '')
+      helpers.eq(expected, actual)
+    end
+  end)
+end)