stdpaths,main: Remove all remaining memory leaks

src/nvim/main.c

@@ -1895,6 +1895,7 @@ static void source_startup_scripts(mparm_T *parmp)
           (void)do_source((char_u *)EXRC_FILE, FALSE, DOSO_NONE);
       }
     }
+    xfree(user_vimrc);
     if (secure == 2)
       need_wait_return = TRUE;
     secure = 0;

src/nvim/os/stdpaths.c

@@ -59,7 +59,7 @@ static char *get_xdg_home(const XDGVarType idx)
 {
   char *dir = stdpaths_get_xdg_var(idx);
   if (dir) {
-    dir = concat_fnames(dir, "nvim", true);
+    dir = concat_fnames_realloc(dir, "nvim", true);
   }
   return dir;
 }
@@ -77,13 +77,13 @@ static void create_dir(const char *dir, int mode, const char *suffix)
 char *stdpaths_user_conf_subpath(const char *fname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
 {
-  return concat_fnames(get_xdg_home(kXDGConfigHome), fname, true);
+  return concat_fnames_realloc(get_xdg_home(kXDGConfigHome), fname, true);
 }
 
 char *stdpaths_user_data_subpath(const char *fname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
 {
-  char *dir = concat_fnames(get_xdg_home(kXDGDataHome), fname, true);
+  char *dir = concat_fnames_realloc(get_xdg_home(kXDGDataHome), fname, true);
   if (!os_isdir((char_u *)dir)) {
     create_dir(dir, 0755, fname);
   }

src/nvim/path.c

@@ -329,6 +329,31 @@ int vim_fnamencmp(char_u *x, char_u *y, size_t len)
 #endif
 }
 
+/// Append fname2 to fname1
+///
+/// @param[in]  fname1  First fname to append to.
+/// @param[in]  len1    Length of fname1.
+/// @param[in]  fname2  Secord part of the file name.
+/// @param[in]  len2    Length of fname2.
+/// @param[in]  sep     If true and fname1 does not end with a path separator,
+///                     add a path separator before fname2.
+///
+/// @return fname1
+static inline char *do_concat_fnames(char *fname1, const size_t len1,
+                                     const char *fname2, const size_t len2,
+                                     const bool sep)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
+{
+  if (sep && *fname1 && !after_pathsep(fname1, fname1 + len1)) {
+    fname1[len1] = PATHSEP;
+    memmove(fname1 + len1 + 1, fname2, len2 + 1);
+  } else {
+    memmove(fname1 + len1, fname2, len2 + 1);
+  }
+
+  return fname1;
+}
+
 /// Concatenate file names fname1 and fname2 into allocated memory.
 ///
 /// Only add a '/' or '\\' when 'sep' is true and it is necessary.
@@ -341,15 +366,30 @@ int vim_fnamencmp(char_u *x, char_u *y, size_t len)
 char *concat_fnames(const char *fname1, const char *fname2, bool sep)
   FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_NONNULL_RET
 {
-  char *dest = xmalloc(strlen(fname1) + strlen(fname2) + 3);
-
-  strcpy(dest, fname1);
-  if (sep) {
-    add_pathsep(dest);
+  const size_t len1 = strlen(fname1);
+  const size_t len2 = strlen(fname2);
+  char *dest = xmalloc(len1 + len2 + 3);
+  memmove(dest, fname1, len1 + 1);
+  return do_concat_fnames(dest, len1, fname2, len2, sep);
 }
-  strcat(dest, fname2);
 
-  return dest;
+/// Concatenate file names fname1 and fname2
+///
+/// Like concat_fnames(), but in place of allocating new memory it reallocates
+/// fname1. For this reason fname1 must be allocated with xmalloc.
+///
+/// @param fname1 is the first part of the path or filename
+/// @param fname2 is the second half of the path or filename
+/// @param sep    is a flag to indicate a path separator should be added
+///               if necessary
+/// @return [allocated] Concatenation of fname1 and fname2.
+char *concat_fnames_realloc(char *fname1, const char *fname2, bool sep)
+  FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_NONNULL_RET
+{
+  const size_t len1 = strlen(fname1);
+  const size_t len2 = strlen(fname2);
+  return do_concat_fnames(xrealloc(fname1, len1 + len2 + 3), len1,
+                          fname2, len2, sep);
 }
 
 /*