/*
 *  Linux内核诊断工具--工具通用调试缓冲区模块
 *  这是为了解决procfs/trace的问题而编写
 *
 * Copyright (C) 2020 Alibaba Ltd.
 *
 * 作者： Baoyou Xie <baoyou.xie@linux.alibaba.com>
 *
 * License terms: GNU General Public License (GPL) version 3
 */

#include <linux/uaccess.h>
#include <linux/vmalloc.h>

#include "trace_buffer.h"
// #include "internal.h"
#include "variant_buffer.h"

int init_diag_variant_buffer(struct diag_variant_buffer *buffer,
                             unsigned int buf_size) {
  int ret = 0;

  ret = -EINVAL;
  if (buf_size < 10 * DIAG_TRACE_BUF_SIZE)
    return ret;

  memset(buffer, 0, sizeof(struct diag_variant_buffer));
  buffer->buf_size = buf_size;
  spin_lock_init(&buffer->lock);
  mutex_init(&buffer->mutex);

  ret = 0;
  return ret;
}

int alloc_diag_variant_buffer(struct diag_variant_buffer *buffer) {
  int ret = -ENOMEM;
  char *buf1 = NULL, *buf2 = NULL, *buf3 = NULL;
  unsigned int buf_size;

  buf_size = buffer->buf_size;
  if (buffer->alloced)
    return 0;

  ret = -EINVAL;
  if (buf_size < 10 * DIAG_TRACE_BUF_SIZE)
    return ret;

  ret = -ENOMEM;
  buf1 = vmalloc(buf_size);
  if (!buf1)
    goto out_nomem;

  buf2 = vmalloc(buf_size);
  if (!buf2)
    goto out_nomem;

  buf3 = vmalloc(buf_size * 2);
  if (!buf3)
    goto out_nomem;

  memset(buf1, 0, buf_size);
  memset(buf2, 0, buf_size);
  memset(buf3, 0, buf_size * 2);
  buffer->buffers[0].data = buf1;
  buffer->buffers[1].data = buf2;
  buffer->product.data = buf3;

  buffer->alloced = 1;

  ret = 0;
  return ret;
out_nomem:
  if (buf1)
    vfree(buf1);
  if (buf2)
    vfree(buf2);
  if (buf3)
    vfree(buf3);

  return ret;
}

void destroy_diag_variant_buffer(struct diag_variant_buffer *buffer) {
  if (buffer->buffers[0].data)
    vfree(buffer->buffers[0].data);
  if (buffer->buffers[1].data)
    vfree(buffer->buffers[1].data);
  if (buffer->product.data)
    vfree(buffer->product.data);

  memset(buffer, 0, sizeof(struct diag_variant_buffer));
}

void discard_diag_variant_buffer(struct diag_variant_buffer *buffer) {
  unsigned long flags;

  if (!buffer->alloced)
    return;

  diag_variant_buffer_mutex_lock(buffer);
  diag_variant_buffer_spin_lock(buffer, flags);
  buffer->buffers[0].pos = buffer->buffers[1].pos = 0;
  buffer->buffer_toggle = 0;
  diag_variant_buffer_spin_unlock(buffer, flags);
  diag_variant_buffer_mutex_unlock(buffer);
}

void backup_diag_variant_buffer(struct diag_variant_buffer *buffer) {
  unsigned long flags;

  if (!buffer->alloced)
    return;

  diag_variant_buffer_mutex_lock(buffer);
  diag_variant_buffer_spin_lock(buffer, flags);

  buffer->product.len = 0;
  if (buffer->buffer_toggle == 0) {
    if (buffer->buffers[1].pos) {
      memcpy(buffer->product.data, buffer->buffers[1].data,
             buffer->buffers[1].pos);
      buffer->product.len = buffer->product.len + buffer->buffers[1].pos;
    }
    if (buffer->buffers[0].pos) {
      memcpy(buffer->product.data + buffer->product.len,
             buffer->buffers[0].data, buffer->buffers[0].pos);
      buffer->product.len = buffer->product.len + buffer->buffers[0].pos;
    }
  } else {
    if (buffer->buffers[0].pos) {
      memcpy(buffer->product.data, buffer->buffers[0].data,
             buffer->buffers[0].pos);
      buffer->product.len = buffer->product.len + buffer->buffers[0].pos;
    }
    if (buffer->buffers[1].pos) {
      memcpy(buffer->product.data + buffer->product.len,
             buffer->buffers[1].data, buffer->buffers[1].pos);
      buffer->product.len = buffer->product.len + buffer->buffers[1].pos;
    }
  }

  buffer->buffers[0].pos = buffer->buffers[1].pos = 0;
  buffer->buffers[0].head = buffer->buffers[1].head = NULL;
  buffer->buffer_toggle = 0;

  diag_variant_buffer_spin_unlock(buffer, flags);
  diag_variant_buffer_mutex_unlock(buffer);
}

asmlinkage int diag_variant_buffer_reserve(struct diag_variant_buffer *buffer,
                                           size_t len) {
  int real_len = (len + sizeof(unsigned long)) & (sizeof(unsigned long) - 1);
  real_len += sizeof(struct diag_variant_buffer_head);
  /**
   * 这样可以简单的略过整型溢出检查。
   */
  if (len > 1024 * 1024 * 1024)
    return len;
  if (!buffer->alloced)
    return len;

  if (buffer->buffer_toggle == 0) {
    if (buffer->buffers[0].pos + real_len >= buffer->buf_size) {
      buffer->buffer_toggle = 1;
      buffer->buffers[1].pos = sizeof(struct diag_variant_buffer_head);
      buffer->buffers[1].head = (void *)buffer->buffers[1].data;
      memset(buffer->buffers[1].head, 0,
             sizeof(struct diag_variant_buffer_head));
    } else {
      buffer->buffers[0].head =
          (void *)buffer->buffers[0].data + buffer->buffers[0].pos;
      memset(buffer->buffers[0].head, 0,
             sizeof(struct diag_variant_buffer_head));
      buffer->buffers[0].pos += sizeof(struct diag_variant_buffer_head);
    }
  } else {
    if (buffer->buffers[1].pos + real_len >= buffer->buf_size) {
      buffer->buffer_toggle = 0;
      buffer->buffers[0].pos = sizeof(struct diag_variant_buffer_head);
      buffer->buffers[0].head = (void *)buffer->buffers[0].data;
      memset(buffer->buffers[0].head, 0,
             sizeof(struct diag_variant_buffer_head));
    } else {
      buffer->buffers[1].head =
          (void *)buffer->buffers[1].data + buffer->buffers[1].pos;
      memset(buffer->buffers[1].head, 0,
             sizeof(struct diag_variant_buffer_head));
      buffer->buffers[1].pos += sizeof(struct diag_variant_buffer_head);
    }
  }

  return len;
}

asmlinkage int diag_variant_buffer_seal(struct diag_variant_buffer *buffer) {
  int idx = !!buffer->buffer_toggle;
  void *rbound = buffer->buffers[idx].data + buffer->buf_size;

  if (!buffer->alloced)
    return -EINVAL;
  if ((void *)buffer->buffers[idx].head < (void *)buffer->buffers[idx].data)
    return -EINVAL;
  if ((void *)buffer->buffers[idx].head >
      (rbound - sizeof(struct diag_variant_buffer_head)))
    return -EINVAL;

  buffer->buffers[idx].head->magic = DIAG_VARIANT_BUFFER_HEAD_MAGIC_SEALED;
  buffer->buffers[idx].head->len = (void *)buffer->buffers[idx].data +
                                   buffer->buffers[idx].pos -
                                   (void *)buffer->buffers[idx].head;

  return 0;
}

asmlinkage int
diag_variant_buffer_write_nolock(struct diag_variant_buffer *buffer,
                                 const void *data, size_t len) {
  unsigned int left;
  int idx = !!buffer->buffer_toggle;

  if (!buffer->alloced)
    return -EINVAL;

  left = buffer->buf_size - buffer->buffers[idx].pos;
  if (len < left) {
    memcpy(buffer->buffers[idx].data + buffer->buffers[idx].pos, data, len);
    buffer->buffers[idx].pos += len;
  }

  return len;
}

void diag_variant_buffer_mutex_lock(struct diag_variant_buffer *buffer) {
  mutex_lock(&buffer->mutex);
}

void diag_variant_buffer_mutex_unlock(struct diag_variant_buffer *buffer) {
  mutex_unlock(&buffer->mutex);
}

int copy_to_user_variant_buffer(struct diag_variant_buffer *variant_buffer,
                                void __user *ptr_len, void __user *buf,
                                size_t size) {
  size_t len;
  int ret;

  backup_diag_variant_buffer(variant_buffer);
  len = variant_buffer->product.len;
  if (size < len)
    len = size;
  ret = copy_to_user(buf, variant_buffer->product.data, len);
  if (!ret)
    ret = len;
  if (ret >= 0) {
    ret = copy_to_user(ptr_len, &ret, sizeof(int));
  }

  return ret;
}