// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Information interface for ALSA driver
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/init.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/info.h>
#include <linux/utsname.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>

int snd_info_check_reserved_words(const char *str)
{
        static const char * const reserved[] =
        {
                "version",
                "meminfo",
                "memdebug",
                "detect",
                "devices",
                "oss",
                "cards",
                "timers",
                "synth",
                "pcm",
                "seq",
                NULL
        };
        const char * const *xstr = reserved;

        while (*xstr) {
                if (!strcmp(*xstr, str))
                        return 0;
                xstr++;
        }
        if (!strncmp(str, "card", 4))
                return 0;
        return 1;
}

static DEFINE_MUTEX(info_mutex);

struct snd_info_private_data {
        struct snd_info_buffer *rbuffer;
        struct snd_info_buffer *wbuffer;
        struct snd_info_entry *entry;
        void *file_private_data;
};

static int snd_info_version_init(void);
static void snd_info_clear_entries(struct snd_info_entry *entry);

/*

 */

static struct snd_info_entry *snd_proc_root;
struct snd_info_entry *snd_seq_root;
EXPORT_SYMBOL(snd_seq_root);

#ifdef CONFIG_SND_OSSEMUL
struct snd_info_entry *snd_oss_root;
#endif

static int alloc_info_private(struct snd_info_entry *entry,
                              struct snd_info_private_data **ret)
{
        struct snd_info_private_data *data;

        if (!entry || !entry->p)
                return -ENODEV;
        if (!try_module_get(entry->module))
                return -EFAULT;
        data = kzalloc_obj(*data);
        if (!data) {
                module_put(entry->module);
                return -ENOMEM;
        }
        data->entry = entry;
        *ret = data;
        return 0;
}

static bool valid_pos(loff_t pos, size_t count)
{
        if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
                return false;
        if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
                return false;
        return true;
}

/*
 * file ops for binary proc files
 */
static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
{
        struct snd_info_private_data *data;
        struct snd_info_entry *entry;
        loff_t size;

        data = file->private_data;
        entry = data->entry;
        guard(mutex)(&entry->access);
        if (entry->c.ops->llseek)
                return entry->c.ops->llseek(entry,
                                            data->file_private_data,
                                            file, offset, orig);

        size = entry->size;
        switch (orig) {
        case SEEK_SET:
                break;
        case SEEK_CUR:
                offset += file->f_pos;
                break;
        case SEEK_END:
                if (!size)
                        return -EINVAL;
                offset += size;
                break;
        default:
                return -EINVAL;
        }
        if (offset < 0)
                return -EINVAL;
        if (size && offset > size)
                offset = size;
        file->f_pos = offset;
        return offset;
}

static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
                                   size_t count, loff_t * offset)
{
        struct snd_info_private_data *data = file->private_data;
        struct snd_info_entry *entry = data->entry;
        size_t size;
        loff_t pos;

        pos = *offset;
        if (!valid_pos(pos, count))
                return -EIO;
        if (pos >= entry->size)
                return 0;
        size = entry->size - pos;
        size = min(count, size);
        size = entry->c.ops->read(entry, data->file_private_data,
                                  file, buffer, size, pos);
        if ((ssize_t) size > 0)
                *offset = pos + size;
        return size;
}

static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
                                    size_t count, loff_t * offset)
{
        struct snd_info_private_data *data = file->private_data;
        struct snd_info_entry *entry = data->entry;
        ssize_t size = 0;
        loff_t pos;

        pos = *offset;
        if (!valid_pos(pos, count))
                return -EIO;
        if (count > 0) {
                size_t maxsize = entry->size - pos;
                count = min(count, maxsize);
                size = entry->c.ops->write(entry, data->file_private_data,
                                           file, buffer, count, pos);
        }
        if (size > 0)
                *offset = pos + size;
        return size;
}

static __poll_t snd_info_entry_poll(struct file *file, poll_table *wait)
{
        struct snd_info_private_data *data = file->private_data;
        struct snd_info_entry *entry = data->entry;
        __poll_t mask = 0;

        if (entry->c.ops->poll)
                return entry->c.ops->poll(entry,
                                          data->file_private_data,
                                          file, wait);
        if (entry->c.ops->read)
                mask |= EPOLLIN | EPOLLRDNORM;
        if (entry->c.ops->write)
                mask |= EPOLLOUT | EPOLLWRNORM;
        return mask;
}

static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
                                unsigned long arg)
{
        struct snd_info_private_data *data = file->private_data;
        struct snd_info_entry *entry = data->entry;

        if (!entry->c.ops->ioctl)
                return -ENOTTY;
        return entry->c.ops->ioctl(entry, data->file_private_data,
                                   file, cmd, arg);
}

static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct inode *inode = file_inode(file);
        struct snd_info_private_data *data;
        struct snd_info_entry *entry;

        data = file->private_data;
        if (data == NULL)
                return 0;
        entry = data->entry;
        if (!entry->c.ops->mmap)
                return -ENXIO;
        return entry->c.ops->mmap(entry, data->file_private_data,
                                  inode, file, vma);
}

static int snd_info_entry_open(struct inode *inode, struct file *file)
{
        struct snd_info_entry *entry = pde_data(inode);
        struct snd_info_private_data *data;
        int mode, err;

        guard(mutex)(&info_mutex);
        err = alloc_info_private(entry, &data);
        if (err < 0)
                return err;

        mode = file->f_flags & O_ACCMODE;
        if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
            ((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
                err = -ENODEV;
                goto error;
        }

        if (entry->c.ops->open) {
                err = entry->c.ops->open(entry, mode, &data->file_private_data);
                if (err < 0)
                        goto error;
        }

        file->private_data = data;
        return 0;

 error:
        kfree(data);
        module_put(entry->module);
        return err;
}

static int snd_info_entry_release(struct inode *inode, struct file *file)
{
        struct snd_info_private_data *data = file->private_data;
        struct snd_info_entry *entry = data->entry;

        if (entry->c.ops->release)
                entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
                                      data->file_private_data);
        module_put(entry->module);
        kfree(data);
        return 0;
}

static const struct proc_ops snd_info_entry_operations =
{
        .proc_lseek     = snd_info_entry_llseek,
        .proc_read      = snd_info_entry_read,
        .proc_write     = snd_info_entry_write,
        .proc_poll      = snd_info_entry_poll,
        .proc_ioctl     = snd_info_entry_ioctl,
        .proc_mmap      = snd_info_entry_mmap,
        .proc_open      = snd_info_entry_open,
        .proc_release   = snd_info_entry_release,
};

/*
 * file ops for text proc files
 */
static ssize_t snd_info_text_entry_write(struct file *file,
                                         const char __user *buffer,
                                         size_t count, loff_t *offset)
{
        struct seq_file *m = file->private_data;
        struct snd_info_private_data *data = m->private;
        struct snd_info_entry *entry = data->entry;
        struct snd_info_buffer *buf;
        loff_t pos;
        size_t next;

        if (!entry->c.text.write)
                return -EIO;
        pos = *offset;
        if (!valid_pos(pos, count))
                return -EIO;
        next = pos + count;
        /* don't handle too large text inputs */
        if (next > 16 * 1024)
                return -EIO;
        guard(mutex)(&entry->access);
        buf = data->wbuffer;
        if (!buf) {
                data->wbuffer = buf = kzalloc_obj(*buf);
                if (!buf)
                        return -ENOMEM;
        }
        if (next > buf->len) {
                char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
                if (!nbuf)
                        return -ENOMEM;
                kvfree(buf->buffer);
                buf->buffer = nbuf;
                buf->len = PAGE_ALIGN(next);
        }
        if (copy_from_user(buf->buffer + pos, buffer, count))
                return -EFAULT;
        buf->size = next;
        *offset = next;
        return count;
}

static int snd_info_seq_show(struct seq_file *seq, void *p)
{
        struct snd_info_private_data *data = seq->private;
        struct snd_info_entry *entry = data->entry;

        if (!entry->c.text.read) {
                return -EIO;
        } else {
                data->rbuffer->buffer = (char *)seq; /* XXX hack! */
                entry->c.text.read(entry, data->rbuffer);
        }
        return 0;
}

static int snd_info_text_entry_open(struct inode *inode, struct file *file)
{
        struct snd_info_entry *entry = pde_data(inode);
        struct snd_info_private_data *data;
        int err;

        guard(mutex)(&info_mutex);
        err = alloc_info_private(entry, &data);
        if (err < 0)
                return err;

        data->rbuffer = kzalloc_obj(*data->rbuffer);
        if (!data->rbuffer) {
                err = -ENOMEM;
                goto error;
        }
        if (entry->size)
                err = single_open_size(file, snd_info_seq_show, data,
                                       entry->size);
        else
                err = single_open(file, snd_info_seq_show, data);
        if (err < 0)
                goto error;
        return 0;

 error:
        kfree(data->rbuffer);
        kfree(data);
        module_put(entry->module);
        return err;
}

static int snd_info_text_entry_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = file->private_data;
        struct snd_info_private_data *data = m->private;
        struct snd_info_entry *entry = data->entry;

        if (data->wbuffer && entry->c.text.write)
                entry->c.text.write(entry, data->wbuffer);

        single_release(inode, file);
        kfree(data->rbuffer);
        if (data->wbuffer) {
                kvfree(data->wbuffer->buffer);
                kfree(data->wbuffer);
        }

        module_put(entry->module);
        kfree(data);
        return 0;
}

static const struct proc_ops snd_info_text_entry_ops =
{
        .proc_open      = snd_info_text_entry_open,
        .proc_release   = snd_info_text_entry_release,
        .proc_write     = snd_info_text_entry_write,
        .proc_lseek     = seq_lseek,
        .proc_read      = seq_read,
};

static struct snd_info_entry *create_subdir(struct module *mod,
                                            const char *name)
{
        struct snd_info_entry *entry;

        entry = snd_info_create_module_entry(mod, name, NULL);
        if (!entry)
                return NULL;
        entry->mode = S_IFDIR | 0555;
        if (snd_info_register(entry) < 0) {
                snd_info_free_entry(entry);
                return NULL;
        }
        return entry;
}

static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent,
                      struct module *module);

int __init snd_info_init(void)
{
        snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
        if (!snd_proc_root)
                return -ENOMEM;
        snd_proc_root->mode = S_IFDIR | 0555;
        snd_proc_root->p = proc_mkdir("asound", NULL);
        if (!snd_proc_root->p)
                goto error;
#ifdef CONFIG_SND_OSSEMUL
        snd_oss_root = create_subdir(THIS_MODULE, "oss");
        if (!snd_oss_root)
                goto error;
#endif
#if IS_ENABLED(CONFIG_SND_SEQUENCER)
        snd_seq_root = create_subdir(THIS_MODULE, "seq");
        if (!snd_seq_root)
                goto error;
#endif
        if (snd_info_version_init() < 0 ||
            snd_minor_info_init() < 0 ||
            snd_minor_info_oss_init() < 0 ||
            snd_card_info_init() < 0 ||
            snd_info_minor_register() < 0)
                goto error;
        return 0;

 error:
        snd_info_free_entry(snd_proc_root);
        return -ENOMEM;
}

int __exit snd_info_done(void)
{
        snd_info_free_entry(snd_proc_root);
        return 0;
}

static void snd_card_id_read(struct snd_info_entry *entry,
                             struct snd_info_buffer *buffer)
{
        struct snd_card *card = entry->private_data;

        snd_iprintf(buffer, "%s\n", card->id);
}

/*
 * create a card proc file
 * called from init.c
 */
int snd_info_card_create(struct snd_card *card)
{
        char str[8];
        struct snd_info_entry *entry;

        if (snd_BUG_ON(!card))
                return -ENXIO;

        sprintf(str, "card%i", card->number);
        entry = create_subdir(card->module, str);
        if (!entry)
                return -ENOMEM;
        card->proc_root = entry;

        return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
}

/*
 * register the card proc file
 * called from init.c
 * can be called multiple times for reinitialization
 */
int snd_info_card_register(struct snd_card *card)
{
        struct proc_dir_entry *p;
        int err;

        if (snd_BUG_ON(!card))
                return -ENXIO;

        err = snd_info_register(card->proc_root);
        if (err < 0)
                return err;

        if (!strcmp(card->id, card->proc_root->name))
                return 0;

        if (card->proc_root_link)
                return 0;
        p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
        if (!p)
                return -ENOMEM;
        card->proc_root_link = p;
        return 0;
}

/*
 * called on card->id change
 */
void snd_info_card_id_change(struct snd_card *card)
{
        guard(mutex)(&info_mutex);
        if (card->proc_root_link) {
                proc_remove(card->proc_root_link);
                card->proc_root_link = NULL;
        }
        if (strcmp(card->id, card->proc_root->name))
                card->proc_root_link = proc_symlink(card->id,
                                                    snd_proc_root->p,
                                                    card->proc_root->name);
}

/*
 * de-register the card proc file
 * called from init.c
 */
void snd_info_card_disconnect(struct snd_card *card)
{
        if (!card)
                return;

        proc_remove(card->proc_root_link);
        if (card->proc_root)
                proc_remove(card->proc_root->p);

        guard(mutex)(&info_mutex);
        if (card->proc_root)
                snd_info_clear_entries(card->proc_root);
        card->proc_root_link = NULL;
        card->proc_root = NULL;
}

/*
 * release the card proc file resources
 * called from init.c
 */
int snd_info_card_free(struct snd_card *card)
{
        if (!card)
                return 0;
        snd_info_free_entry(card->proc_root);
        card->proc_root = NULL;
        return 0;
}


/**
 * snd_info_get_line - read one line from the procfs buffer
 * @buffer: the procfs buffer
 * @line: the buffer to store
 * @len: the max. buffer size
 *
 * Reads one line from the buffer and stores the string.
 *
 * Return: Zero if successful, or 1 if error or EOF.
 */
int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
{
        int c;

        if (snd_BUG_ON(!buffer))
                return 1;
        if (!buffer->buffer)
                return 1;
        if (len <= 0 || buffer->stop || buffer->error)
                return 1;
        while (!buffer->stop) {
                c = buffer->buffer[buffer->curr++];
                if (buffer->curr >= buffer->size)
                        buffer->stop = 1;
                if (c == '\n')
                        break;
                if (len > 1) {
                        len--;
                        *line++ = c;
                }
        }
        *line = '\0';
        return 0;
}
EXPORT_SYMBOL(snd_info_get_line);

/**
 * snd_info_get_str - parse a string token
 * @dest: the buffer to store the string token
 * @src: the original string
 * @len: the max. length of token - 1
 *
 * Parses the original string and copy a token to the given
 * string buffer.
 *
 * Return: The updated pointer of the original string so that
 * it can be used for the next call.
 */
const char *snd_info_get_str(char *dest, const char *src, int len)
{
        int c;

        while (*src == ' ' || *src == '\t')
                src++;
        if (*src == '"' || *src == '\'') {
                c = *src++;
                while (--len > 0 && *src && *src != c) {
                        *dest++ = *src++;
                }
                if (*src == c)
                        src++;
        } else {
                while (--len > 0 && *src && *src != ' ' && *src != '\t') {
                        *dest++ = *src++;
                }
        }
        *dest = 0;
        while (*src == ' ' || *src == '\t')
                src++;
        return src;
}
EXPORT_SYMBOL(snd_info_get_str);

/*
 * snd_info_create_entry - create an info entry
 * @name: the proc file name
 * @parent: the parent directory
 *
 * Creates an info entry with the given file name and initializes as
 * the default state.
 *
 * Usually called from other functions such as
 * snd_info_create_card_entry().
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent,
                      struct module *module)
{
        struct snd_info_entry *entry;
        entry = kzalloc_obj(*entry);
        if (entry == NULL)
                return NULL;
        entry->name = kstrdup(name, GFP_KERNEL);
        if (entry->name == NULL) {
                kfree(entry);
                return NULL;
        }
        entry->mode = S_IFREG | 0444;
        entry->content = SNDRV_INFO_CONTENT_TEXT;
        mutex_init(&entry->access);
        INIT_LIST_HEAD(&entry->children);
        INIT_LIST_HEAD(&entry->list);
        entry->parent = parent;
        entry->module = module;
        if (parent) {
                guard(mutex)(&parent->access);
                list_add_tail(&entry->list, &parent->children);
        }
        return entry;
}

/**
 * snd_info_create_module_entry - create an info entry for the given module
 * @module: the module pointer
 * @name: the file name
 * @parent: the parent directory
 *
 * Creates a new info entry and assigns it to the given module.
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
struct snd_info_entry *snd_info_create_module_entry(struct module * module,
                                               const char *name,
                                               struct snd_info_entry *parent)
{
        if (!parent)
                parent = snd_proc_root;
        return snd_info_create_entry(name, parent, module);
}
EXPORT_SYMBOL(snd_info_create_module_entry);

/**
 * snd_info_create_card_entry - create an info entry for the given card
 * @card: the card instance
 * @name: the file name
 * @parent: the parent directory
 *
 * Creates a new info entry and assigns it to the given card.
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
                                             const char *name,
                                             struct snd_info_entry * parent)
{
        if (!parent)
                parent = card->proc_root;
        return snd_info_create_entry(name, parent, card->module);
}
EXPORT_SYMBOL(snd_info_create_card_entry);

static void snd_info_clear_entries(struct snd_info_entry *entry)
{
        struct snd_info_entry *p;

        if (!entry->p)
                return;
        list_for_each_entry(p, &entry->children, list)
                snd_info_clear_entries(p);
        entry->p = NULL;
}

/**
 * snd_info_free_entry - release the info entry
 * @entry: the info entry
 *
 * Releases the info entry.
 */
void snd_info_free_entry(struct snd_info_entry * entry)
{
        struct snd_info_entry *p, *n;

        if (!entry)
                return;
        if (entry->p) {
                proc_remove(entry->p);
                guard(mutex)(&info_mutex);
                snd_info_clear_entries(entry);
        }

        /* free all children at first */
        list_for_each_entry_safe(p, n, &entry->children, list)
                snd_info_free_entry(p);

        p = entry->parent;
        if (p) {
                guard(mutex)(&p->access);
                list_del(&entry->list);
        }
        kfree(entry->name);
        if (entry->private_free)
                entry->private_free(entry);
        kfree(entry);
}
EXPORT_SYMBOL(snd_info_free_entry);

static int __snd_info_register(struct snd_info_entry *entry)
{
        struct proc_dir_entry *root, *p = NULL;

        if (snd_BUG_ON(!entry))
                return -ENXIO;
        root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
        guard(mutex)(&info_mutex);
        if (entry->p || !root)
                return 0;
        if (S_ISDIR(entry->mode)) {
                p = proc_mkdir_mode(entry->name, entry->mode, root);
                if (!p)
                        return -ENOMEM;
        } else {
                const struct proc_ops *ops;
                if (entry->content == SNDRV_INFO_CONTENT_DATA)
                        ops = &snd_info_entry_operations;
                else
                        ops = &snd_info_text_entry_ops;
                p = proc_create_data(entry->name, entry->mode, root,
                                     ops, entry);
                if (!p)
                        return -ENOMEM;
                proc_set_size(p, entry->size);
        }
        entry->p = p;
        return 0;
}

/**
 * snd_info_register - register the info entry
 * @entry: the info entry
 *
 * Registers the proc info entry.
 * The all children entries are registered recursively.
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_info_register(struct snd_info_entry *entry)
{
        struct snd_info_entry *p;
        int err;

        if (!entry->p) {
                err = __snd_info_register(entry);
                if (err < 0)
                        return err;
        }

        list_for_each_entry(p, &entry->children, list) {
                err = snd_info_register(p);
                if (err < 0)
                        return err;
        }

        return 0;
}
EXPORT_SYMBOL(snd_info_register);

/**
 * snd_card_rw_proc_new - Create a read/write text proc file entry for the card
 * @card: the card instance
 * @name: the file name
 * @private_data: the arbitrary private data
 * @read: the read callback
 * @write: the write callback, NULL for read-only
 *
 * This proc file entry will be registered via snd_card_register() call, and
 * it will be removed automatically at the card removal, too.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_card_rw_proc_new(struct snd_card *card, const char *name,
                         void *private_data,
                         void (*read)(struct snd_info_entry *,
                                      struct snd_info_buffer *),
                         void (*write)(struct snd_info_entry *entry,
                                       struct snd_info_buffer *buffer))
{
        struct snd_info_entry *entry;

        entry = snd_info_create_card_entry(card, name, card->proc_root);
        if (!entry)
                return -ENOMEM;
        snd_info_set_text_ops(entry, private_data, read);
        if (write) {
                entry->mode |= 0200;
                entry->c.text.write = write;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(snd_card_rw_proc_new);

/*

 */

static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
        snd_iprintf(buffer,
                    "Advanced Linux Sound Architecture Driver Version k%s.\n",
                    init_utsname()->release);
}

static int __init snd_info_version_init(void)
{
        struct snd_info_entry *entry;

        entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
        if (entry == NULL)
                return -ENOMEM;
        entry->c.text.read = snd_info_version_read;
        return snd_info_register(entry); /* freed in error path */
}