1 files changed, 98 insertions, 0 deletions
diff --git a/sysdeps/generic/dl-tunables-parse.h b/sysdeps/generic/dl-tunables-parse.h
new file mode 100644
index 0000000000..83cecaf416
--- /dev/null
+++ b/sysdeps/generic/dl-tunables-parse.h
@@ -0,0 +1,98 @@
+/* Helper functions to handle tunable strings.
+   Copyright (C) 2023 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/>.  */
+
+#ifndef _DL_TUNABLES_PARSE_H
+#define _DL_TUNABLES_PARSE_H 1
+
+#ifndef DEFAULT_MEMCMP
+# define DEFAULT_MEMCMP memcmp
+#endif
+
+/* Compare the contents of STRVAL with STR of size LEN.  The STR might not
+   be null-terminated.   */
+static inline bool
+tunable_strcmp (const struct tunable_str_t *strval, const char *str,
+		size_t len)
+{
+  return strval->len == len && DEFAULT_MEMCMP (strval->str, str, len) == 0;
+}
+#define tunable_strcmp_cte(__tunable, __str)				\
+ ({									\
+    __builtin_constant_p (__str)					\
+    ? tunable_strcmp (&__tunable->strval, __str, sizeof (__str) - 1)	\
+    : tunable_strcmp (&__tunable->strval, __str, strlen (__str));	\
+ })
+
+/* Helper function to iterate over string tunable composed by multiple
+   suboptions separated by comma.  The tunable is represented as span (address
+   and size) from GLIBC_TUNABLES, so it might not be null terminated.
+
+   For instance, to print all the items:
+
+     struct tunable_str_comma_t st;
+     tunable_str_comma_init (&st, valp);
+
+     struct tunable_str_t tstr;
+     while (tunable_str_comma_next (&st, &tstr))
+      {
+        if (tstr.len == 0)
+	  continue;
+
+	_dl_printf ("[%s] %.*s (%d)\n", __func__,
+		    (int) tstr.len,
+		    tstr.str,
+		    (int) tstr.len);
+      }  */
+
+struct tunable_str_comma_t
+{
+  const char *p;
+  size_t plen;
+  size_t maxplen;
+};
+
+static inline void
+tunable_str_comma_init (struct tunable_str_comma_t *state, tunable_val_t *valp)
+{
+  state->p = valp->strval.str;
+  state->plen = 0;
+  state->maxplen = valp->strval.len;
+}
+
+static inline bool
+tunable_str_comma_next (struct tunable_str_comma_t *state,
+			struct tunable_str_t *str)
+{
+  if (*state->p == '\0' || state->plen >= state->maxplen)
+    return false;
+
+  const char *c;
+  for (c = state->p; *c != ','; c++, state->plen++)
+    if (*c == '\0' || state->plen == state->maxplen)
+      break;
+
+  str->str = state->p;
+  str->len = c - state->p;
+
+  state->p = c + 1;
+  state->plen++;
+
+  return true;
+}
+
+#endif