vim-patch:9.2.0506: home_replace() function can be improved (#39925)

Problem:  home_replace() function can be improved
Solution: Refactor home_replace() to return the length of the string
          (John Marriott).

In addition:
- in function set_b0_fname() move ulen into the block where it is used.
- In function findswapname() rework logic around displaying "swap file
  already exists" dialogue so that literal message text is set once.

closes: vim/vim#20249

https://github.com/vim/vim/commit/a0931a90eeee6692556f330b5ba1fb413f9ea85d

Co-authored-by: John Marriott <basilisk@internode.on.net>

5 files changed, 22 insertions, 19 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 5ef7cda17a..09993d03de 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -3317,9 +3317,8 @@ void fileinfo(int fullname, int shorthelp, bool dont_truncate)
                                       IOSIZE - bufferlen, "%s", name);
   } else {
     name = (!fullname && curbuf->b_fname != NULL) ? curbuf->b_fname : curbuf->b_ffname;
-    home_replace(shorthelp ? curbuf : NULL, name, buffer + bufferlen,
-                 IOSIZE - bufferlen, true);
-    bufferlen += strlen(buffer + bufferlen);
+    bufferlen += home_replace(shorthelp ? curbuf : NULL, name,
+                              buffer + bufferlen, IOSIZE - bufferlen, true);
   }
 
   bool dontwrite = bt_dontwrite(curbuf);
diff --git a/src/nvim/eval/fs.c b/src/nvim/eval/fs.c
index 8bf7414d8e..121897c84b 100644
--- a/src/nvim/eval/fs.c
+++ b/src/nvim/eval/fs.c
@@ -161,19 +161,24 @@ repeat:
     has_fullname = false;
 
     if (p != NULL) {
+      size_t dirnamelen = 0;
+
       if (c == '.') {
         os_dirname(dirname, MAXPATHL);
         if (has_homerelative) {
           s = xstrdup(dirname);
-          home_replace(NULL, s, dirname, MAXPATHL, true);
+          dirnamelen = home_replace(NULL, s, dirname, MAXPATHL, true);
           xfree(s);
         }
-        size_t namelen = strlen(dirname);
+
+        if (dirnamelen == 0) {
+          dirnamelen = strlen(dirname);
+        }
 
         // Do not call shorten_fname() here since it removes the prefix
         // even though the path does not have a prefix.
-        if (path_fnamencmp(p, dirname, namelen) == 0) {
-          p += namelen;
+        if (path_fnamencmp(p, dirname, dirnamelen) == 0) {
+          p += dirnamelen;
           if (vim_ispathsep(*p)) {
             while (*p && vim_ispathsep(*p)) {
               p++;
@@ -188,10 +193,10 @@ repeat:
           }
         }
       } else {
-        home_replace(NULL, p, dirname, MAXPATHL, true);
+        dirnamelen = home_replace(NULL, p, dirname, MAXPATHL, true);
         // Only replace it when it starts with '~'
         if (*dirname == '~') {
-          s = xstrdup(dirname);
+          s = xmemdupz(dirname, dirnamelen);
           assert(s != NULL);  // suppress clang "Argument with 'nonnull' attribute passed null"
           *fnamep = s;
           xfree(*bufp);
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 7b0d4c6d26..1b6c6e44ba 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -2154,19 +2154,20 @@ int set_rw_fname(char *fname, char *sfname)
 /// Replaces home directory at the start with `~`.
 ///
 /// @param[out]  ret_buf  Buffer to save results to.
-/// @param[in]  buf_len  ret_buf length.
+/// @param[in]  bufsize  ret_buf size.
 /// @param[in]  buf  buf_T file name is coming from.
 /// @param[in]  fname  File name to write.
-void add_quoted_fname(char *const ret_buf, const size_t buf_len, const buf_T *const buf,
+void add_quoted_fname(char *const ret_buf, const size_t bufsize, const buf_T *const buf,
                       const char *fname)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   if (fname == NULL) {
     fname = "-stdin-";
   }
-  ret_buf[0] = '"';
-  home_replace(buf, fname, ret_buf + 1, buf_len - 4, true);
-  xstrlcat(ret_buf, "\" ", buf_len);
+  size_t len = 0;
+  ret_buf[len++] = '"';
+  len += home_replace(buf, fname, ret_buf + len, bufsize - 4, true);
+  xstrlcpy(ret_buf + len, "\" ", bufsize - len);
 }
 
 /// Append message for text mode to IObuff.
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 371b4013c8..a4ec90fd95 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -669,13 +669,12 @@ static void set_b0_fname(ZeroBlock *b0p, buf_T *buf)
     // editing the same file on different machines over a network.
     // First replace home dir path with "~/" with home_replace().
     // Then insert the user name to get "~user/".
-    home_replace(NULL, buf->b_ffname, b0p->b0_fname,
-                 B0_FNAME_SIZE_CRYPT, true);
+    size_t flen = home_replace(NULL, buf->b_ffname, b0p->b0_fname,
+                               B0_FNAME_SIZE_CRYPT, true);
     if (b0p->b0_fname[0] == '~') {
       // If there is no user name or it is too long, don't use "~/"
       int retval = os_get_username(uname, B0_UNAME_SIZE);
       size_t ulen = strlen(uname);
-      size_t flen = strlen(b0p->b0_fname);
       if (retval == FAIL || ulen + flen > B0_FNAME_SIZE_CRYPT - 1) {
         xstrlcpy(b0p->b0_fname, buf->b_ffname, B0_FNAME_SIZE_CRYPT);
       } else {
diff --git a/src/nvim/shada.c b/src/nvim/shada.c
index 4ca8ead9fa..3d0ef49bf8 100644
--- a/src/nvim/shada.c
+++ b/src/nvim/shada.c
@@ -3538,8 +3538,7 @@ static bool shada_removable(const char *name)
   for (char *p = p_shada; *p;) {
     copy_option_part(&p, part, ARRAY_SIZE(part), ", ");
     if (part[0] == 'r') {
-      home_replace(NULL, part + 1, NameBuff, MAXPATHL, true);
-      size_t n = strlen(NameBuff);
+      size_t n = home_replace(NULL, part + 1, NameBuff, MAXPATHL, true);
       if (mb_strnicmp(NameBuff, new_name, n) == 0) {
         retval = true;
         break;