Merge branch 'master' into expression-parser

46 files changed, 4739 insertions, 4679 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index ce554d351c..c6771fbc03 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -91,7 +91,8 @@ Dictionary nvim_get_hl_by_id(Integer hl_id, Boolean rgb, Error *err)
 {
   Dictionary dic = ARRAY_DICT_INIT;
   if (syn_get_final_id((int)hl_id) == 0) {
-    api_set_error(err, kErrorTypeException, "Invalid highlight id: %d", hl_id);
+    api_set_error(err, kErrorTypeException,
+                  "Invalid highlight id: %" PRId64, hl_id);
     return dic;
   }
   int attrcode = syn_id2attr((int)hl_id);
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index f874268910..766003a021 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -64,7 +64,6 @@
 #include "nvim/spell.h"
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
-#include "nvim/terminal.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/version.h"
@@ -1464,12 +1463,6 @@ void enter_buffer(buf_T *buf)
   /* mark cursor position as being invalid */
   curwin->w_valid = 0;
 
-  if (buf->terminal) {
-    terminal_resize(buf->terminal,
-                    (uint16_t)(MAX(0, curwin->w_width - win_col_off(curwin))),
-                    (uint16_t)curwin->w_height);
-  }
-
   /* Make sure the buffer is loaded. */
   if (curbuf->b_ml.ml_mfp == NULL) {    /* need to load the file */
     /* If there is no filetype, allow for detecting one.  Esp. useful for
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index c7cb51ac29..33bea8ef87 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -334,7 +334,7 @@ static struct vimvar {
   // VV_SEND_SERVER "servername"
   // VV_REG "register"
   // VV_OP "operator"
-  VV(VV_COUNT,          "count",            VAR_NUMBER, VV_COMPAT+VV_RO),
+  VV(VV_COUNT,          "count",            VAR_NUMBER, VV_RO),
   VV(VV_COUNT1,         "count1",           VAR_NUMBER, VV_RO),
   VV(VV_PREVCOUNT,      "prevcount",        VAR_NUMBER, VV_RO),
   VV(VV_ERRMSG,         "errmsg",           VAR_STRING, VV_COMPAT),
@@ -10672,6 +10672,10 @@ static void f_has(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       n = has_nvim_version(name + 5);
     } else if (STRICMP(name, "vim_starting") == 0) {
       n = (starting != 0);
+    } else if (STRICMP(name, "ttyin") == 0) {
+      n = stdin_isatty;
+    } else if (STRICMP(name, "ttyout") == 0) {
+      n = stdout_isatty;
     } else if (STRICMP(name, "multi_byte_encoding") == 0) {
       n = has_mbyte != 0;
 #if defined(USE_ICONV) && defined(DYNAMIC_ICONV)
@@ -22879,11 +22883,15 @@ void ex_checkhealth(exarg_T *eap)
     const char *vimruntime_env = os_getenv("VIMRUNTIME");
     if (vimruntime_env == NULL) {
       EMSG(_("E5009: $VIMRUNTIME is empty or unset"));
-      return;
     } else {
-      EMSG2(_("E5009: Invalid $VIMRUNTIME: %s"), os_getenv("VIMRUNTIME"));
-      return;
+      bool rtp_ok = NULL != strstr((char *)p_rtp, vimruntime_env);
+      if (rtp_ok) {
+        EMSG2(_("E5009: Invalid $VIMRUNTIME: %s"), vimruntime_env);
+      } else {
+        EMSG(_("E5009: Invalid 'runtimepath'"));
+      }
     }
+    return;
   }
 
   size_t bufsize = STRLEN(eap->arg) + sizeof("call health#check('')");
diff --git a/src/nvim/event/libuv_process.c b/src/nvim/event/libuv_process.c
index f6a567a520..758b35796e 100644
--- a/src/nvim/event/libuv_process.c
+++ b/src/nvim/event/libuv_process.c
@@ -38,7 +38,7 @@ int libuv_process_spawn(LibuvProcess *uvproc)
 #endif
   uvproc->uvopts.exit_cb = exit_cb;
   uvproc->uvopts.cwd = proc->cwd;
-  uvproc->uvopts.env = NULL;
+  uvproc->uvopts.env = NULL;  // Inherits the parent (nvim) env.
   uvproc->uvopts.stdio = uvproc->uvstdio;
   uvproc->uvopts.stdio_count = 3;
   uvproc->uvstdio[0].flags = UV_IGNORE;
diff --git a/src/nvim/event/process.c b/src/nvim/event/process.c
index 8371d3cd48..41e793500a 100644
--- a/src/nvim/event/process.c
+++ b/src/nvim/event/process.c
@@ -324,6 +324,13 @@ static void process_close(Process *proc)
   }
   assert(!proc->closed);
   proc->closed = true;
+
+  if (proc->detach) {
+    if (proc->type == kProcessTypeUv) {
+      uv_unref((uv_handle_t *)&(((LibuvProcess *)proc)->uv));
+    }
+  }
+
   switch (proc->type) {
     case kProcessTypeUv:
       libuv_process_close((LibuvProcess *)proc);
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 3bcea4b666..3202f8a848 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -3272,6 +3272,12 @@ const char * set_one_cmd_context(
   case CMD_echoerr:
   case CMD_call:
   case CMD_return:
+  case CMD_cexpr:
+  case CMD_caddexpr:
+  case CMD_cgetexpr:
+  case CMD_lexpr:
+  case CMD_laddexpr:
+  case CMD_lgetexpr:
     set_context_for_expression(xp, (char_u *)arg, ea.cmdidx);
     break;
 
@@ -9351,15 +9357,18 @@ put_view (
     }
   }
 
-  /*
-   * Local directory.
-   */
-  if (wp->w_localdir != NULL) {
+  //
+  // Local directory, if the current flag is not view options or the "curdir"
+  // option is included.
+  //
+  if (wp->w_localdir != NULL
+      && (flagp != &vop_flags || (*flagp & SSOP_CURDIR))) {
     if (fputs("lcd ", fd) < 0
         || ses_put_fname(fd, wp->w_localdir, flagp) == FAIL
-        || put_eol(fd) == FAIL)
+        || put_eol(fd) == FAIL) {
       return FAIL;
-    did_lcd = TRUE;
+    }
+    did_lcd = true;
   }
 
   return OK;
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index cabdda28cf..53f6ca0d2b 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -93,6 +93,13 @@ typedef struct {
   CmdlineColors colors;  ///< Last colors.
 } ColoredCmdline;
 
+/// Keeps track how much state must be sent to external ui.
+typedef enum {
+  kCmdRedrawNone,
+  kCmdRedrawPos,
+  kCmdRedrawAll,
+} CmdRedraw;
+
 /*
  * Variables shared between getcmdline(), redrawcmdline() and others.
  * These need to be saved when using CTRL-R |, that's why they are in a
@@ -122,6 +129,7 @@ struct cmdline_info {
   struct cmdline_info *prev_ccline;  ///< pointer to saved cmdline state
   char special_char;            ///< last putcmdline char (used for redraws)
   bool special_shift;           ///< shift of last putcmdline char
+  CmdRedraw redraw_state;       ///< needed redraw for external cmdline
 };
 /// Last value of prompt_id, incremented when doing new prompt
 static unsigned last_prompt_id = 0;
@@ -425,6 +433,7 @@ static uint8_t *command_line_enter(int firstc, long count, int indent)
     ccline.cmdbuff = NULL;
 
     if (ui_is_external(kUICmdline)) {
+      ccline.redraw_state = kCmdRedrawNone;
       ui_call_cmdline_hide(ccline.level);
     }
     ccline.level--;
@@ -1818,7 +1827,8 @@ static int command_line_changed(CommandLineState *s)
     // right-left typing.  Not efficient, but it works.
     // Do it only when there are no characters left to read
     // to avoid useless intermediate redraws.
-    if (vpeekc() == NUL) {
+    // if cmdline is external the ui handles shaping, no redraw needed.
+    if (!ui_is_external(kUICmdline) && vpeekc() == NUL) {
       redrawcmd();
     }
   }
@@ -2667,7 +2677,7 @@ static void draw_cmdline(int start, int len)
 
   if (ui_is_external(kUICmdline)) {
     ccline.special_char = NUL;
-    ui_ext_cmdline_show(&ccline);
+    ccline.redraw_state = kCmdRedrawAll;
     return;
   }
 
@@ -2879,7 +2889,7 @@ void cmdline_screen_cleared(void)
     if (prev_ccline->level == prev_level) {
       // don't redraw a cmdline already shown in the cmdline window
       if (prev_level != cmdwin_level) {
-        ui_ext_cmdline_show(prev_ccline);
+        prev_ccline->redraw_state = kCmdRedrawAll;
       }
       prev_level--;
     }
@@ -2887,6 +2897,28 @@ void cmdline_screen_cleared(void)
   }
 }
 
+/// called by ui_flush, do what redraws neccessary to keep cmdline updated.
+void cmdline_ui_flush(void)
+{
+  if (!ui_is_external(kUICmdline)) {
+    return;
+  }
+  int level = ccline.level;
+  CmdlineInfo *line = &ccline;
+  while (level > 0 && line) {
+    if (line->level == level) {
+      if (line->redraw_state == kCmdRedrawAll) {
+        ui_ext_cmdline_show(line);
+      } else if (line->redraw_state == kCmdRedrawPos) {
+        ui_call_cmdline_pos(line->cmdpos, line->level);
+      }
+      line->redraw_state = kCmdRedrawNone;
+      level--;
+    }
+    line = line->prev_ccline;
+  }
+}
+
 /*
  * Put a character on the command line.  Shifts the following text to the
  * right when "shift" is TRUE.  Used for CTRL-V, CTRL-K, etc.
@@ -2907,8 +2939,10 @@ void putcmdline(int c, int shift)
   } else {
     ccline.special_char = c;
     ccline.special_shift = shift;
-    ui_call_cmdline_special_char(cchar_to_string((char)(c)), shift,
-                                 ccline.level);
+    if (ccline.redraw_state != kCmdRedrawAll) {
+      ui_call_cmdline_special_char(cchar_to_string((char)(c)), shift,
+                                   ccline.level);
+    }
   }
   cursorcmd();
   ui_cursor_shape();
@@ -3249,7 +3283,7 @@ static void redrawcmdprompt(void)
   if (cmd_silent)
     return;
   if (ui_is_external(kUICmdline)) {
-    ui_ext_cmdline_show(&ccline);
+    ccline.redraw_state = kCmdRedrawAll;
     return;
   }
   if (ccline.cmdfirstc != NUL) {
@@ -3326,7 +3360,9 @@ static void cursorcmd(void)
     return;
 
   if (ui_is_external(kUICmdline)) {
-    ui_call_cmdline_pos(ccline.cmdpos, ccline.level);
+    if (ccline.redraw_state < kCmdRedrawPos) {
+      ccline.redraw_state = kCmdRedrawPos;
+    }
     return;
   }
 
@@ -4164,7 +4200,9 @@ addstar (
         || context == EXPAND_OWNSYNTAX
         || context == EXPAND_FILETYPE
         || context == EXPAND_PACKADD
-        || (context == EXPAND_TAGS && fname[0] == '/'))
+        || ((context == EXPAND_TAGS_LISTFILES
+             || context == EXPAND_TAGS)
+            && fname[0] == '/'))
       retval = vim_strnsave(fname, len);
     else {
       new_len = len + 2;                /* +2 for '^' at start, NUL at end */
@@ -5920,6 +5958,7 @@ static int ex_window(void)
   changed_line_abv_curs();
   invalidate_botline();
   if (ui_is_external(kUICmdline)) {
+    ccline.redraw_state = kCmdRedrawNone;
     ui_call_cmdline_hide(ccline.level);
   }
   redraw_later(SOME_VALID);
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index feb16f44d4..ae6c3f96e3 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -302,12 +302,9 @@ readfile (
   linenr_T skip_count = 0;
   linenr_T read_count = 0;
   int msg_save = msg_scroll;
-  linenr_T read_no_eol_lnum = 0;        /* non-zero lnum when last line of
-                                        * last read was missing the eol */
-  int try_mac = (vim_strchr(p_ffs, 'm') != NULL);
-  int try_dos = (vim_strchr(p_ffs, 'd') != NULL);
-  int try_unix = (vim_strchr(p_ffs, 'x') != NULL);
-  int file_rewind = FALSE;
+  linenr_T read_no_eol_lnum = 0;        // non-zero lnum when last line of
+                                        // last read was missing the eol
+  int file_rewind = false;
   int can_retry;
   linenr_T conv_error = 0;              /* line nr with conversion error */
   linenr_T illegal_byte = 0;            /* line nr with illegal byte */
@@ -639,37 +636,46 @@ readfile (
   curbuf->b_op_start.lnum = ((from == 0) ? 1 : from);
   curbuf->b_op_start.col = 0;
 
+  int try_mac = (vim_strchr(p_ffs, 'm') != NULL);
+  int try_dos = (vim_strchr(p_ffs, 'd') != NULL);
+  int try_unix = (vim_strchr(p_ffs, 'x') != NULL);
+
   if (!read_buffer) {
     int m = msg_scroll;
     int n = msg_scrolled;
 
-    /*
-     * The file must be closed again, the autocommands may want to change
-     * the file before reading it.
-     */
-    if (!read_stdin)
-      close(fd);                /* ignore errors */
+    // The file must be closed again, the autocommands may want to change
+    // the file before reading it.
+    if (!read_stdin) {
+      close(fd);                // ignore errors
+    }
 
-    /*
-     * The output from the autocommands should not overwrite anything and
-     * should not be overwritten: Set msg_scroll, restore its value if no
-     * output was done.
-     */
-    msg_scroll = TRUE;
-    if (filtering)
+    // The output from the autocommands should not overwrite anything and
+    // should not be overwritten: Set msg_scroll, restore its value if no
+    // output was done.
+    msg_scroll = true;
+    if (filtering) {
       apply_autocmds_exarg(EVENT_FILTERREADPRE, NULL, sfname,
-          FALSE, curbuf, eap);
-    else if (read_stdin)
+                           false, curbuf, eap);
+    } else if (read_stdin) {
       apply_autocmds_exarg(EVENT_STDINREADPRE, NULL, sfname,
-          FALSE, curbuf, eap);
-    else if (newfile)
+                           false, curbuf, eap);
+    } else if (newfile) {
       apply_autocmds_exarg(EVENT_BUFREADPRE, NULL, sfname,
-          FALSE, curbuf, eap);
-    else
+                           false, curbuf, eap);
+    } else {
       apply_autocmds_exarg(EVENT_FILEREADPRE, sfname, sfname,
-          FALSE, NULL, eap);
-    if (msg_scrolled == n)
+                           false, NULL, eap);
+    }
+
+    // autocommands may have changed it
+    try_mac = (vim_strchr(p_ffs, 'm') != NULL);
+    try_dos = (vim_strchr(p_ffs, 'd') != NULL);
+    try_unix = (vim_strchr(p_ffs, 'x') != NULL);
+
+    if (msg_scrolled == n) {
       msg_scroll = m;
+    }
 
     if (aborting()) {       /* autocmds may abort script processing */
       --no_wait_return;
@@ -1616,7 +1622,8 @@ rewind_retry:
             *ptr = NUL;                         /* end of line */
             len = (colnr_T)(ptr - line_start + 1);
             if (fileformat == EOL_DOS) {
-              if (ptr[-1] == CAR) {             /* remove CR */
+              if (ptr > line_start && ptr[-1] == CAR) {
+                // remove CR before NL
                 ptr[-1] = NUL;
                 len--;
               } else if (ff_error != EOL_DOS) {
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 2a041177d4..8874f0bb75 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -564,21 +564,22 @@ EXTERN int ru_col;              /* column for ruler */
 EXTERN int ru_wid;              /* 'rulerfmt' width of ruler when non-zero */
 EXTERN int sc_col;              /* column for shown command */
 
-/*
- * When starting or exiting some things are done differently (e.g. screen
- * updating).
- */
+//
+// When starting or exiting some things are done differently (e.g. screen
+// updating).
+//
+
+// First NO_SCREEN, then NO_BUFFERS, then 0 when startup finished.
 EXTERN int starting INIT(= NO_SCREEN);
-/* first NO_SCREEN, then NO_BUFFERS and then
- * set to 0 when starting up finished */
-EXTERN int exiting INIT(= FALSE);
-/* TRUE when planning to exit Vim.  Might
- * still keep on running if there is a changed
- * buffer. */
-// volatile because it is used in signal handler deathtrap().
+// true when planning to exit. Might keep running if there is a changed buffer.
+EXTERN int exiting INIT(= false);
+// is stdin a terminal?
+EXTERN int stdin_isatty INIT(= true);
+// is stdout a terminal?
+EXTERN int stdout_isatty INIT(= true);
+// true when doing full-screen output, otherwise only writing some messages.
+// volatile because it is used in a signal handler.
 EXTERN volatile int full_screen INIT(= false);
-// TRUE when doing full-screen output
-// otherwise only writing some messages
 
 EXTERN int restricted INIT(= FALSE);
 // TRUE when started in restricted mode (-Z)
diff --git a/src/nvim/main.c b/src/nvim/main.c
index ea7a58bda3..93afe11f3a 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1240,8 +1240,10 @@ static void init_startuptime(mparm_T *paramp)
 
 static void check_and_set_isatty(mparm_T *paramp)
 {
-  paramp->input_isatty = os_isatty(fileno(stdin));
-  paramp->output_isatty = os_isatty(fileno(stdout));
+  stdin_isatty
+    = paramp->input_isatty = os_isatty(fileno(stdin));
+  stdout_isatty
+    = paramp->output_isatty = os_isatty(fileno(stdout));
   paramp->err_isatty = os_isatty(fileno(stderr));
   TIME_MSG("window checked");
 }
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index a2fe90b3c2..1f62490ab9 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -539,7 +539,7 @@ static char *(p_ssop_values[]) = {"buffers", "winpos", "resize", "winsize",
                                   "localoptions", "options", "help", "blank",
                                   "globals", "slash", "unix",
                                   "sesdir", "curdir", "folds", "cursor",
-                                  "tabpages", NULL};
+                                  "tabpages", NULL };
 # endif
 # define SSOP_BUFFERS           0x001
 # define SSOP_WINPOS            0x002
@@ -557,16 +557,17 @@ static char *(p_ssop_values[]) = {"buffers", "winpos", "resize", "winsize",
 # define SSOP_FOLDS             0x2000
 # define SSOP_CURSOR            0x4000
 # define SSOP_TABPAGES          0x8000
-EXTERN char_u   *p_sh;          /* 'shell' */
-EXTERN char_u   *p_shcf;        /* 'shellcmdflag' */
-EXTERN char_u   *p_sp;          /* 'shellpipe' */
-EXTERN char_u   *p_shq;         /* 'shellquote' */
-EXTERN char_u   *p_sxq;         /* 'shellxquote' */
-EXTERN char_u   *p_sxe;         /* 'shellxescape' */
-EXTERN char_u   *p_srr;         /* 'shellredir' */
-EXTERN int p_stmp;              /* 'shelltemp' */
+
+EXTERN char_u   *p_sh;          // 'shell'
+EXTERN char_u   *p_shcf;        // 'shellcmdflag'
+EXTERN char_u   *p_sp;          // 'shellpipe'
+EXTERN char_u   *p_shq;         // 'shellquote'
+EXTERN char_u   *p_sxq;         // 'shellxquote'
+EXTERN char_u   *p_sxe;         // 'shellxescape'
+EXTERN char_u   *p_srr;         // 'shellredir'
+EXTERN int p_stmp;              // 'shelltemp'
 #ifdef BACKSLASH_IN_FILENAME
-EXTERN int p_ssl;               /* 'shellslash' */
+EXTERN int p_ssl;               // 'shellslash'
 #endif
 EXTERN char_u   *p_stl;         // 'statusline'
 EXTERN int p_sr;                // 'shiftround'
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 7cecb16686..52e478e78a 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -1924,7 +1924,7 @@ return {
       vi_def=true,
       varname='p_scbk',
       redraw={'current_buffer'},
-      defaults={if_true={vi=1000}}
+      defaults={if_true={vi=10000}}
     },
     {
       full_name='scrollbind', abbreviation='scb',
@@ -2610,7 +2610,7 @@ return {
       deny_duplicates=true,
       vi_def=true,
       varname='p_vop',
-      defaults={if_true={vi="folds,options,cursor"}}
+      defaults={if_true={vi="folds,options,cursor,curdir"}}
     },
     {
       full_name='viminfo', abbreviation='vi',
diff --git a/src/nvim/os/fs.c b/src/nvim/os/fs.c
index 78627f8703..aa28b95c30 100644
--- a/src/nvim/os/fs.c
+++ b/src/nvim/os/fs.c
@@ -133,22 +133,12 @@ bool os_isdir(const char_u *name)
 int os_nodetype(const char *name)
   FUNC_ATTR_NONNULL_ALL
 {
-#ifdef WIN32
-  // Edge case from Vim os_win32.c:
-  // We can't open a file with a name "\\.\con" or "\\.\prn", trying to read
-  // from it later will cause Vim to hang. Thus return NODE_WRITABLE here.
-  if (STRNCMP(name, "\\\\.\\", 4) == 0) {
-    return NODE_WRITABLE;
-  }
-#endif
-
+#ifndef WIN32  // Unix
   uv_stat_t statbuf;
   if (0 != os_stat(name, &statbuf)) {
     return NODE_NORMAL;  // File doesn't exist.
   }
-
-#ifndef WIN32
-  // libuv does not handle BLK and DIR in uv_handle_type.
+  // uv_handle_type does not distinguish BLK and DIR.
   //    Related: https://github.com/joyent/libuv/pull/1421
   if (S_ISREG(statbuf.st_mode) || S_ISDIR(statbuf.st_mode)) {
     return NODE_NORMAL;
@@ -156,48 +146,51 @@ int os_nodetype(const char *name)
   if (S_ISBLK(statbuf.st_mode)) {  // block device isn't writable
     return NODE_OTHER;
   }
-#endif
+  // Everything else is writable?
+  // buf_write() expects NODE_WRITABLE for char device /dev/stderr.
+  return NODE_WRITABLE;
+#else  // Windows
+  // Edge case from Vim os_win32.c:
+  // We can't open a file with a name "\\.\con" or "\\.\prn", trying to read
+  // from it later will cause Vim to hang. Thus return NODE_WRITABLE here.
+  if (STRNCMP(name, "\\\\.\\", 4) == 0) {
+    return NODE_WRITABLE;
+  }
 
-  // Vim os_win32.c:mch_nodetype does this (since patch 7.4.015):
-  //    if (enc_codepage >= 0 && (int)GetACP() != enc_codepage) {
-  //      wn = enc_to_utf16(name, NULL);
-  //      hFile = CreatFile(wn, ...)
-  // to get a HANDLE. But libuv just calls win32's _get_osfhandle() on the fd we
-  // give it. uv_fs_open calls fs__capture_path which does a similar dance and
-  // saves us the hassle.
+  // Vim os_win32.c:mch_nodetype does (since 7.4.015):
+  //    wn = enc_to_utf16(name, NULL);
+  //    hFile = CreatFile(wn, ...)
+  // to get a HANDLE. Whereas libuv just calls _get_osfhandle() on the fd we
+  // give it. But uv_fs_open later calls fs__capture_path which does a similar
+  // utf8-to-utf16 dance and saves us the hassle.
 
-  int nodetype = NODE_WRITABLE;
+  // macOS: os_open(/dev/stderr) would return UV_EACCES.
   int fd = os_open(name, O_RDONLY
-#ifdef O_NONBLOCK
+# ifdef O_NONBLOCK
                    | O_NONBLOCK
-#endif
+# endif
                    , 0);
-  if (fd == -1) {
-    return NODE_OTHER;  // open() failed.
+  if (fd < 0) {  // open() failed.
+    return NODE_NORMAL;
+  }
+  int guess = uv_guess_handle(fd);
+  if (close(fd) == -1) {
+    ELOG("close(%d) failed. name='%s'", fd, name);
   }
 
-  switch (uv_guess_handle(fd)) {
-    case UV_TTY:         // FILE_TYPE_CHAR
-      nodetype = NODE_WRITABLE;
-      break;
-    case UV_FILE:        // FILE_TYPE_DISK
-      nodetype = NODE_NORMAL;
-      break;
-    case UV_NAMED_PIPE:  // not handled explicitly in Vim os_win32.c
-    case UV_UDP:         // unix only
-    case UV_TCP:         // unix only
+  switch (guess) {
+    case UV_TTY:          // FILE_TYPE_CHAR
+      return NODE_WRITABLE;
+    case UV_FILE:         // FILE_TYPE_DISK
+      return NODE_NORMAL;
+    case UV_NAMED_PIPE:   // not handled explicitly in Vim os_win32.c
+    case UV_UDP:          // unix only
+    case UV_TCP:          // unix only
     case UV_UNKNOWN_HANDLE:
     default:
-#ifdef WIN32
-      nodetype = NODE_NORMAL;
-#else
-      nodetype = NODE_WRITABLE;  // Everything else is writable?
-#endif
-      break;
+      return NODE_OTHER;  // Vim os_win32.c default
   }
-
-  close(fd);
-  return nodetype;
+#endif
 }
 
 /// Gets the absolute path of the currently running executable.
@@ -394,9 +387,11 @@ end:
 /// @param mode Permissions for the newly-created file (IGNORED if 'flags' is
 ///        not `O_CREAT` or `O_TMPFILE`), subject to the current umask
 /// @return file descriptor, or libuv error code on failure
-int os_open(const char* path, int flags, int mode)
-  FUNC_ATTR_NONNULL_ALL
+int os_open(const char *path, int flags, int mode)
 {
+  if (path == NULL) {  // uv_fs_open asserts on NULL. #7561
+    return UV_EINVAL;
+  }
   int r;
   RUN_UV_FS_FUNC(r, uv_fs_open, path, flags, mode, NULL);
   return r;
@@ -603,12 +598,12 @@ int os_fsync(int fd)
 
 /// Get stat information for a file.
 ///
-/// @return libuv return code.
+/// @return libuv return code, or -errno
 static int os_stat(const char *name, uv_stat_t *statbuf)
   FUNC_ATTR_NONNULL_ARG(2)
 {