sysdeps/generic/dl-tunables-parse.h

   1 /* Helper functions to handle tunable strings.
   2    Copyright (C) 2023-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _DL_TUNABLES_PARSE_H
  20 #define _DL_TUNABLES_PARSE_H 1
  21
  22 #include <assert.h>
  23 #include <string.h>
  24
  25 /* Compare the contents of STRVAL with STR of size LEN.  The STR might not
  26    be null-terminated.   */
  27 static __always_inline bool
  28 tunable_strcmp (const struct tunable_str_t *strval, const char *str,
  29                 size_t len)
  30 {
  31   return strval->len == len && memcmp (strval->str, str, len) == 0;
  32 }
  33 #define tunable_strcmp_cte(__tunable, __str) \
  34  tunable_strcmp (&__tunable->strval, __str, sizeof (__str) - 1)
  35
  36 /*
  37    Helper functions to iterate over a tunable string composed by multiple
  38    suboptions separated by commaxi; this is a common pattern for CPU.  Each
  39    suboptions is return in the form of { address, size } (no null terminated).
  40    For instance:
  41
  42      struct tunable_str_comma_t ts;
  43      tunable_str_comma_init (&ts, valp);
  44
  45      struct tunable_str_t t;
  46      while (tunable_str_comma_next (&ts, &t))
  47       {
  48         _dl_printf ("[%s] %.*s (%d)\n",
  49                     __func__,
  50                     (int) tstr.len,
  51                     tstr.str,
  52                     (int) tstr.len);
  53
  54         if (tunable_str_comma_strcmp (&t, opt, opt1_len))
  55           {
  56             [...]
  57           }
  58         else if (tunable_str_comma_strcmp_cte (&t, "opt2"))
  59           {
  60             [...]
  61           }
  62       }
  63
  64    NB: These function are expected to be called from tunable callback
  65    functions along with tunable_val_t with string types.
  66 */
  67
  68 struct tunable_str_comma_state_t
  69 {
  70   const char *p;
  71   size_t plen;
  72   size_t maxplen;
  73 };
  74
  75 struct tunable_str_comma_t
  76 {
  77   const char *str;
  78   size_t len;
  79   bool disable;
  80 };
  81
  82 static inline void
  83 tunable_str_comma_init (struct tunable_str_comma_state_t *state,
  84                         tunable_val_t *valp)
  85 {
  86   assert (valp->strval.str != NULL);
  87   state->p = valp->strval.str;
  88   state->plen = 0;
  89   state->maxplen = valp->strval.len;
  90 }
  91
  92 static inline bool
  93 tunable_str_comma_next (struct tunable_str_comma_state_t *state,
  94                         struct tunable_str_comma_t *str)
  95 {
  96   if (*state->p == '\0' || state->plen >= state->maxplen)
  97     return false;
  98
  99   const char *c;
 100   for (c = state->p; *c != ','; c++, state->plen++)
 101     if (*c == '\0' || state->plen == state->maxplen)
 102       break;
 103
 104   str->str = state->p;
 105   str->len = c - state->p;
 106
 107   if (str->len > 0)
 108     {
 109       str->disable = *str->str == '-';
 110       if (str->disable)
 111         {
 112           str->str = str->str + 1;
 113           str->len = str->len - 1;
 114         }
 115     }
 116
 117   state->p = c + 1;
 118   state->plen++;
 119
 120   return true;
 121 }
 122
 123 /* Compare the contents of T with STR of size LEN.  The STR might not be
 124    null-terminated.   */
 125 static __always_inline bool
 126 tunable_str_comma_strcmp (const struct tunable_str_comma_t *t, const char *str,
 127                           size_t len)
 128 {
 129   return t->len == len && memcmp (t->str, str, len) == 0;
 130 }
 131 #define tunable_str_comma_strcmp_cte(__t, __str) \
 132   tunable_str_comma_strcmp (__t, __str, sizeof (__str) - 1)
 133
 134 #endif