Act like POSIX sh if $HOME is relative

POSIX says sh ~/foo should act like $HOME/foo even if $HOME is
relative, so be consistent with that (Bug#33255).
* admin/merge-gnulib (GNULIB_MODULES): Add dosname.
* src/buffer.c (init_buffer): Use emacs_wd to get
initial working directory with slash appended if needed.
(default-directory): Say it must be absolute.
* src/emacs.c (emacs_wd): New global variable.
(init_cmdargs): Dir arg is now char const *.
(main): Set emacs_wd.
* src/emacs.c (main) [NS_IMPL_COCOA]:
* src/fileio.c (Fexpand_file_name):
Use get_homedir instead of egetenv ("HOME").
* src/fileio.c: Include dosname.h, for IS_ABSOLUTE_FILE_NAME.
(splice_dir_file, get_homedir): New functions.
* src/xrdb.c (gethomedir): Remove.  All callers changed
to use get_homedir and splice_dir_file.
* test/src/fileio-tests.el (fileio-tests--relative-HOME): New test.

1 files changed, 11 insertions, 43 deletions

diff --git a/src/xrdb.c b/src/xrdb.c
index 4abf1ad84ed..87c2faf6598 100644
--- a/src/xrdb.c
+++ b/src/xrdb.c
@@ -202,35 +202,6 @@ magic_db (const char *string, ptrdiff_t string_len, const char *class,
 }
 
 
-static char *
-gethomedir (void)
-{
-  struct passwd *pw;
-  char *ptr;
-  char *copy;
-
-  if ((ptr = getenv ("HOME")) == NULL)
-    {
-      if ((ptr = getenv ("LOGNAME")) != NULL
-	  || (ptr = getenv ("USER")) != NULL)
-	pw = getpwnam (ptr);
-      else
-	pw = getpwuid (getuid ());
-
-      if (pw)
-	ptr = pw->pw_dir;
-    }
-
-  if (ptr == NULL)
-    return xstrdup ("/");
-
-  ptrdiff_t len = strlen (ptr);
-  copy = xmalloc (len + 2);
-  strcpy (copy + len, "/");
-  return memcpy (copy, ptr, len);
-}
-
-
 /* Find the first element of SEARCH_PATH which exists and is readable,
    after expanding the %-escapes.  Return 0 if we didn't find any, and
    the path name of the one we found otherwise.  */
@@ -316,12 +287,11 @@ get_user_app (const char *class)
   if (! db)
     {
       /* Check in the home directory.  This is a bit of a hack; let's
-	 hope one's home directory doesn't contain any %-escapes.  */
-      char *home = gethomedir ();
+	 hope one's home directory doesn't contain ':' or '%'.  */
+      char const *home = get_homedir ();
       db = search_magic_path (home, class, "%L/%N");
       if (! db)
 	db = search_magic_path (home, class, "%N");
-      xfree (home);
     }
 
   return db;
@@ -346,10 +316,9 @@ get_user_db (Display *display)
   else
     {
       /* Use ~/.Xdefaults.  */
-      char *home = gethomedir ();
-      ptrdiff_t homelen = strlen (home);
-      char *filename = xrealloc (home, homelen + sizeof xdefaults);
-      strcpy (filename + homelen, xdefaults);
+      char const *home = get_homedir ();
+      char *filename = xmalloc (strlen (home) + 1 + sizeof xdefaults);
+      splice_dir_file (filename, home, xdefaults);
       db = XrmGetFileDatabase (filename);
       xfree (filename);
     }
@@ -380,13 +349,12 @@ get_environ_db (void)
       if (STRINGP (system_name))
 	{
 	  /* Use ~/.Xdefaults-HOSTNAME.  */
-	  char *home = gethomedir ();
-	  ptrdiff_t homelen = strlen (home);
-	  ptrdiff_t filenamesize = (homelen + sizeof xdefaults
-				    + 1 + SBYTES (system_name));
-	  p = filename = xrealloc (home, filenamesize);
-	  lispstpcpy (stpcpy (stpcpy (filename + homelen, xdefaults), "-"),
-		      system_name);
+	  char const *home = get_homedir ();
+	  p = filename = xmalloc (strlen (home) + 1 + sizeof xdefaults
+				  + 1 + SBYTES (system_name));
+	  char *e = splice_dir_file (p, home, xdefaults);
+	  *e++ = '/';
+	  lispstpcpy (e, system_name);
 	}
     }