1 files changed, 134 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..b37be0443b
--- /dev/null
+++ b/sysdeps/generic/dl-tunables-parse.h
@@ -0,0 +1,134 @@
+/* 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
+
+#include <assert.h>
+#include <string.h>
+
+/* Compare the contents of STRVAL with STR of size LEN.  The STR might not
+   be null-terminated.   */
+static __always_inline bool
+tunable_strcmp (const struct tunable_str_t *strval, const char *str,
+		size_t len)
+{
+  return strval->len == len && memcmp (strval->str, str, len) == 0;
+}
+#define tunable_strcmp_cte(__tunable, __str) \
+ tunable_strcmp (&__tunable->strval, __str, sizeof (__str) - 1)
+
+/*
+   Helper functions to iterate over a tunable string composed by multiple
+   suboptions separated by commaxi; this is a common pattern for CPU.  Each
+   suboptions is return in the form of { address, size } (no null terminated).
+   For instance:
+
+     struct tunable_str_comma_t ts;
+     tunable_str_comma_init (&ts, valp);
+
+     struct tunable_str_t t;
+     while (tunable_str_comma_next (&ts, &t))
+      {
+	_dl_printf ("[%s] %.*s (%d)\n",
+		    __func__,
+		    (int) tstr.len,
+		    tstr.str,
+		    (int) tstr.len);
+
+        if (tunable_str_comma_strcmp (&t, opt, opt1_len))
+	  {
+	    [...]
+	  }
+	else if (tunable_str_comma_strcmp_cte (&t, "opt2"))
+	  {
+	    [...]
+	  }
+      }
+
+   NB: These function are expected to be called from tunable callback
+   functions along with tunable_val_t with string types.
+*/
+
+struct tunable_str_comma_state_t
+{
+  const char *p;
+  size_t plen;
+  size_t maxplen;
+};
+
+struct tunable_str_comma_t
+{
+  const char *str;
+  size_t len;
+  bool disable;
+};
+
+static inline void
+tunable_str_comma_init (struct tunable_str_comma_state_t *state,
+			tunable_val_t *valp)
+{
+  assert (valp->strval.str != NULL);
+  state->p = valp->strval.str;
+  state->plen = 0;
+  state->maxplen = valp->strval.len;
+}
+
+static inline bool
+tunable_str_comma_next (struct tunable_str_comma_state_t *state,
+			struct tunable_str_comma_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;
+
+  if (str->len > 0)
+    {
+      str->disable = *str->str == '-';
+      if (str->disable)
+	{
+	  str->str = str->str + 1;
+	  str->len = str->len - 1;
+	}
+    }
+
+  state->p = c + 1;
+  state->plen++;
+
+  return true;
+}
+
+/* Compare the contents of T with STR of size LEN.  The STR might not be
+   null-terminated.   */
+static __always_inline bool
+tunable_str_comma_strcmp (const struct tunable_str_comma_t *t, const char *str,
+			  size_t len)
+{
+  return t->len == len && memcmp (t->str, str, len) == 0;
+}
+#define tunable_str_comma_strcmp_cte(__t, __str) \
+  tunable_str_comma_strcmp (__t, __str, sizeof (__str) - 1)
+
+#endif