iconvconfig: Fix behaviour with --prefix [BZ #28199]

The consolidation of configuration parsing broke behaviour with
--prefix, where the prefix bled into the modules cache.  Accept a
prefix which, when non-NULL, is prepended to the path when looking for
configuration files but only the original directory is added to the
modules cache.

This has no effect on the codegen of gconv_conf since it passes NULL.

Reported-by: Patrick McCarty <patrick.mccarty@intel.com>
Reported-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>

1 files changed, 15 insertions, 7 deletions

diff --git a/iconv/gconv_parseconfdir.h b/iconv/gconv_parseconfdir.h
index 2f062689ec..a586268abc 100644
--- a/iconv/gconv_parseconfdir.h
+++ b/iconv/gconv_parseconfdir.h
@@ -39,7 +39,6 @@
 /* Name of the file containing the module information in the directories
    along the path.  */
 static const char gconv_conf_filename[] = "gconv-modules";
-static const char gconv_conf_dirname[] = "gconv-modules.d";
 
 static void add_alias (char *);
 static void add_module (char *, const char *, size_t, int);
@@ -110,19 +109,28 @@ read_conf_file (const char *filename, const char *directory, size_t dir_len)
   return true;
 }
 
+/* Prefix DIR (with length DIR_LEN) with PREFIX if the latter is non-NULL and
+   parse configuration in it.  */
+
 static __always_inline bool
-gconv_parseconfdir (const char *dir, size_t dir_len)
+gconv_parseconfdir (const char *prefix, const char *dir, size_t dir_len)
 {
-  /* No slash needs to be inserted between dir and gconv_conf_filename;
-     dir already ends in a slash.  */
-  char *buf = malloc (dir_len + sizeof (gconv_conf_dirname));
+  /* No slash needs to be inserted between dir and gconv_conf_filename; dir
+     already ends in a slash.  The additional 2 is to accommodate the ".d"
+     when looking for configuration files in gconv-modules.d.  */
+  size_t buflen = dir_len + sizeof (gconv_conf_filename) + 2;
+  char *buf = malloc (buflen + (prefix != NULL ? strlen (prefix) : 0));
+  char *cp = buf;
   bool found = false;
 
   if (buf == NULL)
     return false;
 
-  char *cp = mempcpy (mempcpy (buf, dir, dir_len), gconv_conf_filename,
-		      sizeof (gconv_conf_filename));
+  if (prefix != NULL)
+    cp = stpcpy (cp, prefix);
+
+  cp = mempcpy (mempcpy (cp, dir, dir_len), gconv_conf_filename,
+		sizeof (gconv_conf_filename));
 
   /* Read the gconv-modules configuration file first.  */
   found = read_conf_file (buf, dir, dir_len);