%define EXT2_GOOD_OLD_REV 0 ; The good old (original) format
%define EXT2_DYNAMIC_REV 1 ; V2 format w/ dynamic inode sizes
+%define EXT2_GOOD_OLD_INODE_SIZE 128
+
+; Special inode numbers
+%define EXT2_BAD_INO 1 ; Bad blocks inode
+%define EXT2_ROOT_INO 2 ; Root inode
+%define EXT2_BOOT_LOADER_INO 5 ; Boot loader inode
+%define EXT2_UNDEL_DIR_INO 6 ; Undelete directory inode
+%define EXT3_RESIZE_INO 7 ; Reserved group descriptors inode
+%define EXT3_JOURNAL_INO 8 ; Journal inode
+
+; We're readonly, so we only care about incompat features.
+%define EXT2_FEATURE_INCOMPAT_COMPRESSION 0x0001
+%define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002
+%define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004
+%define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008
+%define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
+%define EXT2_FEATURE_INCOMPAT_ANY 0xffffffff
%define EXT2_NDIR_BLOCKS 12
%define EXT2_IND_BLOCK EXT2_NDIR_BLOCKS
%define ext2_group_desc_lg2size 5
+;
+; Structure definition for ext2 directory entry
+;
+ struc ext2_dir_entry
+d_inode resd 1 ; Inode number
+d_rec_len resw 1 ; Directory entry length
+d_name_len resb 1 ; Name length
+d_file_type resb 1 ; File type
+d_name equ $
+ endstruc
; File structure. This holds the information for each currently open file.
;
struc open_file_t
+file_left resd 1 ; Number of sectors left (0 = free)
file_sector resd 1 ; Next linear sector to read
-file_left resd 1 ; Number of sectors left
file_in_sec resd 1 ; Sector where inode lives
file_in_off resw 1
resw 1
EndSector resd 1 ; Location of filesystem end
ClustSize resd 1 ; Bytes/cluster
ClustMask resd 1 ; Sectors/cluster - 1
-CachePtrs resw 65536/SECTOR_SIZE ; Cached sector pointers
-NextCacheSlot resw 1 ; Next cache slot to occupy
CopySuper resb 1 ; Distinguish .bs versus .bss
DriveNumber resb 1 ; BIOS drive number
ClustShift resb 1 ; Shift count for sectors/cluster
; ZF = 0 if we fell out of the loop
.found: pop cx
ret
+;
+; open_inode:
+; Open a file indicated by an inode number in EAX
+;
+; NOTE: This file considers finding a zero-length file an
+; error. This is so we don't have to deal with that special
+; case elsewhere in the program (most loops have the test
+; at the end).
+;
+; If successful:
+; ZF clear
+; SI = file pointer
+; DX:AX = EAX = file length in bytes
+; If unsuccessful
+; ZF set
+;
+open_inode.allocate_failure:
+ xor eax,eax
+ ret
+
+open_inode:
+ call allocate_file
+ jnz .allocate_failure
+
+ push gs
+ ; First, get the appropriate inode group and index
+ dec eax ; There is no inode 0
+ xor edx,edx
+ mov [bx+file_sector],edx
+ div dword [SuperBlock+s_inodes_per_group]
+ ; EAX = inode group; EDX = inode within group
+ push edx
+
+ ; Now, we need the block group descriptor.
+ ; To get that, we first need the relevant descriptor block.
+
+ shl eax, ext2_group_desc_lg2size ; Get byte offset in desc table
+ xor edx,edx
+ div dword [BlockSize]
+ ; eax = block #, edx = offset in block
+ add eax,dword [SuperBlock+s_first_data_block]
+ inc eax ; s_first_data_block+1
+ mov cl,[ClustShift]
+ shl eax,cl
+ call getcachesec ; Get the group descriptor
+ add si,dx
+ mov esi,[gs:si+bg_inode_table] ; Get inode table block #
+ pop eax ; Get inode within group
+ movzx edx, word [SuperBlock+s_inode_size]
+ mul edx
+ ; edx:eax = byte offset in inode table
+ div dword [BlockSize]
+ ; eax = block # versus inode table, edx = offset in block
+ add eax,esi
+ shl eax,cl ; Turn into sector
+ push dx
+ shr edx,SECTOR_SHIFT
+ add eax,edx
+ mov [bx+file_in_sec],eax
+ pop dx
+ and dx,SECTOR_SIZE-1
+ mov [bx+file_in_off],dx
+
+ call getcachesec
+ add si,dx
+ mov eax,[gs:si+i_size]
+ push eax
+ add eax,SECTOR_SIZE-1
+ shr eax,SECTOR_SHIFT
+ mov [bx+file_left],eax
+ pop eax
+ mov si,bx
+ mov edx,eax
+ shr edx,16 ; 16-bitism, sigh
+ and eax,eax ; ZF clear unless zero-length file
+ pop gs
+ ret
+
+;
+; close:
+; Deallocates a file structure (pointer in SI)
+; Assumes CS == DS.
+;
+close:
+ mov dword [si],0 ; First dword == file_left
+ ret
;
; searchdir:
;
; If successful:
; ZF clear
-; SI = file pointer
-; DX:AX = file length in bytes
+; SI = file pointer
+; DX:AX = EAX = file length in bytes
; If unsuccessful
; ZF set
;
-
+; Assumes CS == DS == ES; *** IS THIS CORRECT ***?
+;
searchdir:
- call allocate_file
- jnz .alloc_failure
+ mov eax,[CurrentDir]
+.leadingslash:
+ cmp byte [di],'/' ; Absolute filename?
+ jne .searchloop
+ mov eax,EXT2_ROOT_INO
+ inc di ; Skip slash
+
+.searchloop:
+ ; At this point, EAX contains the directory inode,
+ ; and DS:DI contains a pathname tail.
+ call open_inode
+
+.readdir:
+ mov bx,trackbuf
+ push bx
+ mov cx,[SecPerBlock]
+ call getfssec
+ pop bx
+ pushf ; Save EOF flag
+.getent:
+ cmp dword [bx+d_inode],0
+ je .endblock
+
+ push di
+ push si
+ mov cx,[bx+d_name_len]
+ lea si,[bx+d_name]
+ repe cmpsb
+ pop si
+ je .maybe
+.nope:
+ pop di
+
+ add bx,[bx+d_rec_len]
+ jmp .getent
+
+.endblock:
+ popf
+ jnc .readdir ; There is more
+.failure:
+ xor eax,eax
+ ret
+.maybe:
+ mov eax,[si+d_inode]
+
+ cmp byte [di],0
+ je .finish ; It's a real file; done
+ cmp byte [di],'/'
+ jne .nope ; False alarm
+
+ ; It's a match, but it's a directory.
+ ; Repeat operation.
+ call close
+ pop si ; Adjust stack (di)
+ pop si ; Adjust stack (flags)
+ inc di ; Skip slash
+ jmp .searchloop
+
+.finish: ; We found it; now we need to open the file
+ call close ; Close directory
+ pop si ; Adjust stack (di)
+ pop si ; Adjust stack (flags)
+ call open_inode
ret
+
+;
+; mangle_name: Mangle a filename pointed to by DS:SI into a buffer pointed
+; to by ES:DI; ends on encountering any whitespace.
+;
+; This verifies that a filename is < FILENAME_MAX characters,
+; doesn't contain whitespace, zero-pads the output buffer,
+; and removes redundant slashes,
+; so "repe cmpsb" can do a compare, and the
+; path-searching routine gets a bit of an easier job.
+;
+; FIX: we may want to support \-escapes here (and this would
+; be the place.)
+;
+mangle_name:
+ push bx
+ xor ax,ax
+ mov cx,FILENAME_MAX-1
+ mov bx,di
+
+.mn_loop:
+ lodsb
+ cmp al,' ' ; If control or space, end
+ jna .mn_end
+ cmp al,ah ; Repeated slash?
+ je .mn_skip
+ xor ah,ah
+ cmp al,'/'
+ jne .mn_ok
+ mov ah,al
+.mn_ok stosb
+.mn_skip: loop .mn_loop
+.mn_end:
+ cmp bx,di ; At the beginning of the buffer?
+ jbe .mn_zero
+ cmp byte [di-1],'/' ; Terminal slash?
+ jne .mn_zero
+.mn_kill: dec di ; If so, remove it
+ inc cx
+ jmp short .mn_end
+.mn_zero:
+ inc cx ; At least one null byte
+ xor ax,ax ; Zero-fill name
+ rep stosb
+ pop bx
+ ret ; Done
+
+;
+; unmangle_name: Does the opposite of mangle_name; converts a DOS-mangled
+; filename to the conventional representation. This is needed
+; for the BOOT_IMAGE= parameter for the kernel.
+; NOTE: A 13-byte buffer is mandatory, even if the string is
+; known to be shorter.
+;
+; DS:SI -> input mangled file name
+; ES:DI -> output buffer
+;
+; On return, DI points to the first byte after the output name,
+; which is set to a null byte.
+;
+unmangle_name: call strcpy
+ dec di ; Point to final null byte
+ ret
+
;
; writechr: Write a single character in AL to the console without
; mangling any registers; handle video pages correctly.
int 19h ; And try once more to boot...
.norge: jmp short .norge ; If int 19h returned; this is the end
-;
-; mangle_name: Mangle a DOS filename pointed to by DS:SI into a buffer pointed
-; to by ES:DI; ends on encountering any whitespace
-;
-
-mangle_name:
- ret
-
-;
-; unmangle_name: Does the opposite of mangle_name; converts a DOS-mangled
-; filename to the conventional representation. This is needed
-; for the BOOT_IMAGE= parameter for the kernel.
-; NOTE: A 13-byte buffer is mandatory, even if the string is
-; known to be shorter.
-;
-; DS:SI -> input mangled file name
-; ES:DI -> output buffer
-;
-; On return, DI points to the first byte after the output name,
-; which is set to a null byte.
-;
-unmangle_name:
- ret
-
;
; linsector: Convert a linear sector index in a file to a linear sector number
%ifdef debug ; This code for debugging only
debug_magic dw 0D00Dh ; Debug code sentinel
%endif
-ScrollAttribute db 07h ; White on black (for text mode)
alignb 4, db 0
BufSafe dw trackbufsize/SECTOR_SIZE ; Clusters we can load into trackbuf
projects / platform / upstream / syslinux.git / commitdiff