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>

1 files changed, 11 insertions, 6 deletions

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);