common.h

/*
    Common macros and helpers.

    Copyright (C) 2017 Andrea Stacchiotti  <andreastacchiotti(a)gmail.com>

    This file is part of libscanmem.

    This 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 3 of the License, or
    (at your option) any later version.

    This 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 this library.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef COMMON_H
#define COMMON_H

#include <stdbool.h>
#include <sys/types.h>

#ifndef MIN
# define MIN(a,b) ((a) < (b) ? (a) : (b))
#endif

/* From `include/linux/compiler.h`, in the linux kernel:
 * Offers a simple interface to the expect builtin */
#ifdef __GNUC__
# define LIKELY(x)     __builtin_expect(!!(x), 1)
# define UNLIKELY(x)   __builtin_expect(!!(x), 0)
#else
# define LIKELY(x)     (x)
# define UNLIKELY(x)   (x)
#endif

/* from string.h in glibc for Android/BSD */
#ifndef strdupa
# include <alloca.h>
# include <string.h>
# define strdupa(s)                                                           \
    ({                                                                        \
      const char *__old = (s);                                                \
      size_t __len = strlen(__old) + 1;                                       \
      char *__new = (char *) alloca(__len);                                   \
      (char *) memcpy(__new, __old, __len);                                   \
    })
#endif

#ifndef strndupa
# include <alloca.h>
# include <string.h>
# define strndupa(s, n)                                                       \
    ({                                                                        \
      const char *__old = (s);                                                \
      size_t __len = strnlen(__old, (n));                                     \
      char *__new = (char *) alloca(__len + 1);                               \
      __new[__len] = '\0';                                                    \
      (char *) memcpy(__new, __old, __len);                                   \
    })
#endif

/* Use the best `getenv()` implementation we have */
#if HAVE_SECURE_GETENV
# define util_getenv secure_getenv
#else
# define util_getenv getenv
#endif

/* Function declarations */
bool sm_process_is_dead(pid_t pid);

#endif /* COMMON_H */