Add Linux native GUI program for Ventoy2Disk.

[Ventoy.git] / LinuxGUI / Ventoy2Disk / Lib / exfat / src / libexfat / node.c

/*
        node.c (09.10.09)
        exFAT file system implementation library.

        Free exFAT implementation.
        Copyright (C) 2010-2018  Andrew Nayenko

        This program is free software; you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 2 of the License, or
        (at your option) any later version.

        This program is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License along
        with this program; if not, write to the Free Software Foundation, Inc.,
        51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "exfat.h"
#include <errno.h>
#include <string.h>
#include <inttypes.h>

#define EXFAT_ENTRY_NONE (-1)

struct exfat_node* exfat_get_node(struct exfat_node* node)
{
        /* if we switch to multi-threaded mode we will need atomic
           increment here and atomic decrement in exfat_put_node() */
        node->references++;
        return node;
}

void exfat_put_node(struct exfat* ef, struct exfat_node* node)
{
        char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];

        --node->references;
        if (node->references < 0)
        {
                exfat_get_name(node, buffer);
                exfat_bug("reference counter of '%s' is below zero", buffer);
        }
        else if (node->references == 0 && node != ef->root)
        {
                if (node->is_dirty)
                {
                        exfat_get_name(node, buffer);
                        exfat_warn("dirty node '%s' with zero references", buffer);
                }
        }
}

/**
 * This function must be called on rmdir and unlink (after the last
 * exfat_put_node()) to free clusters.
 */
int exfat_cleanup_node(struct exfat* ef, struct exfat_node* node)
{
        int rc = 0;

        if (node->references != 0)
                exfat_bug("unable to cleanup a node with %d references",
                                node->references);

        if (node->is_unlinked)
        {
                /* free all clusters and node structure itself */
                rc = exfat_truncate(ef, node, 0, true);
                /* free the node even in case of error or its memory will be lost */
                free(node);
        }
        return rc;
}

static int read_entries(struct exfat* ef, struct exfat_node* dir,
                struct exfat_entry* entries, int n, off_t offset)
{
        ssize_t size;

        if (!(dir->attrib & EXFAT_ATTRIB_DIR))
                exfat_bug("attempted to read entries from a file");

        size = exfat_generic_pread(ef, dir, entries,
                        sizeof(struct exfat_entry[n]), offset);
        if (size == sizeof(struct exfat_entry[n]))
                return 0; /* success */
        if (size == 0)
                return -ENOENT;
        if (size < 0)
                return -EIO;
        exfat_error("read %zd bytes instead of %zu bytes", size,
                        sizeof(struct exfat_entry[n]));
        return -EIO;
}

static int write_entries(struct exfat* ef, struct exfat_node* dir,
                const struct exfat_entry* entries, int n, off_t offset)
{
        ssize_t size;

        if (!(dir->attrib & EXFAT_ATTRIB_DIR))
                exfat_bug("attempted to write entries into a file");

        size = exfat_generic_pwrite(ef, dir, entries,
                        sizeof(struct exfat_entry[n]), offset);
        if (size == sizeof(struct exfat_entry[n]))
                return 0; /* success */
        if (size < 0)
                return -EIO;
        exfat_error("wrote %zd bytes instead of %zu bytes", size,
                        sizeof(struct exfat_entry[n]));
        return -EIO;
}

static struct exfat_node* allocate_node(void)
{
        struct exfat_node* node = malloc(sizeof(struct exfat_node));
        if (node == NULL)
        {
                exfat_error("failed to allocate node");
                return NULL;
        }
        memset(node, 0, sizeof(struct exfat_node));
        return node;
}

static void init_node_meta1(struct exfat_node* node,
                const struct exfat_entry_meta1* meta1)
{
        node->attrib = le16_to_cpu(meta1->attrib);
        node->continuations = meta1->continuations;
        node->mtime = exfat_exfat2unix(meta1->mdate, meta1->mtime,
                        meta1->mtime_cs);
        /* there is no centiseconds field for atime */
        node->atime = exfat_exfat2unix(meta1->adate, meta1->atime, 0);
}

static void init_node_meta2(struct exfat_node* node,
                const struct exfat_entry_meta2* meta2)
{
        node->size = le64_to_cpu(meta2->size);
        node->start_cluster = le32_to_cpu(meta2->start_cluster);
        node->fptr_cluster = node->start_cluster;
        node->is_contiguous = ((meta2->flags & EXFAT_FLAG_CONTIGUOUS) != 0);
}

static void init_node_name(struct exfat_node* node,
                const struct exfat_entry* entries, int n)
{
        int i;

        for (i = 0; i < n; i++)
                memcpy(node->name + i * EXFAT_ENAME_MAX,
                                ((const struct exfat_entry_name*) &entries[i])->name,
                                EXFAT_ENAME_MAX * sizeof(le16_t));
}

static bool check_entries(const struct exfat_entry* entry, int n)
{
        int previous = EXFAT_ENTRY_NONE;
        int current;
        int i;

        /* check transitions between entries types */
        for (i = 0; i < n + 1; previous = current, i++)
        {
                bool valid = false;

                current = (i < n) ? entry[i].type : EXFAT_ENTRY_NONE;
                switch (previous)
                {
                case EXFAT_ENTRY_NONE:
                        valid = (current == EXFAT_ENTRY_FILE);
                        break;
                case EXFAT_ENTRY_FILE:
                        valid = (current == EXFAT_ENTRY_FILE_INFO);
                        break;
                case EXFAT_ENTRY_FILE_INFO:
                        valid = (current == EXFAT_ENTRY_FILE_NAME);
                        break;
                case EXFAT_ENTRY_FILE_NAME:
                        valid = (current == EXFAT_ENTRY_FILE_NAME ||
                                 current == EXFAT_ENTRY_NONE ||
                                 current >= EXFAT_ENTRY_FILE_TAIL);
                        break;
                case EXFAT_ENTRY_FILE_TAIL ... 0xff:
                        valid = (current >= EXFAT_ENTRY_FILE_TAIL ||
                                 current == EXFAT_ENTRY_NONE);
                        break;
                }

                if (!valid)
                {
                        exfat_error("unexpected entry type %#x after %#x at %d/%d",
                                        current, previous, i, n);
                        return false;
                }
        }
        return true;
}

static bool check_node(const struct exfat* ef, struct exfat_node* node,
                le16_t actual_checksum, const struct exfat_entry_meta1* meta1,
                const struct exfat_entry_meta2* meta2)
{
        int cluster_size = CLUSTER_SIZE(*ef->sb);
        uint64_t clusters_heap_size =
                        (uint64_t) le32_to_cpu(ef->sb->cluster_count) * cluster_size;
        char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
        bool ret = true;

        /*
           Validate checksum first. If it's invalid all other fields probably
           contain just garbage.
        */
        if (le16_to_cpu(actual_checksum) != le16_to_cpu(meta1->checksum))
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' has invalid checksum (%#hx != %#hx)", buffer,
                                le16_to_cpu(actual_checksum), le16_to_cpu(meta1->checksum));
                if (!EXFAT_REPAIR(invalid_node_checksum, ef, node))
                        ret = false;
        }

        /*
           exFAT does not support sparse files but allows files with uninitialized
           clusters. For such files valid_size means initialized data size and
           cannot be greater than file size. See SetFileValidData() function
           description in MSDN.
        */
        if (le64_to_cpu(meta2->valid_size) > node->size)
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' has valid size (%"PRIu64") greater than size "
                                "(%"PRIu64")", buffer, le64_to_cpu(meta2->valid_size),
                                node->size);
                ret = false;
        }

        /*
           Empty file must have zero start cluster. Non-empty file must start
           with a valid cluster. Directories cannot be empty (i.e. must always
           have a valid start cluster), but we will check this later while
           reading that directory to give user a chance to read this directory.
        */
        if (node->size == 0 && node->start_cluster != EXFAT_CLUSTER_FREE)
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' is empty but start cluster is %#x", buffer,
                                node->start_cluster);
                ret = false;
        }
        if (node->size > 0 && CLUSTER_INVALID(*ef->sb, node->start_cluster))
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' points to invalid cluster %#x", buffer,
                                node->start_cluster);
                ret = false;
        }

        /* File or directory cannot be larger than clusters heap. */
        if (node->size > clusters_heap_size)
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' is larger than clusters heap: %"PRIu64" > %"PRIu64,
                                buffer, node->size, clusters_heap_size);
                ret = false;
        }

        /* Empty file or directory must be marked as non-contiguous. */
        if (node->size == 0 && node->is_contiguous)
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' is empty but marked as contiguous (%#hx)", buffer,
                                node->attrib);
                ret = false;
        }

        /* Directory size must be aligned on at cluster boundary. */
        if ((node->attrib & EXFAT_ATTRIB_DIR) && node->size % cluster_size != 0)
        {
                exfat_get_name(node, buffer);
                exfat_error("'%s' directory size %"PRIu64" is not divisible by %d", buffer,
                                node->size, cluster_size);
                ret = false;
        }

        return ret;
}

static int parse_file_entries(struct exfat* ef, struct exfat_node* node,
                const struct exfat_entry* entries, int n)
{
        const struct exfat_entry_meta1* meta1;
        const struct exfat_entry_meta2* meta2;
        int mandatory_entries;

        if (!check_entries(entries, n))
                return -EIO;

        meta1 = (const struct exfat_entry_meta1*) &entries[0];
        if (meta1->continuations < 2)
        {
                exfat_error("too few continuations (%hhu)", meta1->continuations);
                return -EIO;
        }
        meta2 = (const struct exfat_entry_meta2*) &entries[1];
        if (meta2->flags & ~(EXFAT_FLAG_ALWAYS1 | EXFAT_FLAG_CONTIGUOUS))
        {
                exfat_error("unknown flags in meta2 (%#hhx)", meta2->flags);
                return -EIO;
        }
        mandatory_entries = 2 + DIV_ROUND_UP(meta2->name_length, EXFAT_ENAME_MAX);
        if (meta1->continuations < mandatory_entries - 1)
        {
                exfat_error("too few continuations (%hhu < %d)",
                                meta1->continuations, mandatory_entries - 1);
                return -EIO;
        }

        init_node_meta1(node, meta1);
        init_node_meta2(node, meta2);
        init_node_name(node, entries + 2, mandatory_entries - 2);

        if (!check_node(ef, node, exfat_calc_checksum(entries, n), meta1, meta2))
                return -EIO;

        return 0;
}

static int parse_file_entry(struct exfat* ef, struct exfat_node* parent,
                struct exfat_node** node, off_t* offset, int n)
{
        struct exfat_entry entries[n];
        int rc;

        rc = read_entries(ef, parent, entries, n, *offset);
        if (rc != 0)
                return rc;

        /* a new node has zero references */
        *node = allocate_node();
        if (*node == NULL)
                return -ENOMEM;
        (*node)->entry_offset = *offset;

        rc = parse_file_entries(ef, *node, entries, n);
        if (rc != 0)
        {
                free(*node);
                return rc;
        }

        *offset += sizeof(struct exfat_entry[n]);
        return 0;
}

static void decompress_upcase(uint16_t* output, const le16_t* source,
                size_t size)
{
        size_t si;
        size_t oi;

        for (oi = 0; oi < EXFAT_UPCASE_CHARS; oi++)
                output[oi] = oi;

        for (si = 0, oi = 0; si < size && oi < EXFAT_UPCASE_CHARS; si++)
        {
                uint16_t ch = le16_to_cpu(source[si]);

                if (ch == 0xffff && si + 1 < size)      /* indicates a run */
                        oi += le16_to_cpu(source[++si]);
                else
                        output[oi++] = ch;
        }
}

/*
 * Read one entry in a directory at offset position and build a new node
 * structure.
 */
static int readdir(struct exfat* ef, struct exfat_node* parent,
                struct exfat_node** node, off_t* offset)
{
        int rc;
        struct exfat_entry entry;
        const struct exfat_entry_meta1* meta1;
        const struct exfat_entry_upcase* upcase;
        const struct exfat_entry_bitmap* bitmap;
        const struct exfat_entry_label* label;
        uint64_t upcase_size = 0;
        le16_t* upcase_comp = NULL;

        for (;;)
        {
                rc = read_entries(ef, parent, &entry, 1, *offset);
                if (rc != 0)
                        return rc;

                switch (entry.type)
                {
                case EXFAT_ENTRY_FILE:
                        meta1 = (const struct exfat_entry_meta1*) &entry;
                        return parse_file_entry(ef, parent, node, offset,
                                        1 + meta1->continuations);

                case EXFAT_ENTRY_UPCASE:
                        if (ef->upcase != NULL)
                                break;
                        upcase = (const struct exfat_entry_upcase*) &entry;
                        if (CLUSTER_INVALID(*ef->sb, le32_to_cpu(upcase->start_cluster)))
                        {
                                exfat_error("invalid cluster 0x%x in upcase table",
                                                le32_to_cpu(upcase->start_cluster));
                                return -EIO;
                        }
                        upcase_size = le64_to_cpu(upcase->size);
                        if (upcase_size == 0 ||
                                upcase_size > EXFAT_UPCASE_CHARS * sizeof(uint16_t) ||
                                upcase_size % sizeof(uint16_t) != 0)
                        {
                                exfat_error("bad upcase table size (%"PRIu64" bytes)",
                                                upcase_size);
                                return -EIO;
                        }
                        upcase_comp = malloc(upcase_size);
                        if (upcase_comp == NULL)
                        {
                                exfat_error("failed to allocate upcase table (%"PRIu64" bytes)",
                                                upcase_size);
                                return -ENOMEM;
                        }

                        /* read compressed upcase table */
                        if (exfat_pread(ef->dev, upcase_comp, upcase_size,
                                        exfat_c2o(ef, le32_to_cpu(upcase->start_cluster))) < 0)
                        {
                                free(upcase_comp);
                                exfat_error("failed to read upper case table "
                                                "(%"PRIu64" bytes starting at cluster %#x)",
                                                upcase_size,
                                                le32_to_cpu(upcase->start_cluster));
                                return -EIO;
                        }

                        /* decompress upcase table */
                        ef->upcase = calloc(EXFAT_UPCASE_CHARS, sizeof(uint16_t));
                        if (ef->upcase == NULL)
                        {
                                free(upcase_comp);
                                exfat_error("failed to allocate decompressed upcase table");
                                return -ENOMEM;
                        }
                        decompress_upcase(ef->upcase, upcase_comp,
                                        upcase_size / sizeof(uint16_t));
                        free(upcase_comp);
                        break;

                case EXFAT_ENTRY_BITMAP:
                        bitmap = (const struct exfat_entry_bitmap*) &entry;
                        ef->cmap.start_cluster = le32_to_cpu(bitmap->start_cluster);
                        if (CLUSTER_INVALID(*ef->sb, ef->cmap.start_cluster))
                        {
                                exfat_error("invalid cluster 0x%x in clusters bitmap",
                                                ef->cmap.start_cluster);
                                return -EIO;
                        }
                        ef->cmap.size = le32_to_cpu(ef->sb->cluster_count);
                        if (le64_to_cpu(bitmap->size) < DIV_ROUND_UP(ef->cmap.size, 8))
                        {
                                exfat_error("invalid clusters bitmap size: %"PRIu64
                                                " (expected at least %u)",
                                                le64_to_cpu(bitmap->size),
                                                DIV_ROUND_UP(ef->cmap.size, 8));
                                return -EIO;
                        }
                        /* FIXME bitmap can be rather big, up to 512 MB */
                        ef->cmap.chunk_size = ef->cmap.size;
                        ef->cmap.chunk = malloc(BMAP_SIZE(ef->cmap.chunk_size));
                        if (ef->cmap.chunk == NULL)
                        {
                                exfat_error("failed to allocate clusters bitmap chunk "
                                                "(%"PRIu64" bytes)", le64_to_cpu(bitmap->size));
                                return -ENOMEM;
                        }

                        if (exfat_pread(ef->dev, ef->cmap.chunk,
                                        BMAP_SIZE(ef->cmap.chunk_size),
                                        exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
                        {
                                exfat_error("failed to read clusters bitmap "
                                                "(%"PRIu64" bytes starting at cluster %#x)",
                                                le64_to_cpu(bitmap->size), ef->cmap.start_cluster);
                                return -EIO;
                        }
                        break;

                case EXFAT_ENTRY_LABEL:
                        label = (const struct exfat_entry_label*) &entry;
                        if (label->length > EXFAT_ENAME_MAX)
                        {
                                exfat_error("too long label (%hhu chars)", label->length);
                                return -EIO;
                        }
                        if (utf16_to_utf8(ef->label, label->name,
                                                sizeof(ef->label), EXFAT_ENAME_MAX) != 0)
                                return -EIO;
                        break;

                default:
                        if (!(entry.type & EXFAT_ENTRY_VALID))
                                break; /* deleted entry, ignore it */

                        exfat_error("unknown entry type %#hhx", entry.type);
                        if (!EXFAT_REPAIR(unknown_entry, ef, parent, &entry, *offset))
                                return -EIO;
                }
                *offset += sizeof(entry);
        }
        /* we never reach here */
}

int exfat_cache_directory(struct exfat* ef, struct exfat_node* dir)
{
        off_t offset = 0;
        int rc;
        struct exfat_node* node;
        struct exfat_node* current = NULL;

        if (dir->is_cached)
                return 0; /* already cached */

        while ((rc = readdir(ef, dir, &node, &offset)) == 0)
        {
                node->parent = dir;
                if (current != NULL)
                {
                        current->next = node;
                        node->prev = current;
                }
                else
                        dir->child = node;

                current = node;
        }

        if (rc != -ENOENT)
        {
                /* rollback */
                for (current = dir->child; current; current = node)
                {
                        node = current->next;
                        free(current);
                }
                dir->child = NULL;
                return rc;
        }

        dir->is_cached = true;
        return 0;
}

static void tree_attach(struct exfat_node* dir, struct exfat_node* node)
{
        node->parent = dir;
        if (dir->child)
        {
                dir->child->prev = node;
                node->next = dir->child;
        }
        dir->child = node;
}

static void tree_detach(struct exfat_node* node)
{
        if (node->prev)
                node->prev->next = node->next;
        else /* this is the first node in the list */
                node->parent->child = node->next;
        if (node->next)
                node->next->prev = node->prev;
        node->parent = NULL;
        node->prev = NULL;
        node->next = NULL;
}

static void reset_cache(struct exfat* ef, struct exfat_node* node)
{
        char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];

        while (node->child)
        {
                struct exfat_node* p = node->child;
                reset_cache(ef, p);
                tree_detach(p);
                free(p);
        }
        node->is_cached = false;
        if (node->references != 0)
        {
                exfat_get_name(node, buffer);
                exfat_warn("non-zero reference counter (%d) for '%s'",
                                node->references, buffer);
        }
        if (node != ef->root && node->is_dirty)
        {
                exfat_get_name(node, buffer);
                exfat_bug("node '%s' is dirty", buffer);
        }
        while (node->references)
                exfat_put_node(ef, node);
}

void exfat_reset_cache(struct exfat* ef)
{
        reset_cache(ef, ef->root);
}

int exfat_flush_node(struct exfat* ef, struct exfat_node* node)
{
        struct exfat_entry entries[1 + node->continuations];
        struct exfat_entry_meta1* meta1 = (struct exfat_entry_meta1*) &entries[0];
        struct exfat_entry_meta2* meta2 = (struct exfat_entry_meta2*) &entries[1];
        int rc;

        if (!node->is_dirty)
                return 0; /* no need to flush */

        if (ef->ro)
                exfat_bug("unable to flush node to read-only FS");

        if (node->parent == NULL)
                return 0; /* do not flush unlinked node */

        rc = read_entries(ef, node->parent, entries, 1 + node->continuations,
                        node->entry_offset);
        if (rc != 0)
                return rc;
        if (!check_entries(entries, 1 + node->continuations))
                return -EIO;

        meta1->attrib = cpu_to_le16(node->attrib);
        exfat_unix2exfat(node->mtime, &meta1->mdate, &meta1->mtime,
                        &meta1->mtime_cs);
        exfat_unix2exfat(node->atime, &meta1->adate, &meta1->atime, NULL);
        meta2->size = meta2->valid_size = cpu_to_le64(node->size);
        meta2->start_cluster = cpu_to_le32(node->start_cluster);
        meta2->flags = EXFAT_FLAG_ALWAYS1;
        /* empty files must not be marked as contiguous */
        if (node->size != 0 && node->is_contiguous)
                meta2->flags |= EXFAT_FLAG_CONTIGUOUS;
        /* name hash remains unchanged, no need to recalculate it */

        meta1->checksum = exfat_calc_checksum(entries, 1 + node->continuations);
        rc = write_entries(ef, node->parent, entries, 1 + node->continuations,
                        node->entry_offset);
        if (rc != 0)
                return rc;

        node->is_dirty = false;
        return exfat_flush(ef);
}

static int erase_entries(struct exfat* ef, struct exfat_node* dir, int n,
                off_t offset)
{
        struct exfat_entry entries[n];
        int rc;
        int i;

        rc = read_entries(ef, dir, entries, n, offset);
        if (rc != 0)
                return rc;
        for (i = 0; i < n; i++)
                entries[i].type &= ~EXFAT_ENTRY_VALID;
        return write_entries(ef, dir, entries, n, offset);
}

static int erase_node(struct exfat* ef, struct exfat_node* node)
{
        int rc;

        exfat_get_node(node->parent);
        rc = erase_entries(ef, node->parent, 1 + node->continuations,
                        node->entry_offset);
        if (rc != 0)
        {
                exfat_put_node(ef, node->parent);
                return rc;
        }
        rc = exfat_flush_node(ef, node->parent);
        exfat_put_node(ef, node->parent);
        return rc;
}

static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
                off_t deleted_offset)
{
        const struct exfat_node* node;
        const struct exfat_node* last_node;
        uint64_t entries = 0;
        uint64_t new_size;

        if (!(dir->attrib & EXFAT_ATTRIB_DIR))
                exfat_bug("attempted to shrink a file");
        if (!dir->is_cached)
                exfat_bug("attempted to shrink uncached directory");

        for (last_node = node = dir->child; node; node = node->next)
        {
                if (deleted_offset < node->entry_offset)
                {
                        /* there are other entries after the removed one, no way to shrink
                           this directory */
                        return 0;
                }
                if (last_node->entry_offset < node->entry_offset)
                        last_node = node;
        }

        if (last_node)
        {
                /* offset of the last entry */
                entries += last_node->entry_offset / sizeof(struct exfat_entry);
                /* two subentries with meta info */
                entries += 2;
                /* subentries with file name */
                entries += DIV_ROUND_UP(utf16_length(last_node->name),
                                EXFAT_ENAME_MAX);
        }

        new_size = DIV_ROUND_UP(entries * sizeof(struct exfat_entry),
                                 CLUSTER_SIZE(*ef->sb)) * CLUSTER_SIZE(*ef->sb);
        if (new_size == 0) /* directory always has at least 1 cluster */
                new_size = CLUSTER_SIZE(*ef->sb);
        if (new_size == dir->size)
                return 0;
        return exfat_truncate(ef, dir, new_size, true);
}

static int delete(struct exfat* ef, struct exfat_node* node)
{
        struct exfat_node* parent = node->parent;
        off_t deleted_offset = node->entry_offset;
        int rc;

        exfat_get_node(parent);
        rc = erase_node(ef, node);
        if (rc != 0)
        {
                exfat_put_node(ef, parent);
                return rc;
        }
        tree_detach(node);
        rc = shrink_directory(ef, parent, deleted_offset);
        node->is_unlinked = true;
        if (rc != 0)
        {
                exfat_flush_node(ef, parent);
                exfat_put_node(ef, parent);
                return rc;
        }
        exfat_update_mtime(parent);
        rc = exfat_flush_node(ef, parent);
        exfat_put_node(ef, parent);
        return rc;
}

int exfat_unlink(struct exfat* ef, struct exfat_node* node)
{
        if (node->attrib & EXFAT_ATTRIB_DIR)
                return -EISDIR;
        return delete(ef, node);
}

int exfat_rmdir(struct exfat* ef, struct exfat_node* node)
{
        int rc;

        if (!(node->attrib & EXFAT_ATTRIB_DIR))
                return -ENOTDIR;
        /* check that directory is empty */
        rc = exfat_cache_directory(ef, node);
        if (rc != 0)
                return rc;
        if (node->child)
                return -ENOTEMPTY;
        return delete(ef, node);
}

static int check_slot(struct exfat* ef, struct exfat_node* dir, off_t offset,
                int n)
{
        struct exfat_entry entries[n];
        int rc;
        size_t i;

        /* Root directory contains entries, that don't have any nodes associated
           with them (clusters bitmap, upper case table, label). We need to be
           careful not to overwrite them. */
        if (dir != ef->root)
                return 0;

        rc = read_entries(ef, dir, entries, n, offset);
        if (rc != 0)
                return rc;
        for (i = 0; i < n; i++)
                if (entries[i].type & EXFAT_ENTRY_VALID)
                        return -EINVAL;
        return 0;
}

static int find_slot(struct exfat* ef, struct exfat_node* dir,
                off_t* offset, int n)
{
        bitmap_t* dmap;
        struct exfat_node* p;
        size_t i;
        int contiguous = 0;

        if (!dir->is_cached)
                exfat_bug("directory is not cached");

        /* build a bitmap of valid entries in the directory */
        dmap = calloc(BMAP_SIZE(dir->size / sizeof(struct exfat_entry)),
                        sizeof(bitmap_t));
        if (dmap == NULL)
        {
                exfat_error("failed to allocate directory bitmap (%"PRIu64")",
                                dir->size / sizeof(struct exfat_entry));
                return -ENOMEM;
        }
        for (p = dir->child; p != NULL; p = p->next)
                for (i = 0; i < 1 + p->continuations; i++)
                        BMAP_SET(dmap, p->entry_offset / sizeof(struct exfat_entry) + i);

        /* find a slot in the directory entries bitmap */
        for (i = 0; i < dir->size / sizeof(struct exfat_entry); i++)
        {
                if (BMAP_GET(dmap, i) == 0)
                {
                        if (contiguous++ == 0)
                                *offset = (off_t) i * sizeof(struct exfat_entry);
                        if (contiguous == n)
                                /* suitable slot is found, check that it's not occupied */
                                switch (check_slot(ef, dir, *offset, n))
                                {
                                case 0:
                                        free(dmap);
                                        return 0;
                                case -EIO:
                                        free(dmap);
                                        return -EIO;
                                case -EINVAL:
                                        /* slot at (i-n) is occupied, go back and check (i-n+1) */
                                        i -= contiguous - 1;
                                        contiguous = 0;
                                        break;
                                }
                }
                else
                        contiguous = 0;
        }
        free(dmap);

        /* no suitable slots found, extend the directory */
        if (contiguous == 0)
                *offset = dir->size;
        return exfat_truncate(ef, dir,
                        ROUND_UP(dir->size + sizeof(struct exfat_entry[n - contiguous]),
                                        CLUSTER_SIZE(*ef->sb)),
                        true);
}

static int commit_entry(struct exfat* ef, struct exfat_node* dir,
                const le16_t* name, off_t offset, uint16_t attrib)
{
        struct exfat_node* node;
        const size_t name_length = utf16_length(name);
        const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
        struct exfat_entry entries[2 + name_entries];
        struct exfat_entry_meta1* meta1 = (struct exfat_entry_meta1*) &entries[0];
        struct exfat_entry_meta2* meta2 = (struct exfat_entry_meta2*) &entries[1];
        int i;
        int rc;

        memset(entries, 0, sizeof(struct exfat_entry[2]));

        meta1->type = EXFAT_ENTRY_FILE;
        meta1->continuations = 1 + name_entries;
        meta1->attrib = cpu_to_le16(attrib);
        exfat_unix2exfat(time(NULL), &meta1->crdate, &meta1->crtime,
                        &meta1->crtime_cs);
        meta1->adate = meta1->mdate = meta1->crdate;
        meta1->atime = meta1->mtime = meta1->crtime;
        meta1->mtime_cs = meta1->crtime_cs; /* there is no atime_cs */

        meta2->type = EXFAT_ENTRY_FILE_INFO;
        meta2->flags = EXFAT_FLAG_ALWAYS1;
        meta2->name_length = name_length;
        meta2->name_hash = exfat_calc_name_hash(ef, name, name_length);
        meta2->start_cluster = cpu_to_le32(EXFAT_CLUSTER_FREE);

        for (i = 0; i < name_entries; i++)
        {
                struct exfat_entry_name* name_entry;

                name_entry = (struct exfat_entry_name*) &entries[2 + i];
                name_entry->type = EXFAT_ENTRY_FILE_NAME;
                name_entry->__unknown = 0;
                memcpy(name_entry->name, name + i * EXFAT_ENAME_MAX,
                                EXFAT_ENAME_MAX * sizeof(le16_t));
        }

        meta1->checksum = exfat_calc_checksum(entries, 2 + name_entries);
        rc = write_entries(ef, dir, entries, 2 + name_entries, offset);
        if (rc != 0)
                return rc;

        node = allocate_node();
        if (node == NULL)
                return -ENOMEM;
        node->entry_offset = offset;
        memcpy(node->name, name, name_length * sizeof(le16_t));
        init_node_meta1(node, meta1);
        init_node_meta2(node, meta2);

        tree_attach(dir, node);
        return 0;
}

static int create(struct exfat* ef, const char* path, uint16_t attrib)
{
        struct exfat_node* dir;
        struct exfat_node* existing;
        off_t offset = -1;
        le16_t name[EXFAT_NAME_MAX + 1];
        int rc;

        rc = exfat_split(ef, &dir, &existing, name, path);
        if (rc != 0)
                return rc;
        if (existing != NULL)
        {
                exfat_put_node(ef, existing);
                exfat_put_node(ef, dir);
                return -EEXIST;
        }

        rc = find_slot(ef, dir, &offset,
                        2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
        if (rc != 0)
        {
                exfat_put_node(ef, dir);
                return rc;
        }
        rc = commit_entry(ef, dir, name, offset, attrib);
        if (rc != 0)
        {
                exfat_put_node(ef, dir);
                return rc;
        }
        exfat_update_mtime(dir);
        rc = exfat_flush_node(ef, dir);
        exfat_put_node(ef, dir);
        return rc;
}

int exfat_mknod(struct exfat* ef, const char* path)
{
        return create(ef, path, EXFAT_ATTRIB_ARCH);
}

int exfat_mkdir(struct exfat* ef, const char* path)
{
        int rc;
        struct exfat_node* node;

        rc = create(ef, path, EXFAT_ATTRIB_DIR);
        if (rc != 0)
                return rc;
        rc = exfat_lookup(ef, &node, path);
        if (rc != 0)
                return 0;
        /* directories always have at least one cluster */
        rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
        if (rc != 0)
        {
                delete(ef, node);
                exfat_put_node(ef, node);
                return rc;
        }
        rc = exfat_flush_node(ef, node);
        if (rc != 0)
        {
                delete(ef, node);
                exfat_put_node(ef, node);
                return rc;
        }
        exfat_put_node(ef, node);
        return 0;
}

static int rename_entry(struct exfat* ef, struct exfat_node* dir,
                struct exfat_node* node, const le16_t* name, off_t new_offset)
{
        const size_t name_length = utf16_length(name);
        const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
        struct exfat_entry entries[2 + name_entries];
        struct exfat_entry_meta1* meta1 = (struct exfat_entry_meta1*) &entries[0];
        struct exfat_entry_meta2* meta2 = (struct exfat_entry_meta2*) &entries[1];
        int rc;
        int i;

        rc = read_entries(ef, node->parent, entries, 2, node->entry_offset);
        if (rc != 0)
                return rc;

        meta1->continuations = 1 + name_entries;
        meta2->name_length = name_length;
        meta2->name_hash = exfat_calc_name_hash(ef, name, name_length);

        rc = erase_node(ef, node);
        if (rc != 0)
                return rc;

        node->entry_offset = new_offset;
        node->continuations = 1 + name_entries;

        for (i = 0; i < name_entries; i++)
        {
                struct exfat_entry_name* name_entry;

                name_entry = (struct exfat_entry_name*) &entries[2 + i];
                name_entry->type = EXFAT_ENTRY_FILE_NAME;
                name_entry->__unknown = 0;
                memcpy(name_entry->name, name + i * EXFAT_ENAME_MAX,
                                EXFAT_ENAME_MAX * sizeof(le16_t));
        }

        meta1->checksum = exfat_calc_checksum(entries, 2 + name_entries);
        rc = write_entries(ef, dir, entries, 2 + name_entries, new_offset);
        if (rc != 0)
                return rc;

        memcpy(node->name, name, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
        tree_detach(node);
        tree_attach(dir, node);
        return 0;
}

int exfat_rename(struct exfat* ef, const char* old_path, const char* new_path)
{
        struct exfat_node* node;
        struct exfat_node* existing;
        struct exfat_node* dir;
        off_t offset = -1;
        le16_t name[EXFAT_NAME_MAX + 1];
        int rc;

        rc = exfat_lookup(ef, &node, old_path);
        if (rc != 0)
                return rc;

        rc = exfat_split(ef, &dir, &existing, name, new_path);
        if (rc != 0)
        {
                exfat_put_node(ef, node);
                return rc;
        }

        /* check that target is not a subdirectory of the source */
        if (node->attrib & EXFAT_ATTRIB_DIR)
        {
                struct exfat_node* p;

                for (p = dir; p; p = p->parent)
                        if (node == p)
                        {
                                if (existing != NULL)
                                        exfat_put_node(ef, existing);
                                exfat_put_node(ef, dir);
                                exfat_put_node(ef, node);
                                return -EINVAL;
                        }
        }

        if (existing != NULL)
        {
                /* remove target if it's not the same node as source */
                if (existing != node)
                {
                        if (existing->attrib & EXFAT_ATTRIB_DIR)
                        {
                                if (node->attrib & EXFAT_ATTRIB_DIR)
                                        rc = exfat_rmdir(ef, existing);
                                else
                                        rc = -ENOTDIR;
                        }
                        else
                        {
                                if (!(node->attrib & EXFAT_ATTRIB_DIR))
                                        rc = exfat_unlink(ef, existing);
                                else
                                        rc = -EISDIR;
                        }
                        exfat_put_node(ef, existing);
                        if (rc != 0)
                        {
                                /* free clusters even if something went wrong; overwise they
                                   will be just lost */
                                exfat_cleanup_node(ef, existing);
                                exfat_put_node(ef, dir);
                                exfat_put_node(ef, node);
                                return rc;
                        }
                        rc = exfat_cleanup_node(ef, existing);
                        if (rc != 0)
                        {
                                exfat_put_node(ef, dir);
                                exfat_put_node(ef, node);
                                return rc;
                        }
                }
                else
                        exfat_put_node(ef, existing);
        }

        rc = find_slot(ef, dir, &offset,
                        2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
        if (rc != 0)
        {
                exfat_put_node(ef, dir);
                exfat_put_node(ef, node);
                return rc;
        }
        rc = rename_entry(ef, dir, node, name, offset);
        if (rc != 0)
        {
                exfat_put_node(ef, dir);
                exfat_put_node(ef, node);
                return rc;
        }
        rc = exfat_flush_node(ef, dir);
        exfat_put_node(ef, dir);
        exfat_put_node(ef, node);
        /* node itself is not marked as dirty, no need to flush it */
        return rc;
}

void exfat_utimes(struct exfat_node* node, const struct timespec tv[2])
{
        node->atime = tv[0].tv_sec;
        node->mtime = tv[1].tv_sec;
        node->is_dirty = true;
}

void exfat_update_atime(struct exfat_node* node)
{
        node->atime = time(NULL);
        node->is_dirty = true;
}

void exfat_update_mtime(struct exfat_node* node)
{
        node->mtime = time(NULL);
        node->is_dirty = true;
}

const char* exfat_get_label(struct exfat* ef)
{
        return ef->label;
}

static int find_label(struct exfat* ef, off_t* offset)
{
        struct exfat_entry entry;
        int rc;

        for (*offset = 0; ; *offset += sizeof(entry))
        {
                rc = read_entries(ef, ef->root, &entry, 1, *offset);
                if (rc != 0)
                        return rc;

                if (entry.type == EXFAT_ENTRY_LABEL)
                        return 0;
        }
}

int exfat_set_label(struct exfat* ef, const char* label)
{
        le16_t label_utf16[EXFAT_ENAME_MAX + 1];
        int rc;
        off_t offset;
        struct exfat_entry_label entry;

        memset(label_utf16, 0, sizeof(label_utf16));
        rc = utf8_to_utf16(label_utf16, label, EXFAT_ENAME_MAX + 1, strlen(label));
        if (rc != 0)
                return rc;

        rc = find_label(ef, &offset);
        if (rc == -ENOENT)
                rc = find_slot(ef, ef->root, &offset, 1);
        if (rc != 0)
                return rc;

        entry.type = EXFAT_ENTRY_LABEL;
        entry.length = utf16_length(label_utf16);
        memcpy(entry.name, label_utf16, sizeof(entry.name));
        if (entry.length == 0)
                entry.type ^= EXFAT_ENTRY_VALID;

        rc = write_entries(ef, ef->root, (struct exfat_entry*) &entry, 1, offset);
        if (rc != 0)
                return rc;

        strcpy(ef->label, label);
        return 0;
}