/*
 * Copyright © 2010 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <assert.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

/* Some versions of MinGW are missing _vscprintf's declaration, although they
 * still provide the symbol in the import library. */
#ifdef __MINGW32__
_CRTIMP int _vscprintf(const char *format, va_list argptr);
#endif

#include "ralloc.h"

#ifndef va_copy
#ifdef __va_copy
#define va_copy(dest, src) __va_copy((dest), (src))
#else
#define va_copy(dest, src) (dest) = (src)
#endif
#endif

#define CANARY 0x5A1106

struct ralloc_header
{
   /* A canary value used to determine whether a pointer is ralloc'd. */
   unsigned canary;

   struct ralloc_header *parent;

   /* The first child (head of a linked list) */
   struct ralloc_header *child;

   /* Linked list of siblings */
   struct ralloc_header *prev;
   struct ralloc_header *next;

   void (*destructor)(void *);
};

typedef struct ralloc_header ralloc_header;

static void unlink_block(ralloc_header *info);
static void unsafe_free(ralloc_header *info);

static ralloc_header *
get_header(const void *ptr)
{
   ralloc_header *info = (ralloc_header *) (((char *) ptr) -
					    sizeof(ralloc_header));
   assert(info->canary == CANARY);
   return info;
}

#define PTR_FROM_HEADER(info) (((char *) info) + sizeof(ralloc_header))

static void
add_child(ralloc_header *parent, ralloc_header *info)
{
   if (parent != NULL) {
      info->parent = parent;
      info->next = parent->child;
      parent->child = info;

      if (info->next != NULL)
	 info->next->prev = info;
   }
}

void *
ralloc_context(const void *ctx)
{
   return ralloc_size(ctx, 0);
}

void *
ralloc_size(const void *ctx, size_t size)
{
   void *block = calloc(1, size + sizeof(ralloc_header));

   ralloc_header *info = (ralloc_header *) block;
   ralloc_header *parent = ctx != NULL ? get_header(ctx) : NULL;

   add_child(parent, info);

   info->canary = CANARY;

   return PTR_FROM_HEADER(info);
}

void *
rzalloc_size(const void *ctx, size_t size)
{
   void *ptr = ralloc_size(ctx, size);
   if (likely(ptr != NULL))
      memset(ptr, 0, size);
   return ptr;
}

/* helper function - assumes ptr != NULL */
static void *
resize(void *ptr, size_t size)
{
   ralloc_header *child, *old, *info;

   old = get_header(ptr);
   info = realloc(old, size + sizeof(ralloc_header));

   if (info == NULL)
      return NULL;

   /* Update parent and sibling's links to the reallocated node. */
   if (info != old && info->parent != NULL) {
      if (info->parent->child == old)
	 info->parent->child = info;

      if (info->prev != NULL)
	 info->prev->next = info;

      if (info->next != NULL)
	 info->next->prev = info;
   }

   /* Update child->parent links for all children */
   for (child = info->child; child != NULL; child = child->next)
      child->parent = info;

   return PTR_FROM_HEADER(info);
}

void *
reralloc_size(const void *ctx, void *ptr, size_t size)
{
   if (unlikely(ptr == NULL))
      return ralloc_size(ctx, size);

   assert(ralloc_parent(ptr) == ctx);
   return resize(ptr, size);
}

void *
ralloc_array_size(const void *ctx, size_t size, unsigned count)
{
   if (count > SIZE_MAX/size)
      return NULL;

   return ralloc_size(ctx, size * count);
}

void *
rzalloc_array_size(const void *ctx, size_t size, unsigned count)
{
   if (count > SIZE_MAX/size)
      return NULL;

   return rzalloc_size(ctx, size * count);
}

void *
reralloc_array_size(const void *ctx, void *ptr, size_t size, unsigned count)
{
   if (count > SIZE_MAX/size)
      return NULL;

   return reralloc_size(ctx, ptr, size * count);
}

void
ralloc_free(void *ptr)
{
   ralloc_header *info;

   if (ptr == NULL)
      return;

   info = get_header(ptr);
   unlink_block(info);
   unsafe_free(info);
}

static void
unlink_block(ralloc_header *info)
{
   /* Unlink from parent & siblings */
   if (info->parent != NULL) {
      if (info->parent->child == info)
	 info->parent->child = info->next;

      if (info->prev != NULL)
	 info->prev->next = info->next;

      if (info->next != NULL)
	 info->next->prev = info->prev;
   }
   info->parent = NULL;
   info->prev = NULL;
   info->next = NULL;
}

static void
unsafe_free(ralloc_header *info)
{
   /* Recursively free any children...don't waste time unlinking them. */
   ralloc_header *temp;
   while (info->child != NULL) {
      temp = info->child;
      info->child = temp->next;
      unsafe_free(temp);
   }

   /* Free the block itself.  Call the destructor first, if any. */
   if (info->destructor != NULL)
      info->destructor(PTR_FROM_HEADER(info));

   free(info);
}

void
ralloc_steal(const void *new_ctx, void *ptr)
{
   ralloc_header *info, *parent;

   if (unlikely(ptr == NULL))
      return;

   info = get_header(ptr);
   parent = get_header(new_ctx);

   unlink_block(info);

   add_child(parent, info);
}

void *
ralloc_parent(const void *ptr)
{
   ralloc_header *info;

   if (unlikely(ptr == NULL))
      return NULL;

   info = get_header(ptr);
   return info->parent ? PTR_FROM_HEADER(info->parent) : NULL;
}

static void *autofree_context = NULL;

static void
autofree(void)
{
   ralloc_free(autofree_context);
}

void *
ralloc_autofree_context(void)
{
   if (unlikely(autofree_context == NULL)) {
      autofree_context = ralloc_context(NULL);
      atexit(autofree);
   }
   return autofree_context;
}

void
ralloc_set_destructor(const void *ptr, void(*destructor)(void *))
{
   ralloc_header *info = get_header(ptr);
   info->destructor = destructor;
}

char *
ralloc_strdup(const void *ctx, const char *str)
{
   size_t n;
   char *ptr;

   if (unlikely(str == NULL))
      return NULL;

   n = strlen(str);
   ptr = ralloc_array(ctx, char, n + 1);
   memcpy(ptr, str, n);
   ptr[n] = '\0';
   return ptr;
}

char *
ralloc_strndup(const void *ctx, const char *str, size_t max)
{
   size_t n;
   char *ptr;

   if (unlikely(str == NULL))
      return NULL;

   n = strlen(str);
   if (n > max)
      n = max;

   ptr = ralloc_array(ctx, char, n + 1);
   memcpy(ptr, str, n);
   ptr[n] = '\0';
   return ptr;
}

/* helper routine for strcat/strncat - n is the exact amount to copy */
static bool
cat(char **dest, const char *str, size_t n)
{
   char *both;
   size_t existing_length;
   assert(dest != NULL && *dest != NULL);

   existing_length = strlen(*dest);
   both = resize(*dest, existing_length + n + 1);
   if (unlikely(both == NULL))
      return false;

   memcpy(both + existing_length, str, n);
   both[existing_length + n] = '\0';

   *dest = both;
   return true;
}


bool
ralloc_strcat(char **dest, const char *str)
{
   return cat(dest, str, strlen(str));
}

bool
ralloc_strncat(char **dest, const char *str, size_t n)
{
   /* Clamp n to the string length */
   size_t str_length = strlen(str);
   if (str_length < n)
      n = str_length;

   return cat(dest, str, n);
}

char *
ralloc_asprintf(const void *ctx, const char *fmt, ...)
{
   char *ptr;
   va_list args;
   va_start(args, fmt);
   ptr = ralloc_vasprintf(ctx, fmt, args);
   va_end(args);
   return ptr;
}

/* Return the length of the string that would be generated by a printf-style
 * format and argument list, not including the \0 byte.
 */
static size_t
printf_length(const char *fmt, va_list untouched_args)
{
   int size;
   char junk;

   /* Make a copy of the va_list so the original caller can still use it */
   va_list args;
   va_copy(args, untouched_args);

#ifdef _WIN32
   /* We need to use _vcsprintf to calculate the size as vsnprintf returns -1
    * if the number of characters to write is greater than count.
    */
   size = _vscprintf(fmt, args);
   (void)junk;
#else
   size = vsnprintf(&junk, 1, fmt, args);
#endif
   assert(size >= 0);

   va_end(args);

   return size;
}

char *
ralloc_vasprintf(const void *ctx, const char *fmt, va_list args)
{
   size_t size = printf_length(fmt, args) + 1;

   char *ptr = ralloc_size(ctx, size);
   if (ptr != NULL)
      vsnprintf(ptr, size, fmt, args);

   return ptr;
}

bool
ralloc_asprintf_append(char **str, const char *fmt, ...)
{
   bool success;
   va_list args;
   va_start(args, fmt);
   success = ralloc_vasprintf_append(str, fmt, args);
   va_end(args);
   return success;
}

bool
ralloc_vasprintf_append(char **str, const char *fmt, va_list args)
{
   size_t existing_length;
   assert(str != NULL);
   existing_length = *str ? strlen(*str) : 0;
   return ralloc_vasprintf_rewrite_tail(str, &existing_length, fmt, args);
}

bool
ralloc_asprintf_rewrite_tail(char **str, size_t *start, const char *fmt, ...)
{
   bool success;
   va_list args;
   va_start(args, fmt);
   success = ralloc_vasprintf_rewrite_tail(str, start, fmt, args);
   va_end(args);
   return success;
}

bool
ralloc_vasprintf_rewrite_tail(char **str, size_t *start, const char *fmt,
			      va_list args)
{
   size_t new_length;
   char *ptr;

   assert(str != NULL);

   if (unlikely(*str == NULL)) {
      // Assuming a NULL context is probably bad, but it's expected behavior.
      *str = ralloc_vasprintf(NULL, fmt, args);
      return true;
   }

   new_length = printf_length(fmt, args);

   ptr = resize(*str, *start + new_length + 1);
   if (unlikely(ptr == NULL))
      return false;

   vsnprintf(ptr + *start, new_length + 1, fmt, args);
   *str = ptr;
   *start += new_length;
   return true;
}