#include <linux/mm.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include "internal.h"

/*
 * Logic: we've got two memory sums for each process, "shared", and
 * "non-shared". Shared memory may get counted more then once, for
 * each process that owns it. Non-shared memory is counted
 * accurately.
 */
char *task_mem(struct mm_struct *mm, char *buffer)
{
        struct vm_list_struct *vml;
        unsigned long bytes = 0, sbytes = 0, slack = 0;
        
        down_read(&mm->mmap_sem);
        for (vml = mm->context.vmlist; vml; vml = vml->next) {
                if (!vml->vma)
                        continue;

                bytes += kobjsize(vml);
                if (atomic_read(&mm->mm_count) > 1 ||
                    atomic_read(&vml->vma->vm_usage) > 1
                    ) {
                        sbytes += kobjsize((void *) vml->vma->vm_start);
                        sbytes += kobjsize(vml->vma);
                } else {
                        bytes += kobjsize((void *) vml->vma->vm_start);
                        bytes += kobjsize(vml->vma);
                        slack += kobjsize((void *) vml->vma->vm_start) -
                                (vml->vma->vm_end - vml->vma->vm_start);
                }
        }

        if (atomic_read(&mm->mm_count) > 1)
                sbytes += kobjsize(mm);
        else
                bytes += kobjsize(mm);
        
        if (current->fs && atomic_read(&current->fs->count) > 1)
                sbytes += kobjsize(current->fs);
        else
                bytes += kobjsize(current->fs);

        if (current->files && atomic_read(&current->files->count) > 1)
                sbytes += kobjsize(current->files);
        else
                bytes += kobjsize(current->files);

        if (current->sighand && atomic_read(&current->sighand->count) > 1)
                sbytes += kobjsize(current->sighand);
        else
                bytes += kobjsize(current->sighand);

        bytes += kobjsize(current); /* includes kernel stack */

        buffer += sprintf(buffer,
                "Mem:\t%8lu bytes\n"
                "Slack:\t%8lu bytes\n"
                "Shared:\t%8lu bytes\n",
                bytes, slack, sbytes);

        up_read(&mm->mmap_sem);
        return buffer;
}

unsigned long task_vsize(struct mm_struct *mm)
{
        struct vm_list_struct *tbp;
        unsigned long vsize = 0;

        down_read(&mm->mmap_sem);
        for (tbp = mm->context.vmlist; tbp; tbp = tbp->next) {
                if (tbp->vma)
                        vsize += kobjsize((void *) tbp->vma->vm_start);
        }
        up_read(&mm->mmap_sem);
        return vsize;
}

int task_statm(struct mm_struct *mm, int *shared, int *text,
               int *data, int *resident)
{
        struct vm_list_struct *tbp;
        int size = kobjsize(mm);

        down_read(&mm->mmap_sem);
        for (tbp = mm->context.vmlist; tbp; tbp = tbp->next) {
                size += kobjsize(tbp);
                if (tbp->vma) {
                        size += kobjsize(tbp->vma);
                        size += kobjsize((void *) tbp->vma->vm_start);
                }
        }

        size += (*text = mm->end_code - mm->start_code);
        size += (*data = mm->start_stack - mm->start_data);
        up_read(&mm->mmap_sem);
        *resident = size;
        return size;
}

int proc_exe_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
        struct vm_list_struct *vml;
        struct vm_area_struct *vma;
        struct task_struct *task = get_proc_task(inode);
        struct mm_struct *mm = get_task_mm(task);
        int result = -ENOENT;

        if (!mm)
                goto out;
        down_read(&mm->mmap_sem);

        vml = mm->context.vmlist;
        vma = NULL;
        while (vml) {
                if ((vml->vma->vm_flags & VM_EXECUTABLE) && vml->vma->vm_file) {
                        vma = vml->vma;
                        break;
                }
                vml = vml->next;
        }

        if (vma) {
                *mnt = mntget(vma->vm_file->f_path.mnt);
                *dentry = dget(vma->vm_file->f_path.dentry);
                result = 0;
        }

        up_read(&mm->mmap_sem);
        mmput(mm);
out:
        return result;
}

/*
 * display mapping lines for a particular process's /proc/pid/maps
 */
static int show_map(struct seq_file *m, void *_vml)
{
        struct vm_list_struct *vml = _vml;
        struct proc_maps_private *priv = m->private;
        struct task_struct *task = priv->task;

        if (maps_protect && !ptrace_may_attach(task))
                return -EACCES;

        return nommu_vma_show(m, vml->vma);
}

static void *m_start(struct seq_file *m, loff_t *pos)
{
        struct proc_maps_private *priv = m->private;
        struct vm_list_struct *vml;
        struct mm_struct *mm;
        loff_t n = *pos;

        /* pin the task and mm whilst we play with them */
        priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
        if (!priv->task)
                return NULL;

        mm = mm_for_maps(priv->task);
        if (!mm) {
                put_task_struct(priv->task);
                priv->task = NULL;
                return NULL;
        }

        /* start from the Nth VMA */
        for (vml = mm->context.vmlist; vml; vml = vml->next)
                if (n-- == 0)
                        return vml;
        return NULL;
}

static void m_stop(struct seq_file *m, void *_vml)
{
        struct proc_maps_private *priv = m->private;

        if (priv->task) {
                struct mm_struct *mm = priv->task->mm;
                up_read(&mm->mmap_sem);
                mmput(mm);
                put_task_struct(priv->task);
        }
}

static void *m_next(struct seq_file *m, void *_vml, loff_t *pos)
{
        struct vm_list_struct *vml = _vml;

        (*pos)++;
        return vml ? vml->next : NULL;
}

static struct seq_operations proc_pid_maps_ops = {
        .start  = m_start,
        .next   = m_next,
        .stop   = m_stop,
        .show   = show_map
};

static int maps_open(struct inode *inode, struct file *file)
{
        struct proc_maps_private *priv;
        int ret = -ENOMEM;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (priv) {
                priv->pid = proc_pid(inode);
                ret = seq_open(file, &proc_pid_maps_ops);
                if (!ret) {
                        struct seq_file *m = file->private_data;
                        m->private = priv;
                } else {
                        kfree(priv);
                }
        }
        return ret;
}

const struct file_operations proc_maps_operations = {
        .open           = maps_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release_private,
};