mass WIP commit

Signed-off-by: Sean Cross <sean@xobs.io>

Makefile

@@ -1,6 +1,6 @@
 CFLAGS ?= -Iinclude -ggdb2
 
-all: build build/test-get-set-cluster build/test-mkfs-simple build/test-fragment-file
+all: build build/test-get-set-cluster build/test-mkfs-simple build/test-fragment-file build/pangtool
 
 build:
 	mkdir build
@@ -12,4 +12,7 @@ build/test-mkfs-simple: tests/mkfs-simple.c src/fat12.c include/fat12.h src/mkfa
 	$(CC) $(CFLAGS) tests/mkfs-simple.c src/mkfat.c src/fat12.c src/io.c -o $@
 
 build/test-fragment-file: tests/fragment-file.c src/fat12.c include/fat12.h src/mkfat.c src/io.c include/io.h
-	$(CC) $(CFLAGS) tests/fragment-file.c src/mkfat.c src/fat12.c src/io.c -o $@
+	$(CC) $(CFLAGS) tests/fragment-file.c src/mkfat.c src/fat12.c src/io.c -o $@
+
+build/pangtool: tests/pangtool.c src/fat12.c include/fat12.h src/mkfat.c src/file.c src/io.c include/io.h
+	$(CC) $(CFLAGS) tests/pangtool.c src/mkfat.c src/fat12.c src/io.c src/file.c -o $@

include/fat12-internals.h

@@ -17,4 +17,37 @@ struct fat_directory_entry {
     uint8_t file_size[4];
 };
 
+
+struct fat12_partition
+{
+    struct pang_io *io;
+
+    // Number of bytes in a sector (512)
+    uint32_t sector_size;
+    uint8_t sector_buffer[512];
+
+    // These units are "sectors"
+    uint32_t fat_offset;
+    uint32_t fat_size;
+    uint32_t root_offset;
+    uint32_t first_offset;
+    uint32_t cluster_size;
+
+    // These are in single-unit quantities
+    uint32_t root_entries;
+    uint32_t cluster_count;
+    uint32_t cluster_bytes;
+    uint32_t sector_count;
+
+    void *fat;
+    uint16_t *taf;
+};
+
+enum fat_attributes {
+    FAT_ATTR_DIR  = 0x10,
+    FAT_ATTR_FILE = 0x20,
+};
+
+uint32_t fat12_find_free_cluster(struct fat12_partition *part, uint32_t start);
+
 #endif /* FAT12_INTERNALS_H__ */

include/fat12.h

@@ -5,10 +5,12 @@
 
 struct pang_io;
 struct fat12_partition;
+struct fat12_file;
 struct fat12_dirent
 {
     char filename[256];
     uint32_t first_cluster;
+    uint32_t parent_cluster;
     uint32_t size;
     uint32_t file_attributes;
     uint32_t ctime;
@@ -33,8 +35,14 @@ uint32_t fat12_get_cluster(void *fat, uint32_t cluster);
 
 int fat12_ls_foreach(struct fat12_partition *part, uint32_t dir_cluster,
                      void *data, int (*callback)(void *data, const struct fat12_dirent *dirent));
-int fat12_write_file(struct fat12_partition *part, const char *filename, const void *bfr, uint32_t size);
+int fat12_write_file(struct fat12_partition *part, const char *filename[], const void *bfr, uint32_t size);
-int fat12_delete_file(struct fat12_partition *part, const char *filename);
+int fat12_delete_file(struct fat12_partition *part, const char *filename[]);
+int fat12_defragment_file(struct fat12_partition *part, const char *path[]);
+
+struct fat12_file *fat12_fopen(struct fat12_partition *part, const char *filename);
+int fat12_fwrite(struct fat12_file *file, const void *buf, uint32_t size);
+int fat12_fread(struct fat12_file *file, void *buf, uint32_t size);
+int fat12_fclose(struct fat12_file **file);
 
 int fat12_defrag(struct pang_io *io);
 int fat12_mkfs(struct pang_io *io, uint32_t bytes);

src/fat12.c

@@ -2,34 +2,16 @@
 #include "fat12-internals.h"
 #include "io.h"
 
+#ifdef DEBUG
 #include <stdio.h>
+#endif
 #include <ctype.h>
 
-struct fat12_partition
+struct fat_dirent_ptr
 {
-    struct pang_io *io;
+    struct fat_directory_entry entry;
-
+    uint32_t sector;
-    // Number of bytes in a sector (512)
+    uint32_t offset;
-    uint32_t sector_size;
-    uint8_t sector_buffer[512];
-
-    // These units are "sectors"
-    uint32_t fat_offset;
-    uint32_t fat_size;
-    uint32_t root_offset;
-    uint32_t first_offset;
-    uint32_t cluster_size;
-
-    // These are in single-unit quantities
-    uint32_t root_entries;
-    uint32_t cluster_count;
-    uint32_t cluster_bytes;
-    uint32_t sector_count;
-
-    // Used for traversing directories
-    uint32_t current_cluster;
-
-    void *fat;
 };
 
 void fat12_write_u8(void *ptr, uint8_t val)
@@ -114,6 +96,37 @@ uint32_t fat12_get_cluster(void *fat, uint32_t cluster)
     return value;
 }
 
+static void fat_dirent_set_name(struct fat_directory_entry *dirent, const char *filename)
+{
+    int i;
+    int ext_split = -1;
+    int name_off = 0;
+    int dirent_off = 0;
+
+    for (name_off = 0; filename[name_off] != '\0'; name_off++)
+    {
+        if (filename[name_off] == '.')
+            ext_split = name_off + 1;
+    }
+
+    for (dirent_off = 0; dirent_off < 8; dirent_off++)
+    {
+        if (dirent_off < (ext_split - 1))
+            dirent->file_name[dirent_off] = toupper(filename[dirent_off]);
+        else
+            dirent->file_name[dirent_off] = ' ';
+    }
+
+    name_off = ext_split + 1;
+    for (dirent_off = 0; dirent_off < 3; dirent_off++)
+    {
+        if ((ext_split >= 0) && (filename[ext_split]))
+            dirent->extension[dirent_off] = toupper(filename[ext_split++]);
+        else
+            dirent->extension[dirent_off] = ' ';
+    }
+}
+
 struct fat12_partition *fat12_alloc(void)
 {
     struct fat12_partition *part = malloc(sizeof(struct fat12_partition));
@@ -121,73 +134,12 @@ struct fat12_partition *fat12_alloc(void)
     return part;
 }
 
-int fat12_open(struct fat12_partition *part, const char *filename)
+static uint32_t cluster_for_sector(struct fat12_partition *part, uint32_t sector) {
-{
+    return ((sector - part->first_offset) / part->cluster_size) + 2;
-
-    if (!part)
-        return -1;
-
-    if (part->io)
-        return -1;
-
-    part->io = pang_open(filename);
-    if (!part->io)
-        return -1;
-
-    if (pang_read(part->io, 0, part->sector_buffer, sizeof(part->sector_buffer)) != sizeof(part->sector_buffer))
-        return -1;
-
-    part->sector_size = fat12_read_u16(part->sector_buffer + 0x0b);
-
-    // These are in single-unit quantities
-    part->root_entries = fat12_read_u16(part->sector_buffer + 0x11);
-    part->sector_count = fat12_read_u16(part->sector_buffer + 0x13);
-
-    // These units are "sectors"
-    part->fat_offset = fat12_read_u16(part->sector_buffer + 0x0e);
-    part->fat_size = fat12_read_u16(part->sector_buffer + 0x16);
-    part->root_offset = part->fat_offset + part->fat_size;
-    part->first_offset = part->root_offset + (part->root_entries * sizeof(struct fat_directory_entry)) / part->sector_size;
-    part->cluster_size = fat12_read_u8(part->sector_buffer + 0x0d);
-
-    uint32_t bytes = (part->sector_count - part->first_offset) * part->sector_size;
-    part->cluster_count = bytes / part->sector_size / part->cluster_size;
-    part->cluster_bytes = (part->cluster_count * 3) / 2;
-
-    // Move to the root directory
-    part->current_cluster = part->first_offset;
-
-    ///
-    fprintf(stderr, "part->sector_size: %d\n", part->sector_size);
-
-    // These are in single-unit quantities
-    fprintf(stderr, "part->root_entries: %d\n", part->root_entries);
-    fprintf(stderr, "part->sector_count: %d\n", part->sector_count);
-
-    // These units are "sectors"
-    fprintf(stderr, "part->fat_offset: %d\n", part->fat_offset);
-    fprintf(stderr, "part->fat_size: %d\n", part->fat_size);
-    fprintf(stderr, "part->root_offset: %d\n", part->root_offset);
-    fprintf(stderr, "part->first_offset: %d\n", part->first_offset);
-    fprintf(stderr, "part->cluster_size: %d\n", part->cluster_size);
-
-    fprintf(stderr, "part->cluster_count: %d\n", part->cluster_count);
-    fprintf(stderr, "part->cluster_bytes: %d\n", part->cluster_bytes);
-    fprintf(stderr, "data_bytes: %d\n", bytes);
-    ///
-
-    if (1)
-    {
-        part->fat = malloc(part->fat_size * part->sector_size);
-        pang_read(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
-    }
-
-    return 0;
 }
 
-void fat12_reload(struct fat12_partition *part)
+static uint32_t sector_for_cluster(struct fat12_partition *part, uint32_t cluster) {
-{
+    return ((cluster - 2) * part->cluster_size) + part->first_offset;
-    pang_read(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
 }
 
 static int fat12_ls_foreach_sector(struct fat12_partition *part, uint32_t sector, uint32_t count,
@@ -206,6 +158,8 @@ static int fat12_ls_foreach_sector(struct fat12_partition *part, uint32_t sector
         memcpy(dirent.filename + 8, entry->extension, 3);
         dirent.first_cluster = fat12_read_u16(&entry->first_cluster);
         dirent.size = fat12_read_u32(&entry->file_size);
+        dirent.file_attributes = entry->file_attributes;
+        dirent.parent_cluster = sector_for_cluster(part, sector);
 
         if ((entry->file_name[0] != 0xe5) && (entry->file_name[0] != 0x00))
             callback(data, &dirent);
@@ -243,6 +197,99 @@ int fat12_ls_foreach(struct fat12_partition *part, uint32_t dir_cluster, void *d
     return 0;
 }
 
+static int update_taf(void *_part, const struct fat12_dirent *dir) {
+    struct fat12_partition *part = _part;
+    ((uint16_t *)part->taf)[dir->first_cluster] = 0x8000 | dir->parent_cluster;
+    uint32_t last_cluster = dir->first_cluster;
+    while (1) {
+        uint32_t cluster = fat12_get_cluster(part->fat, last_cluster);
+
+        if ((cluster == 0) || (cluster >= 0xff8)) {
+            break;
+        }
+        ((uint16_t *)part->taf)[cluster] = last_cluster;
+        last_cluster = cluster;
+    }
+
+    if (dir->file_attributes & FAT_ATTR_DIR)
+        fat12_ls_foreach(part, sector_for_cluster(part, dir->first_cluster), part, update_taf);
+}
+
+void fat12_reload(struct fat12_partition *part)
+{
+    pang_read(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
+    memset(part->taf, 0, sizeof(part->taf));
+    fat12_ls_foreach(part, 0, part, update_taf);
+}
+
+int fat12_open(struct fat12_partition *part, const char *filename)
+{
+
+    if (!part)
+        return -1;
+
+    if (part->io)
+        return -1;
+
+    part->io = pang_open(filename);
+    if (!part->io)
+        return -1;
+
+    if (pang_read(part->io, 0, part->sector_buffer, sizeof(part->sector_buffer)) != sizeof(part->sector_buffer))
+    {
+        if (!errno)
+            errno = -ENOSPC;
+        return -1;
+    }
+
+    part->sector_size = fat12_read_u16(part->sector_buffer + 0x0b);
+
+    // These are in single-unit quantities
+    part->root_entries = fat12_read_u16(part->sector_buffer + 0x11);
+    part->sector_count = fat12_read_u16(part->sector_buffer + 0x13);
+
+    // These units are "sectors"
+    part->fat_offset = fat12_read_u16(part->sector_buffer + 0x0e);
+    part->fat_size = fat12_read_u16(part->sector_buffer + 0x16);
+    part->root_offset = part->fat_offset + part->fat_size;
+    part->first_offset = part->root_offset + (part->root_entries * sizeof(struct fat_directory_entry)) / part->sector_size;
+    part->cluster_size = fat12_read_u8(part->sector_buffer + 0x0d);
+
+    uint32_t bytes = (part->sector_count - part->first_offset) * part->sector_size;
+    part->cluster_count = bytes / part->sector_size / part->cluster_size;
+    part->cluster_bytes = (part->cluster_count * 3) / 2;
+
+#ifdef DEBUG
+    ///
+    fprintf(stderr, "part->sector_size: %d\n", part->sector_size);
+
+    // These are in single-unit quantities
+    fprintf(stderr, "part->root_entries: %d\n", part->root_entries);
+    fprintf(stderr, "part->sector_count: %d\n", part->sector_count);
+
+    // These units are "sectors"
+    fprintf(stderr, "part->fat_offset: %d\n", part->fat_offset);
+    fprintf(stderr, "part->fat_size: %d\n", part->fat_size);
+    fprintf(stderr, "part->root_offset: %d\n", part->root_offset);
+    fprintf(stderr, "part->first_offset: %d\n", part->first_offset);
+    fprintf(stderr, "part->cluster_size: %d\n", part->cluster_size);
+
+    fprintf(stderr, "part->cluster_count: %d\n", part->cluster_count);
+    fprintf(stderr, "part->cluster_bytes: %d\n", part->cluster_bytes);
+    fprintf(stderr, "data_bytes: %d\n", bytes);
+    ///
+#endif // DEBUG
+
+    if (1)
+    {
+        part->fat = malloc(part->fat_size * part->sector_size);
+        part->taf = malloc(part->cluster_count * sizeof(uint16_t));
+        fat12_reload(part);
+    }
+
+    return 0;
+}
+
 void fat12_flush(struct fat12_partition *part)
 {
     pang_write(part->io, part->fat_offset * part->sector_size, part->fat, part->fat_size * part->sector_size);
@@ -282,7 +329,7 @@ void fat12_free(struct fat12_partition **part)
     *part = NULL;
 }
 
-static uint32_t fat12_find_free_cluster(struct fat12_partition *part, uint32_t start)
+uint32_t fat12_find_free_cluster(struct fat12_partition *part, uint32_t start)
 {
     uint32_t cluster_value;
     if (start < 1)
@@ -290,12 +337,92 @@ static uint32_t fat12_find_free_cluster(struct fat12_partition *part, uint32_t s
     do
     {
         cluster_value = fat12_get_cluster(part->fat, ++start);
-        fprintf(stderr, "Cluster %d value: %03x\n", start, cluster_value);
+        // fprintf(stderr, "Cluster %d value: %03x\n", start, cluster_value);
     } while (cluster_value != 0);
-    fprintf(stderr, "Found free cluster %d\n", start);
+    // fprintf(stderr, "Found free cluster %d\n", start);
     return start;
 }
 
+static int get_next_directory_sector(struct fat12_partition *part, int depth, int sector)
+{
+    uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
+    if (depth == 0)
+    {
+        if ((part->root_offset - sector) * entries_per_sector >= part->root_entries)
+            return -1;
+        return sector + 1;
+    }
+    uint32_t cluster = cluster_for_sector(part, sector) + 2;
+    if (((sector + 1) & ((part->cluster_size * part->sector_size) - 1)) == (sector + 1))
+    {
+        uint32_t next_cluster = fat12_get_cluster(part->fat, cluster);
+        if (next_cluster >= 0xff8 || next_cluster == 0)
+            return -1;
+        return sector_for_cluster(part, next_cluster);
+    }
+    return sector + 1;
+}
+
+static int find_object(struct fat12_partition *part, const char *filename[], uint32_t prune, struct fat_dirent_ptr *ptr)
+{
+    uint32_t file_cluster = 0;
+    uint32_t depth = 0;
+
+    // Find the dirent of the file
+    uint32_t dirent_cluster = 0;
+
+    // Filename we're searching for
+    struct fat_directory_entry dirent;
+    uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
+    struct fat_directory_entry entries[entries_per_sector];
+
+    // If the root directory matches, take that.
+    int sector = part->root_offset;
+    if (!filename[prune]) {
+        memset(&ptr->entry, 0, sizeof(ptr->entry));
+        ptr->sector = sector;
+        ptr->offset = 0;
+        return 0;
+    }
+
+next_entry:
+    fat_dirent_set_name(&dirent, filename[depth]);
+    int i = 0;
+    int check_entry_i;
+    do
+    {
+        pang_read(part->io, sector * part->sector_size, entries, sizeof(entries));
+        for (check_entry_i = 0; (check_entry_i < entries_per_sector) && (i < part->root_entries); check_entry_i++, i++)
+        {
+            if (!memcmp(&entries[check_entry_i], &dirent, 11))
+            {
+                if (filename[depth + 1 + prune])
+                {
+                    depth++;
+                    sector = fat12_read_u16(entries[check_entry_i].first_cluster) * part->cluster_size + part->first_offset;
+                    goto next_entry;
+                }
+                ptr->entry = entries[check_entry_i];
+                ptr->offset = check_entry_i;
+                ptr->sector = sector;
+                return 0;
+            }
+        }
+    } while ((sector = get_next_directory_sector(part, depth, sector)) != -1);
+    // ENOTFOUND
+    return -1;
+}
+
+static int find_file(struct fat12_partition *part, const char *filename[], struct fat_dirent_ptr *ptr)
+{
+    return find_object(part, filename, 0, ptr);
+}
+
+static int find_parent(struct fat12_partition *part, const char *filename[], struct fat_dirent_ptr *ptr)
+{
+    return find_object(part, filename, 1, ptr);
+}
+
 static int fat12_add_dirent_sector(struct fat12_partition *part, uint32_t sector, uint32_t count, const struct fat_directory_entry *new_dirent)
 {
 
@@ -323,7 +450,7 @@ static int fat12_add_dirent_sector(struct fat12_partition *part, uint32_t sector
     return -1;
 }
 
-static int fat12_dir_update_or_add_dirent(struct fat12_partition *part, uint32_t dir_cluster, const struct fat_directory_entry *dirent)
+static int fat12_dir_update_or_add_dirent(struct fat12_partition *part, uint32_t sector, const struct fat_directory_entry *dirent)
 {
     if (1)
     {
@@ -345,53 +472,33 @@ static int fat12_dir_update_or_add_dirent(struct fat12_partition *part, uint32_t
     return 0;
 }
 
-static void fat_dirent_set_name(struct fat_directory_entry *dirent, const char *filename)
+int fat12_write_file(struct fat12_partition *part, const char *path[], const void *bfr, uint32_t size)
-{
-    int i;
-    int ext_split = -1;
-    int name_off = 0;
-    int dirent_off = 0;
-
-    for (name_off = 0; filename[name_off] != '\0'; name_off++)
-    {
-        if (filename[name_off] == '.')
-            ext_split = name_off + 1;
-    }
-
-    for (dirent_off = 0; dirent_off < 8; dirent_off++)
-    {
-        if (dirent_off < (ext_split - 1))
-            dirent->file_name[dirent_off] = toupper(filename[dirent_off]);
-        else
-            dirent->file_name[dirent_off] = ' ';
-    }
-
-    name_off = ext_split + 1;
-    for (dirent_off = 0; dirent_off < 3; dirent_off++)
-    {
-        if ((ext_split >= 0) && (filename[ext_split]))
-            dirent->extension[dirent_off] = toupper(filename[ext_split++]);
-        else
-            dirent->extension[dirent_off] = ' ';
-    }
-}
-
-int fat12_write_file(struct fat12_partition *part, const char *filename, const void *bfr, uint32_t size)
 {
     // TODO: directory support
     uint32_t first_cluster;
     uint32_t cluster;
+    const char *filename;
+    int i;
+    for (i = 0; path[i+1]; i++)
+        ;
+    filename = path[i];
+
+    struct fat_dirent_ptr parent;
+    if (-1 == find_parent(part, path, &parent)) {
+        // ENOTFOUND
+        return -1;
+    }
 
     cluster = first_cluster = fat12_find_free_cluster(part, 1);
 
     struct fat_directory_entry dirent;
     memset(&dirent, 0, sizeof(dirent));
     fat_dirent_set_name(&dirent, filename);
-    dirent.file_attributes = 0x20;
+    dirent.file_attributes = FAT_ATTR_FILE;
     dirent.reserved1 = 0x18;
     fat12_write_u16(dirent.first_cluster, first_cluster);
     fat12_write_u32(dirent.file_size, size);
-    fat12_dir_update_or_add_dirent(part, 0, &dirent);
+    fat12_dir_update_or_add_dirent(part, parent.sector, &dirent);
 
     while (size > 0)
     {
@@ -404,7 +511,7 @@ int fat12_write_file(struct fat12_partition *part, const char *filename, const v
                    bfr,
                    bytes_to_write);
         size -= bytes_to_write;
-        fprintf(stderr, "%s: %d bytes left\n", filename, size);
+        // fprintf(stderr, "%s: %d bytes left\n", filename, size);
         if (!size)
             fat12_set_cluster(part->fat, cluster, 0xff8);
         else
@@ -416,49 +523,13 @@ int fat12_write_file(struct fat12_partition *part, const char *filename, const v
     }
 }
 
-static uint32_t find_root_cluster_for_file(struct fat12_partition *part, const char *filename)
+int fat12_delete_file(struct fat12_partition *part, const char *filename[])
-{
-    uint32_t file_cluster = 0;
-
-    // Find the dirent of the file
-    uint32_t dirent_cluster = 0;
-
-    // TODO: Support directories other than the root directory
-    if (1)
-    {
-        struct fat_directory_entry dirent;
-        uint32_t entries_per_sector = part->sector_size / sizeof(struct fat_directory_entry);
-        fat_dirent_set_name(&dirent, filename);
-        int i = 0;
-        int check_entry_i;
-        int sector = part->root_offset - 1; // -1 because we use it to update the entry below.
-        while (i < part->root_entries)
-        {
-            struct fat_directory_entry entries[entries_per_sector];
-            pang_read(part->io, ++sector * part->sector_size, entries, sizeof(entries));
-            for (check_entry_i = 0; (check_entry_i < entries_per_sector) && (i < part->root_entries); check_entry_i++, i++)
-            {
-                if (!memcmp(&entries[check_entry_i], &dirent, 11))
-                {
-                    entries[check_entry_i].file_name[0] = 0xe5;
-                    pang_write(part->io, sector * part->sector_size, entries, sizeof(entries));
-                    return fat12_read_u16(entries[check_entry_i].first_cluster);
-                }
-            }
-        }
-    }
-    return 0;
-}
-
-int fat12_delete_file(struct fat12_partition *part, const char *filename)
 {
     // Find the root cluster of the file
-    uint32_t root_cluster = find_root_cluster_for_file(part, filename);
+    struct fat_dirent_ptr ptr;
-
+    if (-1 == find_file(part, filename, &ptr))
-    // A return value of 0 (or 1) is not a valid cluster, so there's
-    // nothing to do.
-    if (root_cluster < 2)
     {
+        fprintf(stderr, "Couldn't find filename %s\n", filename[0]);
         return 0;
     }
 
@@ -466,7 +537,7 @@ int fat12_delete_file(struct fat12_partition *part, const char *filename)
     // it's been deleted.
 
     // Set all clusters in the FAT to 0x000, indicating they're free.
-    uint32_t this_cluster = root_cluster;
+    uint32_t this_cluster = fat12_read_u16(ptr.entry.first_cluster);
     do
     {
         uint32_t next_cluster = fat12_get_cluster(part->fat, this_cluster);
@@ -474,5 +545,52 @@ int fat12_delete_file(struct fat12_partition *part, const char *filename)
         fat12_set_cluster(part->fat, this_cluster, 0);
         this_cluster = next_cluster;
     } while ((this_cluster < 0xff8) && (this_cluster > 1));
+
+    // Free the file by setting the first letter of the filename to 0xe5.
+    ptr.entry.file_name[0] = 0xe5;
+    struct fat_directory_entry full_dir[part->sector_size / sizeof(struct fat_directory_entry)];
+    pang_read(part->io, ptr.sector * part->sector_size, full_dir, part->sector_size);
+    full_dir[ptr.offset] = ptr.entry;
+    pang_write(part->io, ptr.sector * part->sector_size, full_dir, part->sector_size);
+
     return 0;
+}
+
+int fat12_defragment_file(struct fat12_partition *part, const char *path[])
+{
+    struct fat_dirent_ptr ptr;
+    uint32_t cluster;
+    if (-1 == find_file(part, path, &ptr))
+        return -1;
+
+    cluster = cluster_for_sector(part, ptr.sector);
+    while (1) {
+        uint32_t next_cluster = fat12_get_cluster(part->fat, cluster);
+        if ((next_cluster == 0) || (cluster >= 0xff8)) {
+            return 0;
+        }
+        if (next_cluster != cluster + 1) {
+            // File is fragmented!
+            // We need to figure out if it's part of a chain, or if it's the root node.
+            if (fat12_get_cluster(part->fat, cluster + 1) == 0) {
+                // Yay, the cluster is free!  Swap our data into here
+            }
+            else {
+                fprintf(stderr, "Cluster is used by: %04x\n", part->taf[cluster + 1]);
+                /*
+                // The cluster is used.  Figure out if it's in the FAT, or if it's a dirent.
+                uint32_t fat_scan_offset;
+                for (fat_scan_offset = 2; fat_scan_offset < part->cluster_count; fat_scan_offset++) {
+                    if (fat12_get_cluster(part->fat, fat_scan_offset) == (cluster + 1)) {
+                        // Found a match, update the FAT entry and swap our data with the one at this offset.
+                    }
+                }
+                // Didn't find a match, so it must be a directory entry.
+                */
+               exit(1);
+            }
+            
+        }
+        cluster = next_cluster + 1;
+    }
 }

src/mkfat.c

@@ -6,7 +6,9 @@
 #include "fat12-internals.h"
 #include "io.h"
 
+#ifdef DEBUG
 #include <stdio.h>
+#endif
 
 // Create a FAT12 filesystem using the given file descriptor,
 // with length _bytes_.
@@ -33,6 +35,7 @@ int fat12_mkfs(struct pang_io *io, uint32_t bytes) {
         root_directory_sector_count = cluster_size;
     uint32_t root_directory_entry_count = (sector_size / sizeof(struct fat_directory_entry)) * root_directory_sector_count;
 
+#ifdef DEBUG
     fprintf(stderr, "bytes: %d\n", bytes);
     fprintf(stderr, "sector_size: %d\n", sector_size);
     fprintf(stderr, "cluster_size: %d\n", cluster_size);
@@ -42,6 +45,7 @@ int fat12_mkfs(struct pang_io *io, uint32_t bytes) {
     fprintf(stderr, "root_directory_sector_count: %d\n", root_directory_sector_count);
     fprintf(stderr, "root_directory_entry_count: %d\n", root_directory_entry_count);
     fprintf(stderr, "\n");
+#endif
 
     memset(mbr, 0, sizeof(mbr));
 

tests/fragment-file.c

@@ -73,25 +73,30 @@ int main(int argc, char **argv)
         return 1;
     }
 
+    const char *foo_filename[] = { "foo.bar", NULL };
+    const char *baz_filename[] = { "baz.qux", NULL };
+
     memset_str(tmp_bfr, "baz.qux\x0a", 16384);
-    fat12_write_file(part, "baz.qux", tmp_bfr, 16384);
+    fat12_write_file(part, baz_filename, tmp_bfr, 16384);
     // run_command("yes baz.qux | dd bs=16384 count=1 | fattool build/fat12-fragmented.img writefile baz.qux");
 
     memset_str(tmp_bfr, "foo.bar\x0a", 16384);
-    fat12_write_file(part, "foo.bar", tmp_bfr, 16384);
+    fat12_write_file(part, foo_filename, tmp_bfr, 16384);
     // run_command("yes foo.bar | dd bs=16384 count=1 | fattool build/fat12-fragmented.img writefile foo.bar");
 
-    fat12_delete_file(part, "baz.qux");
+    fat12_delete_file(part, baz_filename);
     // fat12_flush(part);
     // run_command("fattool build/fat12-fragmented.img deletefile baz.qux");
     // fat12_sync(part);
 
     memset_str(tmp_bfr, "baz.qux\x0a", 32768);
-    fat12_write_file(part, "baz.qux", tmp_bfr, 32768);
+    fat12_write_file(part, baz_filename, tmp_bfr, 32768);
     // run_command("yes baz.qux | dd bs=16384 count=2 | fattool build/fat12-fragmented.img writefile baz.qux");
 
     fat12_ls_foreach(part, 0, NULL, list_directory);
 
+    fat12_defragment_file(part, baz_filename);//const char *path[])
+
     fat12_close(part);
     fat12_free(&part);