Syslinux - Nov 2008 - [PATCH 1/1] COMBOOT API: Add get current working directory call to most

From: Gene Cumm <gene.cumm at gmail.com>

COMBOOT API: Add get current working directory call to most

Signed-off-by: Gene Cumm <gene.cumm at gmail.com>

---

Adds an API call to obtain the current working directory.  EXTLINUX
will not return the correct value yet however SYSLINUX, ISOLINUX, and
PXELINUX will return the correct value.  For the moment, EXTLINUX will
ONLY return "/" (null-terminated of course).  In SYSLINUX and
ISOLINUX, it presets the CurrentDirName string to "/" for safety.
PXELINUX copies TFTP Prefix to CurrentDirName (minus the trailing
"/").

Based on current head.  Conflicts with a previous patch I e-mailed.

diff --git a/core/comboot.inc b/core/comboot.inc
index 810d825..bdc43ba 100644
--- a/core/comboot.inc
+++ b/core/comboot.inc
@@ -1033,6 +1033,14 @@ comapi_getadv:
 ;
 comapi_writeadv	equ adv_write

+;
+; INT 22h AX=001Eh	Get current working directory
+;
+comapi_getcwd	mov P_ES,cs
+		mov P_BX,CurrentDirName
+		clc
+		ret
+
 		section .data

 %macro		int21 2
@@ -1085,6 +1093,7 @@ int22_table:
 		dw comapi_shufflerm	; 001B cleanup, shuffle and boot to rm
 		dw comapi_getadv	; 001C get pointer to ADV
 		dw comapi_writeadv	; 001D write ADV to disk
+		dw comapi_getcwd	; 001E get current working directory
 int22_count	equ ($-int22_table)/2

 APIKeyWait	db 0
@@ -1109,3 +1118,4 @@ err_comlarge	db 'COMBOOT image too large.', CR,
LF, 0
 		alignb 4
 DOSErrTramp	resd	33		; Error trampolines
 ConfigName	resb	FILENAME_MAX
+CurrentDirName	resb	FILENAME_MAX
diff --git a/core/extlinux.asm b/core/extlinux.asm
index 24d0d92..c9ec166 100644
--- a/core/extlinux.asm
+++ b/core/extlinux.asm
@@ -42,6 +42,8 @@ MAX_SYMLINKS	equ 64			; Maximum number of symlinks per lookup
 SYMLINK_SECTORS	equ 2			; Max number of sectors in a symlink
 					; (should be >= FILENAME_MAX)

+ROOT_DIR_WORD	equ 0x002F
+
 ;
 ; This is what we need to do when idle
 ;
@@ -843,6 +845,8 @@ load_config:
 		mov si,config_name	; Save config file name
 		mov di,ConfigName
 		call strcpy
+		mov word[CurrentDirName], ROOT_DIR_WORD	; Write '/',0 to the
CurrentDirName
+		call build_curdir_str

 		mov di,ConfigName
 		call open
@@ -1515,6 +1519,9 @@ getfssec:
 		pop ebp
 		ret

+build_curdir_str:
+		ret
+
 ; -----------------------------------------------------------------------------
 ;  Common modules
 ; -----------------------------------------------------------------------------
diff --git a/core/isolinux.asm b/core/isolinux.asm
index 3b97005..fbd1ba0 100644
--- a/core/isolinux.asm
+++ b/core/isolinux.asm
@@ -36,6 +36,8 @@ MAX_OPEN	equ (1 << MAX_OPEN_LG2)
 SECTOR_SHIFT	equ 11			; 2048 bytes/sector (El Torito requirement)
 SECTOR_SIZE	equ (1 << SECTOR_SHIFT)

+ROOT_DIR_WORD	equ 0x002F
+
 ;
 ; This is what we need to do when idle
 ;
@@ -1147,15 +1149,30 @@ get_fs_structures:
 		; Look for an isolinux directory, and if found,
 		; make it the current directory instead of the root
 		; directory.
+		; Also copy the name of the directory to CurrentDirName
+		mov word[CurrentDirName], ROOT_DIR_WORD	; Write '/',0 to the
CurrentDirName
 		mov di,boot_dir			; Search for /boot/isolinux
 		mov al,02h
+		push di
 		call searchdir_iso
+		pop di
 		jnz .found_dir
 		mov di,isolinux_dir
 		mov al,02h			; Search for /isolinux
+		push di
 		call searchdir_iso
+		pop di
 		jz .no_isolinux_dir
 .found_dir:
+		; Copy current directory name to CurrentDirName
+		push si
+		push di
+		mov si,di
+		mov di,CurrentDirName
+		call strcpy
+		pop di
+		pop si
+
 		mov [CurrentDir+dir_len],eax
 		mov eax,[si+file_left]
 		mov [CurrentDir+dir_clust],eax
diff --git a/core/ldlinux.asm b/core/ldlinux.asm
index c7f6577..75e8fef 100644
--- a/core/ldlinux.asm
+++ b/core/ldlinux.asm
@@ -44,6 +44,8 @@ MAX_OPEN	equ (1 << MAX_OPEN_LG2)
 SECTOR_SHIFT	equ 9
 SECTOR_SIZE	equ (1 << SECTOR_SHIFT)

+ROOT_DIR_WORD	equ 0x002F
+
 ;
 ; This is what we need to do when idle
 ;
@@ -900,19 +902,40 @@ getfattype:
 		mov si,config_name	; Save configuration file name
 		mov di,ConfigName
 		call strcpy
+		mov word[CurrentDirName], ROOT_DIR_WORD	; Write '/',0 to the
CurrentDirName

 		mov eax,[RootDir]	; Make the root directory ...
 		mov [CurrentDir],eax	; ... the current directory
 		mov di,syslinux_cfg1
+		push di
 		call open
+		pop di
 		jnz .config_open
 		mov di,syslinux_cfg2
+		push di
 		call open
+		pop di
 		jnz .config_open
 		mov di,syslinux_cfg3
+		push di
 		call open
+		pop di
 		jz no_config_file
 .config_open:
+		push si
+		mov si,di
+		push si
+		mov di,CurrentDirName
+			; This is inefficient as it will copy more than needed
+			;   but not by too much
+		call strcpy
+		mov ax,syslinux_cfg3	;Cut it down
+		pop si
+		sub ax,si
+		mov di,CurrentDirName
+		add di,ax
+		mov byte[di],0
+		pop si
 		mov eax,[PrevDir]	; Make the directory with syslinux.cfg ...
 		mov [CurrentDir],eax	; ... the current directory

diff --git a/core/pxelinux.asm b/core/pxelinux.asm
index 4398582..95c5bee 100644
--- a/core/pxelinux.asm
+++ b/core/pxelinux.asm
@@ -704,6 +704,15 @@ prefix:		test byte [DHCPMagic], 04h	; Did we get
a path prefix option
 		call writestr_early
 		call crlf

+		; Set CurrentDirName
+		push di
+		mov si,PathPrefix
+		mov di,CurrentDirName
+		call strcpy
+		sub di,2
+		mov byte[di],0
+		pop di
+
 ;
 ; Load configuration file
 ;

Gene Cumm wrote:
> From: Gene Cumm <gene.cumm at gmail.com>
> 
> COMBOOT API: Add get current working directory call to most
> 
> Signed-off-by: Gene Cumm <gene.cumm at gmail.com>
> 
> ---
> 
> Adds an API call to obtain the current working directory.  EXTLINUX
> will not return the correct value yet however SYSLINUX, ISOLINUX, and
> PXELINUX will return the correct value.  For the moment, EXTLINUX will
> ONLY return "/" (null-terminated of course).  In SYSLINUX and
> ISOLINUX, it presets the CurrentDirName string to "/" for safety.
> PXELINUX copies TFTP Prefix to CurrentDirName (minus the trailing
> "/").
> 
Okay, this isn't quite right, especially in the case of the TFTP prefix;
the TFTP prefix may not end in '/', especially when the TFTP server is
not a Unix system.  Therefore I think this call should return a prefix
(including a final '/' in case of the filesystem-based variants.)

	-hpa

On Sun, Nov 9, 2008 at 7:22 PM, Gene Cumm <gene.cumm at gmail.com>
wrote:
> From: Gene Cumm <gene.cumm at gmail.com>
>
> COMBOOT API: Add get current working directory call to most
>
> Signed-off-by: Gene Cumm <gene.cumm at gmail.com>
>
> ---
>
> Adds an API call to obtain the current working directory.  EXTLINUX
> will not return the correct value yet however SYSLINUX, ISOLINUX, and
> PXELINUX will return the correct value.  For the moment, EXTLINUX will
> ONLY return "/" (null-terminated of course).  In SYSLINUX and
> ISOLINUX, it presets the CurrentDirName string to "/" for safety.
> PXELINUX copies TFTP Prefix to CurrentDirName (minus the trailing
> "/").
>
> Based on current head.  Conflicts with a previous patch I e-mailed.
Completing the implementation within EXTLINUX will require examining
how to recurse up a directory tree, obtaining the name of each
directory and then return building the current directory string.  It
might have been possible to cheat and let the installer pre-populate
it (like the INODE number is stored) however moving the directory
containing extlinux.sys to become another path (ie from /boot/extlinux
to /extlinux) won't change the INODE number (at least the one time I
tested) but would invalidate the original stored path.