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Sourcecode: linux-2.6 version File versions

atags.c

#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/proc_fs.h>
#include <asm/setup.h>
#include <asm/types.h>
#include <asm/page.h>

struct buffer {
      size_t size;
      char *data;
};
static struct buffer tags_buffer;

static int
read_buffer(char* page, char** start, off_t off, int count,
      int* eof, void* data)
{
      struct buffer *buffer = (struct buffer *)data;

      if (off >= buffer->size) {
            *eof = 1;
            return 0;
      }

      count = min((int) (buffer->size - off), count);

      memcpy(page, &buffer->data[off], count);

      return count;
}


static int
create_proc_entries(void)
{
      struct proc_dir_entry* tags_entry;

      tags_entry = create_proc_read_entry("atags", 0400, NULL, read_buffer, &tags_buffer);
      if (!tags_entry)
            return -ENOMEM;

      return 0;
}


static char __initdata atags_copy_buf[KEXEC_BOOT_PARAMS_SIZE];
static char __initdata *atags_copy;

void __init save_atags(const struct tag *tags)
{
      atags_copy = atags_copy_buf;
      memcpy(atags_copy, tags, KEXEC_BOOT_PARAMS_SIZE);
}


static int __init init_atags_procfs(void)
{
      struct tag *tag;
      int error;

      if (!atags_copy) {
            printk(KERN_WARNING "Exporting ATAGs: No saved tags found\n");
            return -EIO;
      }

      for (tag = (struct tag *) atags_copy; tag->hdr.size; tag = tag_next(tag))
            ;

      tags_buffer.size = ((char *) tag - atags_copy) + sizeof(tag->hdr);
      tags_buffer.data = kmalloc(tags_buffer.size, GFP_KERNEL);
      if (tags_buffer.data == NULL)
            return -ENOMEM;
      memcpy(tags_buffer.data, atags_copy, tags_buffer.size);

      error = create_proc_entries();
      if (error) {
            printk(KERN_ERR "Exporting ATAGs: not enough memory\n");
            kfree(tags_buffer.data);
            tags_buffer.size = 0;
            tags_buffer.data = NULL;
      }

      return error;
}

arch_initcall(init_atags_procfs);

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