Merge #6427 from ZyX-I/writefile-allow-omitting-fsync

eval: Make writefile() able to disable fsync()

ci/common/suite.sh

@@ -69,6 +69,7 @@ run_test_wd() {
   while test $restarts -gt 0 ; do
     : > "${status_file}"
     (
+      FAILED=0
       if ! (
         set -o pipefail
         eval "$cmd" 2>&1 | tee -a "$output_file"

runtime/doc/eval.txt

@@ -7915,6 +7915,12 @@ writefile({list}, {fname} [, {flags}])
 		appended to the file: >
 			:call writefile(["foo"], "event.log", "a")
 			:call writefile(["bar"], "event.log", "a")
+<
+		When {flags} contains "S" fsync() call is not used, with "s" 
+		it is used, 'fsync' option applies by default. No fsync() 
+		means that writefile() will finish faster, but writes may be 
+		left in OS buffers and not yet written to disk. Such changes 
+		will disappear if system crashes before OS does writing.
 
 		All NL characters are replaced with a NUL character.
 		Inserting CR characters needs to be done before passing {list}

runtime/doc/options.txt

@@ -2740,6 +2740,9 @@ A jump table for the options with a short description can be found at |Q_op|.
 	mode, so it may be undesirable in some situations.  Be warned that
 	turning this off increases the chances of data loss after a crash.
 
+	Currently applies only to writing the buffer with e.g. |:w| and 
+	|writefile()|.
+
 				   *'gdefault'* *'gd'* *'nogdefault'* *'nogd'*
 'gdefault' 'gd'		boolean	(default off)
 			global

src/nvim/buffer.c

@@ -2724,7 +2724,7 @@ fileinfo (
     else
       name = curbuf->b_ffname;
     home_replace(shorthelp ? curbuf : NULL, name, p,
-        (int)(IOSIZE - (p - buffer)), TRUE);
+                 (size_t)(IOSIZE - (p - buffer)), true);
   }
 
   vim_snprintf_add((char *)buffer, IOSIZE, "\"%s%s%s%s%s%s",
@@ -2889,7 +2889,7 @@ void maketitle(void)
         buf[off++] = ' ';
         buf[off++] = '(';
         home_replace(curbuf, curbuf->b_ffname,
-            buf + off, SPACE_FOR_DIR - off, TRUE);
+                     buf + off, (size_t)(SPACE_FOR_DIR - off), true);
 #ifdef BACKSLASH_IN_FILENAME
         /* avoid "c:/name" to be reduced to "c" */
         if (isalpha(buf[off]) && buf[off + 1] == ':')

src/nvim/eval.c

@@ -17421,16 +17421,24 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   bool binary = false;
   bool append = false;
+  bool do_fsync = !!p_fs;
   if (argvars[2].v_type != VAR_UNKNOWN) {
     const char *const flags = tv_get_string_chk(&argvars[2]);
     if (flags == NULL) {
       return;
     }
-    if (strchr(flags, 'b')) {
+    for (const char *p = flags; *p; p++) {
-      binary = true;
+      switch (*p) {
-    }
+        case 'b': { binary = true; break; }
-    if (strchr(flags, 'a')) {
+        case 'a': { append = true; break; }
-      append = true;
+        case 's': { do_fsync = true; break; }
+        case 'S': { do_fsync = false; break; }
+        default: {
+          // Using %s, p and not %c, *p to preserve multibyte characters
+          emsgf(_("E5060: Unknown flag: %s"), p);
+          return;
+        }
+      }
     }
   }
 
@@ -17453,7 +17461,7 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     if (write_list(&fp, argvars[0].vval.v_list, binary)) {
       rettv->vval.v_number = 0;
     }
-    if ((error = file_close(&fp)) != 0) {
+    if ((error = file_close(&fp, do_fsync)) != 0) {
       emsgf(_("E80: Error when closing file %s: %s"),
             fname, os_strerror(error));
     }

src/nvim/fileio.c

@@ -200,18 +200,14 @@ void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
 {
   int msg_scroll_save;
 
-  if (msg_silent != 0)
+  if (msg_silent != 0) {
     return;
-  msg_add_fname(buf, name);         /* put file name in IObuff with quotes */
+  }
-  /* If it's extremely long, truncate it. */
+  add_quoted_fname((char *)IObuff, IOSIZE - 80, buf, (const char *)name);
-  if (STRLEN(IObuff) > IOSIZE - 80)
+  xstrlcat((char *)IObuff, (const char *)s, IOSIZE);
-    IObuff[IOSIZE - 80] = NUL;
+  // For the first message may have to start a new line.
-  STRCAT(IObuff, s);
+  // For further ones overwrite the previous one, reset msg_scroll before
-  /*
+  // calling filemess().
-   * For the first message may have to start a new line.
-   * For further ones overwrite the previous one, reset msg_scroll before
-   * calling filemess().
-   */
   msg_scroll_save = msg_scroll;
   if (shortmess(SHM_OVERALL) && !exiting && p_verbose == 0)
     msg_scroll = FALSE;
@@ -1800,8 +1796,8 @@ failed:
     }
 
     if (!filtering && !(flags & READ_DUMMY)) {
-      msg_add_fname(curbuf, sfname);         /* fname in IObuff with quotes */
+      add_quoted_fname((char *)IObuff, IOSIZE, curbuf, (const char *)sfname);
-      c = FALSE;
+      c = false;
 
 #ifdef UNIX
 # ifdef S_ISFIFO
@@ -2258,9 +2254,16 @@ buf_write (
   int len;
   linenr_T lnum;
   long nchars;
-  char_u          *errmsg = NULL;
+#define SET_ERRMSG_NUM(num, msg) \
-  int errmsg_allocated = FALSE;
+  errnum = num, errmsg = msg, errmsgarg = 0
-  char_u          *errnum = NULL;
+#define SET_ERRMSG_ARG(msg, error) \
+  errnum = NULL, errmsg = msg, errmsgarg = error
+#define SET_ERRMSG(msg) \
+  errnum = NULL, errmsg = msg, errmsgarg = 0
+  const char *errnum = NULL;
+  char *errmsg = NULL;
+  int errmsgarg = 0;
+  bool errmsg_allocated = false;
   char_u          *buffer;
   char_u smallbuf[SMBUFSIZE];
   char_u          *backup_ext;
@@ -2282,7 +2285,6 @@ buf_write (
   /* writing everything */
   int whole = (start == 1 && end == buf->b_ml.ml_line_count);
   linenr_T old_line_count = buf->b_ml.ml_line_count;
-  int attr;
   int fileformat;
   int write_bin;
   struct bw_info write_info;            /* info for buf_write_bytes() */
@@ -2577,13 +2579,11 @@ buf_write (
     perm = file_info_old.stat.st_mode;
     if (!S_ISREG(file_info_old.stat.st_mode)) {             /* not a file */
       if (S_ISDIR(file_info_old.stat.st_mode)) {
-        errnum = (char_u *)"E502: ";
+        SET_ERRMSG_NUM("E502", _("is a directory"));
-        errmsg = (char_u *)_("is a directory");
         goto fail;
       }
       if (os_nodetype((char *)fname) != NODE_WRITABLE) {
-        errnum = (char_u *)"E503: ";
+        SET_ERRMSG_NUM("E503", _("is not a file or writable device"));
-        errmsg = (char_u *)_("is not a file or writable device");
         goto fail;
       }
       /* It's a device of some kind (or a fifo) which we can write to
@@ -2599,8 +2599,7 @@ buf_write (
        */
   c = os_nodetype((char *)fname);
   if (c == NODE_OTHER) {
-    errnum = (char_u *)"E503: ";
+    SET_ERRMSG_NUM("E503", _("is not a file or writable device"));
-    errmsg = (char_u *)_("is not a file or writable device");
     goto fail;
   }
   if (c == NODE_WRITABLE) {
@@ -2612,8 +2611,7 @@ buf_write (
     if (perm < 0) {
       newfile = true;
     } else if (os_isdir(fname)) {
-      errnum = (char_u *)"E502: ";
+      SET_ERRMSG_NUM("E502", _("is a directory"));
-      errmsg = (char_u *)_("is a directory");
       goto fail;
     }
     if (overwriting) {
@@ -2632,11 +2630,9 @@ buf_write (
 
     if (!forceit && file_readonly) {
       if (vim_strchr(p_cpo, CPO_FWRITE) != NULL) {
-        errnum = (char_u *)"E504: ";
+        SET_ERRMSG_NUM("E504", _(err_readonly));
-        errmsg = (char_u *)_(err_readonly);
       } else {
-        errnum = (char_u *)"E505: ";
+        SET_ERRMSG_NUM("E505", _("is read-only (add ! to override)"));
-        errmsg = (char_u *)_("is read-only (add ! to override)");
       }
       goto fail;
     }
@@ -2904,23 +2900,27 @@ buf_write (
             while ((write_info.bw_len = read_eintr(fd, copybuf,
                         BUFSIZE)) > 0) {
               if (buf_write_bytes(&write_info) == FAIL) {
-                errmsg = (char_u *)_(
+                SET_ERRMSG(_(
-                    "E506: Can't write to backup file (add ! to override)");
+                    "E506: Can't write to backup file (add ! to override)"));
                 break;
               }
               os_breakcheck();
               if (got_int) {
-                errmsg = (char_u *)_(e_interr);
+                SET_ERRMSG(_(e_interr));
                 break;
               }
             }
 
-            if (close(bfd) < 0 && errmsg == NULL)
+            int error;
-              errmsg = (char_u *)_(
+            if ((error = os_close(bfd)) != 0 && errmsg == NULL) {
-                  "E507: Close error for backup file (add ! to override)");
+              SET_ERRMSG_ARG(_("E507: Close error for backup file "
-            if (write_info.bw_len < 0)
+                               "(add ! to override): %s"),
-              errmsg = (char_u *)_(
+                             error);
-                  "E508: Can't read file for backup (add ! to override)");
+            }
+            if (write_info.bw_len < 0) {
+              SET_ERRMSG(_(
+                  "E508: Can't read file for backup (add ! to override)"));
+            }
 #ifdef UNIX
             set_file_time(backup,
                           file_info_old.stat.st_atim.tv_sec,
@@ -2937,18 +2937,19 @@ buf_write (
         }
       }
 nobackup:
-      close(fd);                /* ignore errors for closing read file */
+      os_close(fd);  // Ignore errors for closing read file.
       xfree(copybuf);
 
-      if (backup == NULL && errmsg == NULL)
+      if (backup == NULL && errmsg == NULL) {
-        errmsg = (char_u *)_(
+        SET_ERRMSG(_(
-            "E509: Cannot create backup file (add ! to override)");
+            "E509: Cannot create backup file (add ! to override)"));
-      /* ignore errors when forceit is TRUE */
+      }
+      // Ignore errors when forceit is TRUE.
       if ((some_error || errmsg != NULL) && !forceit) {
         retval = FAIL;
         goto fail;
       }
-      errmsg = NULL;
+      SET_ERRMSG(NULL);
     } else {
       char_u      *dirp;
       char_u      *p;
@@ -2963,8 +2964,7 @@ nobackup:
        * anyway, thus we need an extra check here.
        */
       if (file_readonly && vim_strchr(p_cpo, CPO_FWRITE) != NULL) {
-        errnum = (char_u *)"E504: ";
+        SET_ERRMSG_NUM("E504", _(err_readonly));
-        errmsg = (char_u *)_(err_readonly);
         goto fail;
       }
 
@@ -3028,7 +3028,7 @@ nobackup:
         }
       }
       if (backup == NULL && !forceit) {
-        errmsg = (char_u *)_("E510: Can't make backup file (add ! to override)");
+        SET_ERRMSG(_("E510: Can't make backup file (add ! to override)"));
         goto fail;
       }
     }
@@ -3069,7 +3069,7 @@ nobackup:
       && !(exiting && backup != NULL)) {
     ml_preserve(buf, FALSE);
     if (got_int) {
-      errmsg = (char_u *)_(e_interr);
+      SET_ERRMSG(_(e_interr));
       goto restore_backup;
     }
   }
@@ -3140,8 +3140,8 @@ nobackup:
      */
     if (*p_ccv != NUL) {
       wfname = vim_tempname();
-      if (wfname == NULL) {             /* Can't write without a tempfile! */
+      if (wfname == NULL) {  // Can't write without a tempfile!
-        errmsg = (char_u *)_("E214: Can't find temp file for writing");
+        SET_ERRMSG(_("E214: Can't find temp file for writing"));
         goto restore_backup;
       }
     }
@@ -3153,8 +3153,8 @@ nobackup:
       && wfname == fname
       ) {
     if (!forceit) {
-      errmsg = (char_u *)_(
+      SET_ERRMSG(_(
-          "E213: Cannot convert (add ! to write without conversion)");
+          "E213: Cannot convert (add ! to write without conversion)"));
       goto restore_backup;
     }
     notconverted = TRUE;
@@ -3189,11 +3189,10 @@ nobackup:
       if ((!newfile && os_fileinfo_hardlinks(&file_info) > 1)
           || (os_fileinfo_link((char *)fname, &file_info)
               && !os_fileinfo_id_equal(&file_info, &file_info_old))) {
-        errmsg = (char_u *)_("E166: Can't open linked file for writing");
+        SET_ERRMSG(_("E166: Can't open linked file for writing"));
-      } else
+      } else {
 #endif
-      {
+        SET_ERRMSG_ARG(_("E212: Can't open file for writing: %s"), fd);
-        errmsg = (char_u *)_("E212: Can't open file for writing");
         if (forceit && vim_strchr(p_cpo, CPO_FWRITE) == NULL
             && perm >= 0) {
 #ifdef UNIX
@@ -3211,7 +3210,9 @@ nobackup:
             os_remove((char *)wfname);
           continue;
         }
+#ifdef UNIX
       }
+#endif
     }
 
 restore_backup:
@@ -3253,7 +3254,7 @@ restore_backup:
       xfree(wfname);
     goto fail;
   }
-  errmsg = NULL;
+  SET_ERRMSG(NULL);
 
 
   write_info.bw_fd = fd;
@@ -3373,7 +3374,6 @@ restore_backup:
     nchars += len;
   }
 
-#if defined(UNIX)
   // On many journalling file systems there is a bug that causes both the
   // original and the backup file to be lost when halting the system right
   // after writing the file.  That's because only the meta-data is
@@ -3382,11 +3382,11 @@ restore_backup:
   // For a device do try the fsync() but don't complain if it does not work
   // (could be a pipe).
   // If the 'fsync' option is FALSE, don't fsync().  Useful for laptops.
-  if (p_fs && os_fsync(fd) != 0 && !device) {
+  int error;
-    errmsg = (char_u *)_("E667: Fsync failed");
+  if (p_fs && (error = os_fsync(fd)) != 0 && !device) {
+    SET_ERRMSG_ARG(_("E667: Fsync failed: %s"), error);
     end = 0;
   }
-#endif
 
 #ifdef HAVE_SELINUX
   /* Probably need to set the security context. */
@@ -3416,8 +3416,8 @@ restore_backup:
   }
 #endif
 
-  if (close(fd) != 0) {
+  if ((error = os_close(fd)) != 0) {
-    errmsg = (char_u *)_("E512: Close failed");
+    SET_ERRMSG_ARG(_("E512: Close failed: %s"), error);
     end = 0;
   }
 
@@ -3454,21 +3454,24 @@ restore_backup:
   if (end == 0) {
     if (errmsg == NULL) {
       if (write_info.bw_conv_error) {
-        if (write_info.bw_conv_error_lnum == 0)
+        if (write_info.bw_conv_error_lnum == 0) {
-          errmsg = (char_u *)_(
+          SET_ERRMSG(_(
-              "E513: write error, conversion failed (make 'fenc' empty to override)");
+              "E513: write error, conversion failed "
-        else {
+              "(make 'fenc' empty to override)"));
-          errmsg_allocated = TRUE;
+        } else {
-          errmsg = xmalloc(300);
+          errmsg_allocated = true;
-          vim_snprintf((char *)errmsg, 300,
+          SET_ERRMSG(xmalloc(300));
-              _("E513: write error, conversion failed in line %" PRId64
+          vim_snprintf(
+              errmsg, 300,
+              _("E513: write error, conversion failed in line %" PRIdLINENR
                 " (make 'fenc' empty to override)"),
-              (int64_t)write_info.bw_conv_error_lnum);
+              write_info.bw_conv_error_lnum);
         }
-      } else if (got_int)
+      } else if (got_int) {
-        errmsg = (char_u *)_(e_interr);
+        SET_ERRMSG(_(e_interr));
-      else
+      } else {
-        errmsg = (char_u *)_("E514: write error (file system full?)");
+        SET_ERRMSG(_("E514: write error (file system full?)"));
+      }
     }
 
     /*
@@ -3523,8 +3526,8 @@ restore_backup:
   fname = sfname;           /* use shortname now, for the messages */
 #endif
   if (!filtering) {
-    msg_add_fname(buf, fname);          /* put fname in IObuff with quotes */
+    add_quoted_fname((char *)IObuff, IOSIZE, buf, (const char *)fname);
-    c = FALSE;
+    c = false;
     if (write_info.bw_conv_error) {
       STRCAT(IObuff, _(" CONVERSION ERROR"));
       c = TRUE;
@@ -3673,33 +3676,32 @@ nofail:
 #endif
 
   if (errmsg != NULL) {
-    int numlen = errnum != NULL ? (int)STRLEN(errnum) : 0;
+    // - 100 to save some space for further error message
-
-    attr = hl_attr(HLF_E);      /* set highlight for error messages */
-    msg_add_fname(buf,
 #ifndef UNIX
-        sfname
+    add_quoted_fname((char *)IObuff, IOSIZE - 100, buf, (const char *)sfname);
 #else
-        fname
+    add_quoted_fname((char *)IObuff, IOSIZE - 100, buf, (const char *)fname);
 #endif
-        );                      /* put file name in IObuff with quotes */
-    if (STRLEN(IObuff) + STRLEN(errmsg) + numlen >= IOSIZE)
-      IObuff[IOSIZE - STRLEN(errmsg) - numlen - 1] = NUL;
-    /* If the error message has the form "is ...", put the error number in
-     * front of the file name. */
     if (errnum != NULL) {
-      STRMOVE(IObuff + numlen, IObuff);
+      if (errmsgarg != 0) {
-      memmove(IObuff, errnum, (size_t)numlen);
+        emsgf("%s: %s%s: %s", errnum, IObuff, errmsg, os_strerror(errmsgarg));
+      } else {
+        emsgf("%s: %s%s", errnum, IObuff, errmsg);
+      }
+    } else if (errmsgarg != 0) {
+      emsgf(errmsg, os_strerror(errmsgarg));
+    } else {
+      emsgf(errmsg);
     }
-    STRCAT(IObuff, errmsg);
+    if (errmsg_allocated) {
-    emsg(IObuff);
-    if (errmsg_allocated)
       xfree(errmsg);
+    }
 
     retval = FAIL;
     if (end == 0) {
+      const int attr = hl_attr(HLF_E);  // Set highlight for error messages.
       MSG_PUTS_ATTR(_("\nWARNING: Original file may be lost or damaged\n"),
-          attr | MSG_HIST);
+                    attr | MSG_HIST);
       MSG_PUTS_ATTR(_(
               "don't quit the editor until the file is successfully written!"),
           attr | MSG_HIST);
@@ -3759,6 +3761,9 @@ nofail:
   got_int |= prev_got_int;
 
   return retval;
+#undef SET_ERRMSG
+#undef SET_ERRMSG_ARG
+#undef SET_ERRMSG_NUM
 }
 
 /*
@@ -3802,16 +3807,25 @@ static int set_rw_fname(char_u *fname, char_u *sfname)
   return OK;
 }
 
-/*
+/// Put file name into the specified buffer with quotes
- * Put file name into IObuff with quotes.
+///
- */
+/// Replaces home directory at the start with `~`.
-void msg_add_fname(buf_T *buf, char_u *fname)
+///
+/// @param[out]  ret_buf  Buffer to save results to.
+/// @param[in]  buf_len  ret_buf length.
+/// @param[in]  buf  buf_T file name is coming from.
+/// @param[in]  fname  File name to write.
+static void add_quoted_fname(char *const ret_buf, const size_t buf_len,
+                             const buf_T *const buf, const char *fname)
+  FUNC_ATTR_NONNULL_ARG(1)
 {
-  if (fname == NULL)
+  if (fname == NULL) {
-    fname = (char_u *)"-stdin-";
+    fname = "-stdin-";
-  home_replace(buf, fname, IObuff + 1, IOSIZE - 4, TRUE);
+  }
-  IObuff[0] = '"';
+  ret_buf[0] = '"';
-  STRCAT(IObuff, "\" ");
+  home_replace(buf, (const char_u *)fname, (char_u *)ret_buf + 1,
+               (int)buf_len - 4, true);
+  xstrlcat(ret_buf, "\" ", buf_len);
 }
 
 /// Append message for text mode to IObuff.

src/nvim/message.c

@@ -573,16 +573,17 @@ void emsg_invreg(int name)
 /// Print an error message with unknown number of arguments
 bool emsgf(const char *const fmt, ...)
 {
+  static char errbuf[IOSIZE];
   if (emsg_not_now()) {
     return true;
   }
 
   va_list ap;
   va_start(ap, fmt);
-  vim_vsnprintf((char *) IObuff, IOSIZE, fmt, ap, NULL);
+  vim_vsnprintf(errbuf, sizeof(errbuf), fmt, ap, NULL);
   va_end(ap);
 
-  return emsg(IObuff);
+  return emsg((const char_u *)errbuf);
 }
 
 static void msg_emsgf_event(void **argv)

src/nvim/os/env.c

@@ -703,7 +703,8 @@ char *vim_getenv(const char *name)
 /// @param dstlen Maximum length of the result
 /// @param one If true, only replace one file name, including spaces and commas
 ///            in the file name
-void home_replace(buf_T *buf, char_u *src, char_u *dst, int dstlen, bool one)
+void home_replace(const buf_T *const buf, const char_u *src,
+                  char_u *dst, size_t dstlen, bool one)
 {
   size_t dirlen = 0, envlen = 0;
   size_t len;
@@ -717,7 +718,7 @@ void home_replace(buf_T *buf, char_u *src, char_u *dst, int dstlen, bool one)
    * If the file is a help file, remove the path completely.
    */
   if (buf != NULL && buf->b_help) {
-    STRCPY(dst, path_tail(src));
+    xstrlcpy((char *)dst, (char *)path_tail(src), dstlen);
     return;
   }
 
@@ -809,7 +810,7 @@ char_u * home_replace_save(buf_T *buf, char_u *src) FUNC_ATTR_NONNULL_RET
     len += STRLEN(src);
   }
   char_u *dst = xmalloc(len);
-  home_replace(buf, src, dst, (int)len, true);
+  home_replace(buf, src, dst, len, true);
   return dst;
 }
 

src/nvim/os/fileio.c

@@ -113,27 +113,31 @@ FileDescriptor *file_open_new(int *const error, const char *const fname,
 /// Close file and free its buffer
 ///
 /// @param[in,out]  fp  File to close.
+/// @param[in]  do_fsync  If true, use fsync() to write changes to disk.
 ///
 /// @return 0 or error code.
-int file_close(FileDescriptor *const fp) FUNC_ATTR_NONNULL_ALL
+int file_close(FileDescriptor *const fp, const bool do_fsync)
+  FUNC_ATTR_NONNULL_ALL
 {
-  const int error = file_fsync(fp);
+  const int flush_error = (do_fsync ? file_fsync(fp) : file_flush(fp));
-  const int error2 = os_close(fp->fd);
+  const int close_error = os_close(fp->fd);
   rbuffer_free(fp->rv);
-  if (error2 != 0) {
+  if (close_error != 0) {
-    return error2;
+    return close_error;
   }
-  return error;
+  return flush_error;
 }
 
 /// Close and free file obtained using file_open_new()
 ///
 /// @param[in,out]  fp  File to close.
+/// @param[in]  do_fsync  If true, use fsync() to write changes to disk.
 ///
 /// @return 0 or error code.
-int file_free(FileDescriptor *const fp) FUNC_ATTR_NONNULL_ALL
+int file_free(FileDescriptor *const fp, const bool do_fsync)
+  FUNC_ATTR_NONNULL_ALL
 {
-  const int ret = file_close(fp);
+  const int ret = file_close(fp, do_fsync);
   xfree(fp);
   return ret;
 }

src/nvim/path.c

@@ -84,15 +84,15 @@ FileComparison path_full_compare(char_u *s1, char_u *s2, int checkname)
 ///
 /// @return pointer just past the last path separator (empty string, if fname
 ///         ends in a slash), or empty string if fname is NULL.
-char_u *path_tail(char_u *fname)
+char_u *path_tail(const char_u *fname)
   FUNC_ATTR_NONNULL_RET
 {
   if (fname == NULL) {
     return (char_u *)"";
   }
 
-  char_u *tail = get_past_head(fname);
+  const char_u *tail = get_past_head(fname);
-  char_u *p = tail;
+  const char_u *p = tail;
   // Find last part of path.
   while (*p != NUL) {
     if (vim_ispathsep_nocolon(*p)) {
@@ -100,7 +100,7 @@ char_u *path_tail(char_u *fname)
     }
     mb_ptr_adv(p);
   }
-  return tail;
+  return (char_u *)tail;
 }
 
 /// Get pointer to tail of "fname", including path separators.
@@ -174,9 +174,9 @@ const char *path_next_component(const char *fname)
 /// Get a pointer to one character past the head of a path name.
 /// Unix: after "/"; Win: after "c:\"
 /// If there is no head, path is returned.
-char_u *get_past_head(char_u *path)
+char_u *get_past_head(const char_u *path)
 {
-  char_u *retval = path;
+  const char_u *retval = path;
 
 #ifdef WIN32
   // May skip "c:"
@@ -189,7 +189,7 @@ char_u *get_past_head(char_u *path)
     ++retval;
   }
 
-  return retval;
+  return (char_u *)retval;
 }
 
 /*

src/nvim/shada.c

@@ -811,7 +811,7 @@ static int open_shada_file_for_reading(const char *const fname,
 /// Wrapper for closing file descriptors
 static void close_file(void *cookie)
 {
-  const int error = file_free(cookie);
+  const int error = file_free(cookie, true);
   if (error != 0) {
     emsgf(_(SERR "System error while closing ShaDa file: %s"),
           os_strerror(error));

test/functional/eval/writefile_spec.lua

@@ -80,6 +80,13 @@ describe('writefile()', function()
     eq('a\0\0\0b', read_file(fname))
   end)
 
+  it('writes with s and S', function()
+    eq(0, funcs.writefile({'\na\nb\n'}, fname, 'bs'))
+    eq('\0a\0b\0', read_file(fname))
+    eq(0, funcs.writefile({'a\n\n\nb'}, fname, 'bS'))
+    eq('a\0\0\0b', read_file(fname))
+  end)
+
   it('correctly overwrites file', function()
     eq(0, funcs.writefile({'\na\nb\n'}, fname, 'b'))
     eq('\0a\0b\0', read_file(fname))
@@ -115,6 +122,8 @@ describe('writefile()', function()
       eq('\nE729: using Funcref as a String',
          redir_exec(('call writefile(%s)'):format(args:format('function("tr")'))))
     end
+    eq('\nE5060: Unknown flag: «»',
+       redir_exec(('call writefile([], "%s", "bs«»")'):format(fname)))
     eq('TEST', read_file(fname))
   end)
 

test/functional/ex_cmds/write_spec.lua

@@ -1,15 +1,28 @@
 local helpers = require('test.functional.helpers')(after_each)
+local lfs = require('lfs')
 local eq, eval, clear, write_file, execute, source, insert =
   helpers.eq, helpers.eval, helpers.clear, helpers.write_file,
   helpers.execute, helpers.source, helpers.insert
+local redir_exec = helpers.redir_exec
+local exc_exec = helpers.exc_exec
+local command = helpers.command
+local funcs = helpers.funcs
+local meths = helpers.meths
 
 if helpers.pending_win32(pending) then return end
 
+local fname = 'Xtest-functional-ex_cmds-write'
+local fname_bak = fname .. '~'
+local fname_broken = fname_bak .. 'broken'
+
 describe(':write', function()
   local function cleanup()
     os.remove('test_bkc_file.txt')
     os.remove('test_bkc_link.txt')
     os.remove('test_fifo')
+    os.remove(fname)
+    os.remove(fname_bak)
+    os.remove(fname_broken)
   end
   before_each(function()
     clear()
@@ -63,4 +76,34 @@ describe(':write', function()
     eq(text.."\n", fifo:read("*all"))
     fifo:close()
   end)
+
+  it('errors out correctly', function()
+    command('let $HOME=""')
+    eq(funcs.fnamemodify('.', ':p:h'), funcs.fnamemodify('.', ':p:h:~'))
+    -- Message from check_overwrite
+    eq(('\nE17: "'..funcs.fnamemodify('.', ':p:h')..'" is a directory'),
+       redir_exec('write .'))
+    meths.set_option('writeany', true)
+    -- Message from buf_write
+    eq(('\nE502: "." is a directory'),
+       redir_exec('write .'))
+    funcs.mkdir(fname_bak)
+    meths.set_option('backupdir', '.')
+    meths.set_option('backup', true)
+    write_file(fname, 'content0')
+    eq(0, exc_exec('edit ' .. fname))
+    funcs.setline(1, 'TTY')
+    eq('Vim(write):E510: Can\'t make backup file (add ! to override)',
+       exc_exec('write'))
+    meths.set_option('backup', false)
+    funcs.setfperm(fname, 'r--------')
+    eq('Vim(write):E505: "Xtest-functional-ex_cmds-write" is read-only (add ! to override)',
+       exc_exec('write'))
+    os.remove(fname)
+    os.remove(fname_bak)
+    write_file(fname_bak, 'TTYX')
+    lfs.link(fname_bak .. ('/xxxxx'):rep(20), fname, true)
+    eq('Vim(write):E166: Can\'t open linked file for writing',
+       exc_exec('write!'))
+  end)
 end)

test/functional/ui/cursor_spec.lua

@@ -1,8 +1,7 @@
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
-local clear, feed, meths = helpers.clear, helpers.feed, helpers.meths
+local clear, meths = helpers.clear, helpers.meths
-local insert, execute = helpers.insert, helpers.execute
+local eq = helpers.eq
-local eq, funcs = helpers.eq, helpers.funcs
 local command = helpers.command
 
 describe('ui/cursor', function()

test/unit/os/fileio_spec.lua

@@ -98,7 +98,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rwx------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rw------- file with kFileCreate', function()
@@ -106,7 +106,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rw-------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rwx------ file with kFileCreateOnly', function()
@@ -114,7 +114,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rwx------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rw------- file with kFileCreateOnly', function()
@@ -122,7 +122,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rw-------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('fails to open an existing file with kFileCreateOnly', function()
@@ -141,35 +141,35 @@ describe('file_open', function()
     local err, fp = file_open(file1, m.kFileCreate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with zero', function()
     local err, fp = file_open(file1, 0, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with kFileReadOnly', function()
     local err, fp = file_open(file1, m.kFileReadOnly, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with kFileNoSymlink', function()
     local err, fp = file_open(file1, m.kFileNoSymlink, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can truncate an existing file with kFileTruncate', function()
     local err, fp = file_open(file1, m.kFileTruncate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(0, attrs.size)
   end)
@@ -178,7 +178,7 @@ describe('file_open', function()
     local err, fp = file_open(file1, m.kFileWriteOnly, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(4096, attrs.size)
   end)
@@ -195,7 +195,7 @@ describe('file_open', function()
     local err, fp = file_open(linkf, m.kFileTruncate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(0, attrs.size)
   end)
@@ -221,7 +221,7 @@ describe('file_open_new', function()
     local err, fp = file_open_new(file1, 0, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_free(fp))
+    eq(0, m.file_free(fp, false))
   end)
 
   itp('fails to open an existing file with kFileCreateOnly', function()
@@ -231,7 +231,29 @@ describe('file_open_new', function()
   end)
 end)
 
--- file_close is called above, so it is not tested directly
+describe('file_close', function()
+  itp('can flush writes to disk also with true argument', function()
+    local err, fp = file_open(filec, m.kFileCreateOnly, 384)
+    eq(0, err)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, m.file_close(fp, true))
+    eq(wsize, lfs.attributes(filec).size)
+  end)
+end)
+
+describe('file_free', function()
+  itp('can flush writes to disk also with true argument', function()
+    local err, fp = file_open_new(filec, m.kFileCreateOnly, 384)
+    eq(0, err)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, m.file_free(fp, true))
+    eq(wsize, lfs.attributes(filec).size)
+  end)
+end)
 
 describe('file_fsync', function()
   itp('can flush writes to disk', function()
@@ -244,7 +266,7 @@ describe('file_fsync', function()
     eq(0, lfs.attributes(filec).size)
     eq(0, file_fsync(fp))
     eq(wsize, lfs.attributes(filec).size)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)
 
@@ -259,7 +281,7 @@ describe('file_flush', function()
     eq(0, lfs.attributes(filec).size)
     eq(0, file_flush(fp))
     eq(wsize, lfs.attributes(filec).size)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)
 
@@ -281,7 +303,7 @@ describe('file_read', function()
       eq({exp_err, exp_s}, {file_read(fp, size)})
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read the whole file at once', function()
@@ -290,7 +312,7 @@ describe('file_read', function()
     eq(false, fp.wr)
     eq({#fcontents, fcontents}, {file_read(fp, #fcontents)})
     eq({0, ('\0'):rep(#fcontents)}, {file_read(fp, #fcontents)})
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read more then 1024 bytes after reading a small chunk', function()
@@ -300,7 +322,7 @@ describe('file_read', function()
     eq({5, fcontents:sub(1, 5)}, {file_read(fp, 5)})
     eq({#fcontents - 5, fcontents:sub(6) .. (('\0'):rep(5))},
        {file_read(fp, #fcontents)})
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read file by 768-byte-chunks', function()
@@ -320,7 +342,7 @@ describe('file_read', function()
       eq({exp_err, exp_s}, {file_read(fp, size)})
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)
 
@@ -331,7 +353,7 @@ describe('file_write', function()
     eq(true, fp.wr)
     local wr = file_write(fp, fcontents)
     eq(#fcontents, wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(wr, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -348,7 +370,7 @@ describe('file_write', function()
       eq(wr, #s)
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(#fcontents, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -365,7 +387,7 @@ describe('file_write', function()
       eq(wr, #s)
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(#fcontents, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -380,6 +402,6 @@ describe('file_skip', function()
     local rd, s = file_read(fp, 3)
     eq(3, rd)
     eq(fcontents:sub(4, 6), s)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)