fileio: Refactor msg_add_fname to something which needs no comments

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/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
@@ -3531,8 +3527,8 @@ 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;
@@ -3681,10 +3677,11 @@ nofail:
 #endif
 
   if (errmsg != NULL) {
+    // - 100 to save some space for further error message
 #ifndef UNIX
-    msg_add_fname(buf, sfname);
+    add_quoted_fname((char *)IObuff, IOSIZE - 100, buf, (const char *)sfname);
 #else
-    msg_add_fname(buf, fname);
+    add_quoted_fname((char *)IObuff, IOSIZE - 100, buf, (const char *)fname);
 #endif
     if (errnum != NULL) {
       if (errmsgarg != 0) {
@@ -3811,16 +3808,25 @@ 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 `~`.
-static 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/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/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;
 }
 
 /*