478 lines
15 KiB
C
478 lines
15 KiB
C
#include "fat12.h"
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#include "fat12-internals.h"
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#include "io.h"
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#include <stdio.h>
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#include <ctype.h>
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struct fat12_partition
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{
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struct pang_io *io;
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// Number of bytes in a sector (512)
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uint32_t sector_size;
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uint8_t sector_buffer[512];
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// These units are "sectors"
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uint32_t fat_offset;
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uint32_t fat_size;
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uint32_t root_offset;
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uint32_t first_offset;
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uint32_t cluster_size;
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// These are in single-unit quantities
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uint32_t root_entries;
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uint32_t cluster_count;
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uint32_t cluster_bytes;
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uint32_t sector_count;
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// Used for traversing directories
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uint32_t current_cluster;
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void *fat;
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};
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void fat12_write_u8(void *ptr, uint8_t val)
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{
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((uint8_t *)ptr)[0] = (val >> 0) & 0xff;
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}
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uint8_t fat12_read_u8(void *ptr)
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{
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uint16_t val = 0;
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val |= (((uint8_t *)ptr)[0] << 0) & 0xff;
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return val;
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}
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void fat12_write_u16(void *ptr, uint16_t val)
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{
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((uint8_t *)ptr)[0] = (val >> 0) & 0xff;
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((uint8_t *)ptr)[1] = (val >> 8) & 0xff;
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}
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uint16_t fat12_read_u16(void *ptr)
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{
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uint16_t val = 0;
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val |= (((uint8_t *)ptr)[0] << 0) & 0x00ff;
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val |= (((uint8_t *)ptr)[1] << 8) & 0xff00;
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return val;
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}
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void fat12_write_u32(void *ptr, uint32_t val)
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{
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((uint8_t *)ptr)[0] = (val >> 0) & 0xff;
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((uint8_t *)ptr)[1] = (val >> 8) & 0xff;
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((uint8_t *)ptr)[2] = (val >> 16) & 0xff;
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((uint8_t *)ptr)[3] = (val >> 24) & 0xff;
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}
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uint32_t fat12_read_u32(void *ptr)
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{
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uint16_t val = 0;
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val |= (((uint8_t *)ptr)[0] << 0) & 0x000000ff;
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val |= (((uint8_t *)ptr)[1] << 8) & 0x0000ff00;
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val |= (((uint8_t *)ptr)[2] << 16) & 0x00ff0000;
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val |= (((uint8_t *)ptr)[3] << 24) & 0xff000000;
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return val;
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}
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void fat12_set_cluster(void *fat, uint32_t cluster, uint32_t value)
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{
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uint32_t offset = (cluster * 3) / 2;
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// fprintf(stderr, "Cluster %d -> %03x (%02x%02x -> ", cluster, value, ((uint8_t *)fat)[offset], ((uint8_t *)fat)[offset + 1]);
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if (cluster & 1)
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{
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((uint8_t *)fat)[offset] = (((uint8_t *)fat)[offset] & 0x0f) | ((value << 4) & 0xf0);
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((uint8_t *)fat)[offset + 1] = value >> 4;
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}
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else
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{
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((uint8_t *)fat)[offset] = value;
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((uint8_t *)fat)[offset + 1] = (((uint8_t *)fat)[offset + 1] & 0xf0) | ((value >> 8) & 0x0f);
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}
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// fprintf(stderr, "%02x%02x)\n", ((uint8_t *)fat)[offset], ((uint8_t *)fat)[offset + 1]);
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}
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uint32_t fat12_get_cluster(void *fat, uint32_t cluster)
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{
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uint32_t offset = (cluster * 3) / 2;
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uint32_t value = 0;
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if (cluster & 1)
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{
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value |= (((uint8_t *)fat)[offset] >> 4) & 0x00f;
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value |= (((uint8_t *)fat)[offset + 1] << 4) & 0xff0;
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}
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else
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{
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value |= ((uint8_t *)fat)[offset];
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value |= (((uint8_t *)fat)[offset + 1] << 8) & 0xf00;
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}
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// fprintf(stderr, "Cluster %d <- %03x\n", cluster, value);
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return value;
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}
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struct fat12_partition *fat12_alloc(void)
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{
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struct fat12_partition *part = malloc(sizeof(struct fat12_partition));
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memset(part, 0, sizeof(*part));
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return part;
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}
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int fat12_open(struct fat12_partition *part, const char *filename)
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{
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if (!part)
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return -1;
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if (part->io)
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return -1;
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part->io = pang_open(filename);
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if (!part->io)
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return -1;
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if (pang_read(part->io, 0, part->sector_buffer, sizeof(part->sector_buffer)) != sizeof(part->sector_buffer))
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return -1;
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part->sector_size = fat12_read_u16(part->sector_buffer + 0x0b);
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// These are in single-unit quantities
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part->root_entries = fat12_read_u16(part->sector_buffer + 0x11);
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part->sector_count = fat12_read_u16(part->sector_buffer + 0x13);
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// These units are "sectors"
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part->fat_offset = fat12_read_u16(part->sector_buffer + 0x0e);
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part->fat_size = fat12_read_u16(part->sector_buffer + 0x16);
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part->root_offset = part->fat_offset + part->fat_size;
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part->first_offset = part->root_offset + (part->root_entries * sizeof(struct fat_directory_entry)) / part->sector_size;
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part->cluster_size = fat12_read_u8(part->sector_buffer + 0x0d);
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uint32_t bytes = (part->sector_count - part->first_offset) * part->sector_size;
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part->cluster_count = bytes / part->sector_size / part->cluster_size;
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part->cluster_bytes = (part->cluster_count * 3) / 2;
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// Move to the root directory
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part->current_cluster = part->first_offset;
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///
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fprintf(stderr, "part->sector_size: %d\n", part->sector_size);
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// These are in single-unit quantities
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fprintf(stderr, "part->root_entries: %d\n", part->root_entries);
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fprintf(stderr, "part->sector_count: %d\n", part->sector_count);
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// These units are "sectors"
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fprintf(stderr, "part->fat_offset: %d\n", part->fat_offset);
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fprintf(stderr, "part->fat_size: %d\n", part->fat_size);
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fprintf(stderr, "part->root_offset: %d\n", part->root_offset);
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fprintf(stderr, "part->first_offset: %d\n", part->first_offset);
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fprintf(stderr, "part->cluster_size: %d\n", part->cluster_size);
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fprintf(stderr, "part->cluster_count: %d\n", part->cluster_count);
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fprintf(stderr, "part->cluster_bytes: %d\n", part->cluster_bytes);
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fprintf(stderr, "data_bytes: %d\n", bytes);
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///
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if (1)
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{
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part->fat = malloc(part->fat_size * part->sector_size);
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pang_read(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
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}
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return 0;
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}
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void fat12_reload(struct fat12_partition *part)
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{
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pang_read(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
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}
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static int fat12_ls_foreach_sector(struct fat12_partition *part, uint32_t sector, uint32_t count,
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void *data, int (*callback)(void *data, const struct fat12_dirent *dirent))
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{
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struct fat12_dirent dirent;
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uint8_t buf[part->sector_size];
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uint32_t offset;
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pang_read(part->io, sector * part->sector_size, buf, sizeof(buf));
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for (offset = 0; offset < count; offset++)
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{
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struct fat_directory_entry *entry = &((struct fat_directory_entry *)buf)[offset];
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memset(&dirent, 0, sizeof(dirent));
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memcpy(dirent.filename, entry->file_name, 8);
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memcpy(dirent.filename + 8, entry->extension, 3);
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dirent.first_cluster = fat12_read_u16(&entry->first_cluster);
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dirent.size = fat12_read_u32(&entry->file_size);
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if ((entry->file_name[0] != 0xe5) && (entry->file_name[0] != 0x00))
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callback(data, &dirent);
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}
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return 0;
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}
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int fat12_ls_foreach(struct fat12_partition *part, uint32_t dir_cluster, void *data, int (*callback)(void *data, const struct fat12_dirent *dirent))
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{
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uint32_t sector;
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if (dir_cluster < 2)
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{
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sector = part->root_offset;
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uint32_t dir_entries;
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uint32_t max_entries = part->root_entries;
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uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
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uint32_t loop = 0;
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for (dir_entries = 0; dir_entries < max_entries; dir_entries += entries_per_sector)
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{
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uint32_t entries_to_list = entries_per_sector;
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if (max_entries - dir_entries < entries_to_list)
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entries_to_list = max_entries - dir_entries;
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fat12_ls_foreach_sector(part, part->root_offset + loop++, entries_to_list, data, callback);
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}
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}
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else
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{
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sector = dir_cluster * part->cluster_size + part->first_offset;
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while (dir_cluster > 1 && dir_cluster < 0xff8)
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{
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// dir_cluster = fat12_get_cluster(part->fd, dir_cluster);
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}
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}
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return 0;
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}
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void fat12_flush(struct fat12_partition *part)
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{
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pang_write(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
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}
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int fat12_close(struct fat12_partition *part)
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{
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if (!part)
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return -1;
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if (1)
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{
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fat12_flush(part);
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free(part->fat);
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}
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if (-1 == pang_close(&part->io))
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{
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return -1;
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}
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return 0;
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}
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void fat12_free(struct fat12_partition **part)
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{
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if (!part)
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return;
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if (!*part)
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return;
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if ((*part)->io)
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fat12_close(*part);
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free(*part);
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*part = NULL;
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}
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static uint32_t fat12_find_free_cluster(struct fat12_partition *part, uint32_t start)
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{
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uint32_t cluster_value;
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if (start < 1)
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start = 1;
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do
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{
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cluster_value = fat12_get_cluster(part->fat, ++start);
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fprintf(stderr, "Cluster %d value: %03x\n", start, cluster_value);
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} while (cluster_value != 0);
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fprintf(stderr, "Found free cluster %d\n", start);
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return start;
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}
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static int fat12_add_dirent_sector(struct fat12_partition *part, uint32_t sector, uint32_t count, const struct fat_directory_entry *new_dirent)
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{
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struct fat12_dirent dirent;
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uint8_t buf[part->sector_size];
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uint32_t offset;
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pang_read(part->io, sector * part->sector_size, buf, sizeof(buf));
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for (offset = 0; offset < count; offset++)
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{
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struct fat_directory_entry *entry = &((struct fat_directory_entry *)buf)[offset];
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memset(&dirent, 0, sizeof(dirent));
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memcpy(dirent.filename, entry->file_name, 8);
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memcpy(dirent.filename + 8, entry->extension, 3);
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dirent.first_cluster = fat12_read_u16(&entry->first_cluster);
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dirent.size = fat12_read_u32(&entry->file_size);
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if ((entry->file_name[0] == 0xe5) || (entry->file_name[0] == 0x00))
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{
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((struct fat_directory_entry *)buf)[offset] = *new_dirent;
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pang_write(part->io, sector * part->sector_size, buf, sizeof(buf));
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return 0;
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}
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}
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return -1;
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}
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static int fat12_dir_update_or_add_dirent(struct fat12_partition *part, uint32_t dir_cluster, const struct fat_directory_entry *dirent)
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{
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if (1)
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{
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uint32_t sector = part->root_offset;
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uint32_t dir_entries;
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uint32_t max_entries = part->root_entries;
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uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
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uint32_t loop = 0;
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for (dir_entries = 0; dir_entries < max_entries; dir_entries += entries_per_sector)
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{
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uint32_t entries_to_list = entries_per_sector;
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if (max_entries - dir_entries < entries_to_list)
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entries_to_list = max_entries - dir_entries;
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// TODO: See if a filename already exists
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if (!fat12_add_dirent_sector(part, part->root_offset + loop++, entries_to_list, dirent))
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return 0;
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}
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}
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return 0;
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}
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static void fat_dirent_set_name(struct fat_directory_entry *dirent, const char *filename)
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{
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int i;
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int ext_split = -1;
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int name_off = 0;
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int dirent_off = 0;
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for (name_off = 0; filename[name_off] != '\0'; name_off++)
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{
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if (filename[name_off] == '.')
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ext_split = name_off + 1;
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}
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for (dirent_off = 0; dirent_off < 8; dirent_off++)
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{
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if (dirent_off < (ext_split - 1))
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dirent->file_name[dirent_off] = toupper(filename[dirent_off]);
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else
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dirent->file_name[dirent_off] = ' ';
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}
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name_off = ext_split + 1;
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for (dirent_off = 0; dirent_off < 3; dirent_off++)
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{
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if ((ext_split >= 0) && (filename[ext_split]))
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dirent->extension[dirent_off] = toupper(filename[ext_split++]);
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else
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dirent->extension[dirent_off] = ' ';
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}
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}
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int fat12_write_file(struct fat12_partition *part, const char *filename, const void *bfr, uint32_t size)
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{
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// TODO: directory support
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uint32_t first_cluster;
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uint32_t cluster;
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cluster = first_cluster = fat12_find_free_cluster(part, 1);
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struct fat_directory_entry dirent;
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memset(&dirent, 0, sizeof(dirent));
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fat_dirent_set_name(&dirent, filename);
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dirent.file_attributes = 0x20;
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dirent.reserved1 = 0x18;
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fat12_write_u16(dirent.first_cluster, first_cluster);
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fat12_write_u32(dirent.file_size, size);
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fat12_dir_update_or_add_dirent(part, 0, &dirent);
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while (size > 0)
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{
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uint32_t bytes_to_write = size;
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if (bytes_to_write > part->cluster_size * part->sector_size)
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bytes_to_write = part->cluster_size * part->sector_size;
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pang_write(part->io,
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((cluster - 2) * part->cluster_size + part->first_offset) * part->sector_size,
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bfr,
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bytes_to_write);
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size -= bytes_to_write;
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fprintf(stderr, "%s: %d bytes left\n", filename, size);
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if (!size)
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fat12_set_cluster(part->fat, cluster, 0xff8);
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else
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{
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uint32_t next_cluster = fat12_find_free_cluster(part, cluster);
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fat12_set_cluster(part->fat, cluster, next_cluster);
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cluster = next_cluster;
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}
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}
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}
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static uint32_t find_root_cluster_for_file(struct fat12_partition *part, const char *filename)
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{
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uint32_t file_cluster = 0;
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// Find the dirent of the file
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uint32_t dirent_cluster = 0;
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// TODO: Support directories other than the root directory
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if (1)
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{
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struct fat_directory_entry dirent;
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uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
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fat_dirent_set_name(&dirent, filename);
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int i = 0;
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int check_entry_i;
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int sector = part->root_offset - 1; // -1 because we use it to update the entry below.
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while (i < part->root_entries)
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{
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struct fat_directory_entry entries[entries_per_sector];
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pang_read(part->io, ++sector * part->sector_size, entries, sizeof(entries));
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for (check_entry_i = 0; (check_entry_i < entries_per_sector) && (i < part->root_entries); check_entry_i++, i++)
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{
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if (!memcmp(&entries[check_entry_i], &dirent, 11))
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{
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entries[check_entry_i].file_name[0] = 0xe5;
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pang_write(part->io, sector * part->sector_size, entries, sizeof(entries));
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return fat12_read_u16(entries[check_entry_i].first_cluster);
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}
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}
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}
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}
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return 0;
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}
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int fat12_delete_file(struct fat12_partition *part, const char *filename)
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{
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// Find the root cluster of the file
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uint32_t root_cluster = find_root_cluster_for_file(part, filename);
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// A return value of 0 (or 1) is not a valid cluster, so there's
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// nothing to do.
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if (root_cluster < 2)
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{
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return 0;
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}
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// Change the first character of the dirent to 0xe5 to indicate
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// it's been deleted.
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// Set all clusters in the FAT to 0x000, indicating they're free.
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uint32_t this_cluster = root_cluster;
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do
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{
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uint32_t next_cluster = fat12_get_cluster(part->fat, this_cluster);
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// fprintf(stderr, "This cluster: %03d Next cluster: %03d Next-next cluster: %03d\n", this_cluster, next_cluster, next_next_cluster);
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fat12_set_cluster(part->fat, this_cluster, 0);
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this_cluster = next_cluster;
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} while ((this_cluster < 0xff8) && (this_cluster > 1));
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return 0;
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} |