srn_mmap.h

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/* -*- C -*-
 * Serene programming language
 * Copyright (C) 2019-2026 Sameer Rahmani <lxsameer@lxsameer.com>
 *
 * 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 <https://www.gnu.org/licenses/>.
 */
 
// This implementation is based on libgit2's api
#pragma once
 
#include <stddef.h>
#include <stdio.h>
 
#include "serene/utils.h"
 
#if (defined(_WIN32)) && !defined(__CYGWIN__)
#  define PMAP_WIN32 1
#else
#  define PMAP_WIN32 0
#endif
 
#if PMAP_WIN32
#  include <windows.h>
#endif
 
/* srn_mmap() prot values */
#define SRN_PROT_NONE  0x0
#define SRN_PROT_READ  0x1
#define SRN_PROT_WRITE 0x2
#define SRN_PROT_EXEC  0x4
 
/* srn__mmmap() flags values */
#define SRN_MAP_FILE    0
#define SRN_MAP_SHARED  1
#define SRN_MAP_PRIVATE 2
#define SRN_MAP_TYPE    0xf
#define SRN_MAP_FIXED   0x10
 
typedef struct srn_context_t srn_context_t;
typedef struct srn_error_t srn_error_t;
 
/**
 * Memory mapped buffer
 */
typedef struct srn_mmap_buffer_t {
  /// data bytes
  void *data;
  /// data length
  size_t len;
 
#if PMAP_WIN32
  /// file mapping handle
  HANDLE fmh;
#endif
} srn_mmap_buffer_t;
 
#define SRN_MMAP_VALIDATE(out, len, prot, flags)                                      \
  do {                                                                                \
    PANIC_IF(                                                                         \
      (out) == nullptr || (len) == 0,                                                 \
      "mmap requires a non-null output buffer and a positive length"                  \
    );                                                                                \
    PANIC_IF(                                                                         \
      !(((prot) & SRN_PROT_WRITE) || ((prot) & SRN_PROT_READ)),                       \
      "mmap requires read or write protection"                                        \
    );                                                                                \
    PANIC_IF(((flags) & SRN_MAP_FIXED) != 0, "mmap does not support fixed mappings"); \
  } while (0)
 
extern srn_error_t *srn_mmap(
  srn_context_t *ctx, srn_mmap_buffer_t *out, size_t len, int prot, int flags, int fd,
  off64_t offset
);
extern int srn_munmap(srn_mmap_buffer_t *map);