/**

  * $Id$

  *

  * VMU volume (ie block device) support

  *

  * Copyright (c) 2009 Nathan Keynes.

  *

  * 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.

  */

 #include <glib/gmem.h>

 #include <glib/gstrfuncs.h>

 #include <string.h>

 #include <unistd.h>

 #include <stdio.h>

 #include <fcntl.h>

 #include <errno.h>

 #include "vmu/vmuvol.h"

 #include "dream.h"

 #include "lxpaths.h"

 #define VMU_MAX_PARTITIONS 256

 #define VMU_MAX_BLOCKS 65536 /* Actually slightly less than this, but it'll do */

 typedef struct vmu_partition {

     struct vmu_volume_metadata metadata;

     uint32_t block_count;

     char *blocks;

 } *vmu_partition_t;

 struct vmu_volume {

     const gchar *display_name;

     vmu_partnum_t part_count;

     gboolean dirty;

     struct vmu_partition part[0];

 };

 /* On-VMU structures, courtesy of Marcus Comstedt */ 

 struct vmu_superblock {

     char magic[16];

     uint8_t colour_flag;

     uint8_t bgra[4];

     uint8_t pad1[27];

     char timestamp[8];

     char pad2[8];

     char unknown[6];

     uint16_t fat_block;

     uint16_t fat_size;

     uint16_t dir_block;

     uint16_t dir_size;

     uint16_t icon_shape;

     uint16_t user_size;

     /* remainder unknown */

 };

 struct vmu_direntry {

     uint8_t filetype;

     uint8_t copy_flag;

     uint16_t blkno;

     char filename[12];

     char timestamp[8];

     uint16_t blksize; /* Size in blocks*/

     uint16_t hdroff; /* Header offset in blocks */

     char pad[4];

 };

 #define MD(vmu,ptno) ((vmu)->part[ptno].metadata)

 #define VMU_BLOCK(vmu,ptno,blkno) (&(vmu)->part[ptno].blocks[(blkno)*VMU_BLOCK_SIZE])

 #define VMU_FAT_ENTRY(vmu,pt,ent)  ((uint16_t *)VMU_BLOCK(vmu, pt, (MD(vmu,pt).fat_block - ((ent)>>8))))[(ent)&0xFF]

 #define FAT_EMPTY 0xFFFC

 #define FAT_EOF   0xFFFA

 static const struct vmu_volume_metadata default_metadata = { 255, 255, 254, 1, 253, 13, 0, 200, 31, 0, 128 };

 vmu_volume_t vmu_volume_new_default( const gchar *display_name )

 {

     vmu_volume_t vol = g_malloc0( sizeof(struct vmu_volume) + sizeof(struct vmu_partition) );

     vol->part_count = 1;

     vol->dirty = FALSE;

     memcpy( &vol->part[0].metadata, &default_metadata, sizeof(struct vmu_volume_metadata) );

     vol->part[0].block_count = VMU_DEFAULT_VOL_BLOCKS;

     vol->part[0].blocks = g_malloc0( VMU_DEFAULT_VOL_BLOCKS * VMU_BLOCK_SIZE );

     vol->display_name = display_name == NULL ? NULL : g_strdup(display_name);

     vmu_volume_format( vol, 0, TRUE );

     return vol;

 }

 void vmu_volume_destroy( vmu_volume_t vol )

 {

     int i;

     if( vol == NULL )

         return;

     for( i=0; i<vol->part_count; i++ ) {

         g_free( vol->part[i].blocks );

         vol->part[i].blocks = NULL;

     }

     if( vol->display_name ) {

         g_free( (char *)vol->display_name );

         vol->display_name = NULL;

     }

     g_free(vol);

 }

 void vmu_volume_format( vmu_volume_t vol, vmu_partnum_t pt, gboolean quick )

 {

     if( pt >= vol->part_count ) {

         return;

     }

     if( !quick ) {

         /* Wipe it completely first */

         memset( vol->part[pt].blocks, 0, (vol->part[pt].block_count) * VMU_BLOCK_SIZE );

     }

     struct vmu_volume_metadata *meta = &vol->part[pt].metadata;

     unsigned int fatblkno = meta->fat_block;

     unsigned int dirblkno = meta->dir_block;

     /* Write superblock */

     struct vmu_superblock *super = (struct vmu_superblock *)VMU_BLOCK(vol,pt, meta->super_block);

     memset( super->magic, 0x55, 16 );

     memset( &super->colour_flag, 0, 240 ); /* Blank the rest for now */

     super->fat_block = meta->fat_block;

     super->fat_size = meta->fat_size;

     super->dir_block = meta->dir_block;

     super->user_size = meta->user_size;

     /* Write file allocation tables */

     int i,j;

     for( j=0; j<meta->fat_size; j++ ) {

         uint16_t *fat = (uint16_t *)VMU_BLOCK(vol,pt,fatblkno-j); 

         for( i=0; i<256; i++ ) {

             fat[i] = FAT_EMPTY;

         }

     }

     /* Fill in the system allocations in the FAT */

     for( i=0; i<meta->fat_size-1; i++ ) {

         VMU_FAT_ENTRY(vol,pt,fatblkno-i) = fatblkno-i-1;

     }

     VMU_FAT_ENTRY(vol,pt,fatblkno - i) = FAT_EOF;

     for( i=0; i<meta->dir_size-1; i++ ) {

         VMU_FAT_ENTRY(vol,pt,dirblkno-i) = dirblkno-i-1;

     }

     VMU_FAT_ENTRY(vol,pt,dirblkno-i) = FAT_EOF;

     /* If quick-format, blank the directory. Otherwise it's already been done */

     if( quick ) {

         memset( VMU_BLOCK(vol,pt,dirblkno-meta->dir_size+1),

                 0, meta->dir_size * VMU_BLOCK_SIZE );

     }

 }

 /*************************** File load/save ********************************/

 /**

  * Current file has 1 META chunk for all volume metadata, followed by a

  * DATA chunk for each partition's block data. The META chunk is required to

  * occur before any DATA blocks.

  * Unknown chunks are skipped to allow for forwards compatibility if/when

  * we add the VMU runtime side of things

  */

 struct vmu_file_header {

     char magic[16];

     uint32_t version;

     uint32_t head_len;

     uint32_t part_count;

     uint32_t display_name_len;

     char display_name[0];

 };

 struct vmu_chunk_header {

     char name[4];

     uint32_t length;

 };

 gboolean vmu_volume_save( const gchar *filename, vmu_volume_t vol, gboolean create_only )

 {

     struct vmu_file_header head;

     struct vmu_chunk_header chunk;

     int i;

     gchar *tempfile = get_filename_at(filename, ".XXXXXXX");

     int fd = mkstemp( tempfile );

     if( fd == -1 ) {

         g_free(tempfile);

         return FALSE;

     }

     FILE *f = fdopen( fd, "w+" );

     /* File header */

     memcpy( head.magic, VMU_FILE_MAGIC, 16 );

     head.version = VMU_FILE_VERSION;

     head.part_count = vol->part_count;

     head.display_name_len = vol->display_name == NULL ? 0 : (strlen(vol->display_name)+1);

     head.head_len = sizeof(head) + head.display_name_len;

     fwrite( &head, sizeof(head), 1, f );

     if( vol->display_name != NULL ) {

         fwrite( vol->display_name, head.display_name_len, 1, f );

     }

     /* METAdata chunk */

     memcpy( chunk.name, "META", 4 );

     chunk.length = sizeof(struct vmu_volume_metadata) * vol->part_count;

     fwrite( &chunk, sizeof(chunk), 1, f );

     for( i=0; i < vol->part_count; i++ ) {

         fwrite( &vol->part[i].metadata, sizeof(struct vmu_volume_metadata), 1, f );

     }

     /* partition DATA chunks */

     for( i=0; i< vol->part_count; i++ ) {

         memcpy( chunk.name, "DATA", 4 );

         chunk.length = 0;

         if( fwrite( &chunk, sizeof(chunk), 1, f ) != 1 ) goto cleanup;

         long posn = ftell(f);

         if( fwrite( &vol->part[i].block_count, sizeof(vol->part[i].block_count), 1, f ) != 1 ) goto cleanup;

         fwrite_gzip( vol->part[i].blocks, vol->part[i].block_count, VMU_BLOCK_SIZE, f );

         long end = ftell(f);

         fseek( f, posn - sizeof(chunk.length), SEEK_SET );

         chunk.length = end-posn;

         if( fwrite( &chunk.length, sizeof(chunk.length), 1, f ) != 1 ) goto cleanup;

         fseek( f, end, SEEK_SET );

     }

     fclose(f);

     if( rename(tempfile, filename) != 0 )

         goto cleanup;

     /* All good */

     vol->dirty = FALSE;

     g_free(tempfile);

     return TRUE;

 cleanup:

     fclose(f);

     unlink(tempfile);

     g_free(tempfile);

     return FALSE;

 }

 vmu_volume_t vmu_volume_load( const gchar *filename )

 {

     struct vmu_file_header head;

     struct vmu_chunk_header chunk;

     vmu_volume_t vol;

     int i;

     FILE *f = fopen( filename, "ro" );

     if( f == NULL ) {

         ERROR( "Unable to open VMU file '%s': %s", filename, strerror(errno) );

         return FALSE;

     }

     if( fread( &head, sizeof(head), 1, f ) != 1 ||

         memcmp(head.magic, VMU_FILE_MAGIC, 16) != 0 ||

         head.part_count > VMU_MAX_PARTITIONS || 

         head.head_len < (sizeof(head) + head.display_name_len) )  {

         fclose(f);

         ERROR( "Unable to load VMU '%s': bad file header", filename );

         return NULL;

     }

     vol = (vmu_volume_t)g_malloc0( sizeof(struct vmu_volume) + sizeof(struct vmu_partition)*head.part_count );

     vol->part_count = head.part_count;

     vol->dirty = FALSE;

     if( head.display_name_len != 0 ) {

         vol->display_name = g_malloc( head.display_name_len );

         fread( (char *)vol->display_name, head.display_name_len, 1, f );

     }

     fseek( f, head.head_len, SEEK_SET );

     gboolean have_meta = FALSE;

     int next_part = 0;

     while( !feof(f) && fread( &chunk, sizeof(chunk), 1, f ) == 1 ) {

         if( memcmp( &chunk.name, "META", 4 ) == 0 ) {

             if( have_meta || chunk.length != head.part_count * sizeof(struct vmu_volume_metadata) ) {

                 vmu_volume_destroy(vol);

                 fclose(f);

                 ERROR( "Unable to load VMU '%s': bad metadata size (expected %d but was %d)", filename,

                        head.part_count * sizeof(struct vmu_volume_metadata), chunk.length );

                 return NULL;

             }

             for( i=0; i<head.part_count; i++ ) {

                 fread( &vol->part[i].metadata, sizeof(struct vmu_volume_metadata), 1, f );

             }

             have_meta = TRUE;

         } else if( memcmp( &chunk.name, "DATA", 4 ) == 0 ) {

             uint32_t block_count;

             fread( &block_count, sizeof(block_count), 1, f );

             if( next_part >= vol->part_count || block_count >= VMU_MAX_BLOCKS ) {

                 // Too many partitions / blocks

                 vmu_volume_destroy(vol);

                 fclose(f);

                 ERROR( "Unable to load VMU '%s': too large (%d/%d)", filename, next_part, block_count );

                 return NULL;

             }

             vol->part[next_part].block_count = block_count;

             vol->part[next_part].blocks = g_malloc(block_count*VMU_BLOCK_SIZE);

             fread_gzip(vol->part[next_part].blocks, VMU_BLOCK_SIZE, block_count, f );

             next_part++;

         } else {

             // else skip unknown block

             fseek( f, SEEK_CUR, chunk.length );

             WARN( "Unexpected VMU data chunk: '%4.4s'", chunk.name );

         }

     }

     fclose(f);

     if( !have_meta || next_part != vol->part_count ) {

         vmu_volume_destroy( vol );

         return NULL;

     }

     return vol;

 }

 /*************************** Accessing data ********************************/

 const char *vmu_volume_get_display_name( vmu_volume_t vol ) 

 {

     return vol->display_name;

 }

 void vmu_volume_set_display_name( vmu_volume_t vol, const gchar *name )

 {

     if( vol->display_name != NULL ) {

         g_free( (char *)vol->display_name );

     }

     if( name == NULL ) {

         vol->display_name = NULL;

     } else {

         vol->display_name = g_strdup(name);

     }

 }

 gboolean vmu_volume_is_dirty( vmu_volume_t vol )

 {

     return vol->dirty;

 }

 gboolean vmu_volume_read_block( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned char *out )

 {

     if( pt >= vol->part_count || block >= vol->part[pt].block_count ) {

         return FALSE;

     }

     memcpy( out, VMU_BLOCK(vol,pt,block), VMU_BLOCK_SIZE );

     return TRUE;

 }

 gboolean vmu_volume_write_block( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned char *in )

 {

     if( pt >= vol->part_count || block >= vol->part[pt].block_count ) {

         return FALSE;

     }

     memcpy( VMU_BLOCK(vol,pt,block), in, VMU_BLOCK_SIZE );

     vol->dirty = TRUE;

 }

 gboolean vmu_volume_write_phase( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned int phase, unsigned char *in )

 {

     if( pt >= vol->part_count || block >= vol->part[pt].block_count || phase >= 4 ) {

         return FALSE;

     }

     memcpy( VMU_BLOCK(vol,pt,block) + (phase*128), in, VMU_BLOCK_SIZE/4 );

     vol->dirty = TRUE;

 }

 const struct vmu_volume_metadata *vmu_volume_get_metadata( vmu_volume_t vol, vmu_partnum_t partition )

 {

     if( partition >= vol->part_count ) {

         return NULL;

     } else {

         return &vol->part[partition].metadata;

     }

 }