gconv_conf: Split out configuration file processing

Split configuration file processing into a separate header file and
include it.  Macroize all calls that need to go through internal
interfaces so that iconvconfig can also use them.

Reviewed-by: DJ Delorie <dj@redhat.com>

1 files changed, 161 insertions, 0 deletions

diff --git a/iconv/gconv_parseconfdir.h b/iconv/gconv_parseconfdir.h
new file mode 100644
index 0000000000..3d4d58d4be
--- /dev/null
+++ b/iconv/gconv_parseconfdir.h
@@ -0,0 +1,161 @@
+/* Handle configuration data.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+#include <libc-symbols.h>
+#include <locale.h>
+#include <sys/types.h>
+
+#if IS_IN (libc)
+# include <libio/libioP.h>
+# define __getdelim(line, len, c, fp) _IO_getdelim (line, len, c, fp)
+
+# undef isspace
+# define isspace(__c) __isspace_l ((__c), _nl_C_locobj_ptr)
+# define asprintf __asprintf
+# define opendir __opendir
+# define readdir __readdir
+# define closedir __closedir
+# define mempcpy __mempcpy
+#endif
+
+/* 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);
+
+/* Read the next configuration file.  */
+static bool
+read_conf_file (const char *filename, const char *directory, size_t dir_len)
+{
+  /* Note the file is opened with cancellation in the I/O functions
+     disabled.  */
+  FILE *fp = fopen (filename, "rce");
+  char *line = NULL;
+  size_t line_len = 0;
+  static int modcounter;
+
+  /* Don't complain if a file is not present or readable, simply silently
+     ignore it.  */
+  if (fp == NULL)
+    return false;
+
+  /* No threads reading from this stream.  */
+  __fsetlocking (fp, FSETLOCKING_BYCALLER);
+
+  /* Process the known entries of the file.  Comments start with `#' and
+     end with the end of the line.  Empty lines are ignored.  */
+  while (!__feof_unlocked (fp))
+    {
+      char *rp, *endp, *word;
+      ssize_t n = __getdelim (&line, &line_len, '\n', fp);
+      if (n < 0)
+	/* An error occurred.  */
+	break;
+
+      rp = line;
+      /* Terminate the line (excluding comments or newline) by an NUL byte
+	 to simplify the following code.  */
+      endp = strchr (rp, '#');
+      if (endp != NULL)
+	*endp = '\0';
+      else
+	if (rp[n - 1] == '\n')
+	  rp[n - 1] = '\0';
+
+      while (isspace (*rp))
+	++rp;
+
+      /* If this is an empty line go on with the next one.  */
+      if (rp == endp)
+	continue;
+
+      word = rp;
+      while (*rp != '\0' && !isspace (*rp))
+	++rp;
+
+      if (rp - word == sizeof ("alias") - 1
+	  && memcmp (word, "alias", sizeof ("alias") - 1) == 0)
+	add_alias (rp);
+      else if (rp - word == sizeof ("module") - 1
+	       && memcmp (word, "module", sizeof ("module") - 1) == 0)
+	add_module (rp, directory, dir_len, modcounter++);
+      /* else */
+	/* Otherwise ignore the line.  */
+    }
+
+  free (line);
+
+  fclose (fp);
+  return true;
+}
+
+static __always_inline bool
+gconv_parseconfdir (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));
+  bool found = false;
+
+  if (buf == NULL)
+    return false;
+
+  char *cp = mempcpy (mempcpy (buf, 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);
+
+  /* Next, see if there is a gconv-modules.d directory containing
+     configuration files and if it is non-empty.  */
+  cp--;
+  cp[0] = '.';
+  cp[1] = 'd';
+  cp[2] = '\0';
+
+  DIR *confdir = opendir (buf);
+  if (confdir != NULL)
+    {
+      struct dirent *ent;
+      while ((ent = readdir (confdir)) != NULL)
+	{
+	  if (ent->d_type != DT_REG)
+	    continue;
+
+	  size_t len = strlen (ent->d_name);
+	  const char *suffix = ".conf";
+
+	  if (len > strlen (suffix)
+	      && strcmp (ent->d_name + len - strlen (suffix), suffix) == 0)
+	    {
+	      char *conf;
+	      if (asprintf (&conf, "%s/%s", buf, ent->d_name) < 0)
+		continue;
+	      found |= read_conf_file (conf, dir, dir_len);
+	      free (conf);
+	    }
+	}
+      closedir (confdir);
+    }
+  free (buf);
+  return found;
+}