| 0,0 → 1,154 |
|---|
| /* Superblock support. */ |
| |
| /* Methods: |
| * init_super: initializes the superblock structure for later use |
| * get_super: return pointer at the superblock |
| * read_super: read a superblock |
| */ |
| |
| #include <string.h> |
| #include "fs.h" |
| #include "block.h" |
| #include "inode.h" |
| #include "super.h" |
| #include <stdio.h> |
| |
| |
| super_block_t* super_block; |
| |
| static int v1(int magic, int *version, int *extend); |
| static int v2(int magic ,int*version, int *extend); |
| static int get_native(int magic, int *version, int *extend); |
| |
| int (*versions[TOTAL_VERSIONS])(int , int*, int*) = { |
| v1, /* 0 = V1 version */ |
| v2 /* 1 = V2 version */ |
| }; |
| |
| int init_super_block() |
| { |
| |
| super_block = (super_block_t*)malloc(sizeof(super_block_t)); |
| if (super_block != NULL) |
| return TRUE; |
| |
| return FALSE; |
| } |
| |
| super_block_t *get_super() |
| { |
| return super_block; |
| } |
| |
| int read_super(register super_block_t *sp) |
| { |
| |
| /* Read a superblock. */ |
| |
| register block_t *bp; |
| int magic, version, extend, native; |
| |
| |
| bp = get_block(SUPER_BLOCK); |
| memcpy((void *)sp, (void *)(bp->b.b__data), (size_t)SUPER_SIZE); |
| magic = sp->s_magic; /* determines file system type */ |
| |
| |
| /* Get file system version and type. */ |
| native = get_native(magic, &version, &extend); |
| |
| if (native == FS_EINVAL) { |
| print_console("Unknown version of file system\n"); |
| print_console("Magic is bad\n"); |
| return FS_EINVAL; |
| } |
| |
| /* In V1, the device size was kept in a short, s_nzones, which limited |
| * devices to 32K zones. For V2, it was decided to keep the size as a |
| * long. However, just changing s_nzones to a long would not work, since |
| * then the position of s_magic in the super block would not be the same |
| * in V1 and V2 file systems, and there would be no way to tell whether |
| * a newly mounted file system was V1 or V2. The solution was to introduce |
| * a new variable, s_zones, and copy the size there. |
| * |
| * Calculate some other numbers that depend on the version here too, to |
| * hide some of the differences. |
| */ |
| |
| if (version == V1) { |
| sp->s_zones = sp->s_nzones; /* only V1 needs this copy */ |
| sp->s_inodes_per_block = V1_INODES_PER_BLOCK; |
| sp->s_ndzones = V1_NR_DZONES; |
| sp->s_nindirs = V1_INDIRECTS; |
| } |
| else { |
| sp->s_inodes_per_block = V2_INODES_PER_BLOCK; |
| sp->s_ndzones = V2_NR_DZONES; |
| sp->s_nindirs = V2_INDIRECTS; |
| } |
| |
| sp->s_isearch = 0; /* inode searches initially start at 0 */ |
| sp->s_zsearch = 0; /* zone searches initially start at 0 */ |
| sp->s_version = version; |
| sp->s_native = native; |
| sp->s_extend = extend; |
| |
| |
| /* Make a few basic checks to see if super block looks reasonable. */ |
| if (sp->s_imap_blocks < 1 || sp->s_zmap_blocks < 1 |
| || sp->s_ninodes < 1 || sp->s_zones < 1 |
| || (unsigned) sp->s_log_zone_size > 4) { |
| return FS_EINVAL; |
| } |
| |
| return OK; |
| } |
| |
| int v1(int magic, int* version, int *extend) |
| { |
| |
| if (magic == SUPER_MAGIC || magic == conv2(BYTE_SWAP,SUPER_MAGIC)) { |
| |
| *version = V1; *extend = FALSE; |
| return TRUE; |
| } |
| if (magic == SUPER_MAGIC2 || magic == conv2(BYTE_SWAP,SUPER_MAGIC2)) { |
| *version = V1; *extend = TRUE; |
| return TRUE; |
| } |
| |
| return FALSE; |
| } |
| |
| int v2(int magic, int *version, int *extend) |
| { |
| |
| if (magic == SUPER_V2 || magic == conv2(BYTE_SWAP,SUPER_V2)) { |
| *version = V2; *extend = FALSE; |
| return TRUE; |
| } |
| |
| if (magic == SUPER_V2E || magic == conv2(BYTE_SWAP,SUPER_V2E)) { |
| *version = V2; *extend = TRUE; |
| return TRUE; |
| } |
| |
| return FALSE; |
| } |
| |
| int get_native(int magic, int *version, int *extend) |
| { |
| |
| |
| int i, result; |
| |
| /* Get file system version and type */ |
| for (i = 0; i < TOTAL_VERSIONS; i++) { |
| result = versions[i](magic, version, extend); |
| if (result) { |
| return result; |
| } |
| } |
| |
| return FS_EINVAL; |
| } |