[syslinux] SYSLINUX 3.35 released

[Luciano Miguel Ferreira Rocha]

On Mon, Jan 29, 2007 at 08:19:01AM -0800, H. Peter Anvin wrote:
> Sven Geggus wrote:
> > 
> > Any particular reason, why the directory given with -d is not part of the
> > search sequence?
> > 
> 
> Yes, although one can argue it isn't a *good* reason.
> 
> The reason is that the installer would have to be able to do a 
> VFAT-to-MSDOS transformation on the entire path in order to encode it in 
> ldlinux.sys (encoding something like the starting sector of a directory 
> is unsafe in FAT, since it's not guaranteed to stay put.)

Correct me if I'm wrong, but from reading unix/syslinux.c, the
filesystem is mounted as msdos, ergo no VFAT-to-MSDOS translation is
needed for the -d option, as any "vfat" component on -d will fail upon
the rename.

> 
> Not all environments can do that natively, which means I would have had 
> to write libfat code for it, and that would have made it take a lot longer.

Which ones? Win32?

> 
> In general I consider that a potential future addition.
> 

After battling for a few hours with ldlinux.lst, I ended up having to do
a string search in syslinux_ldlinux for the place I created for the
specified dir.

The attached patch changes ldlinux.asm (adds a syslinux_cfg0 buffer for
the new location) and unix/syslinux.c (set the reserved region to the
specified directory).

I didn't like that I couldn't find the location of the buffer from the
.lst, I'm probably missing something obvious. The length is easy, but is
hardcoded to 32 bytes for now (counting with suffix "/syslinux.cfg"). 64
bytes also works OK.

PS: After some more battles, I can locate the buffer using ldlinux.map:
<location_of_syslinux_cfg0>-<start_of_.text>-<0x200 (a sector)>. Is
there an easy way of getting that and syslinux_cfg1-syslinux_cfg0
without having to use awk/sed/perl?

-- 
lfr
0/0
-------------- next part --------------
diff -ur syslinux-3.35/ldlinux.asm syslinux-3.35.1/ldlinux.asm
--- syslinux-3.35/ldlinux.asm	2007-01-29 01:56:21.000000000 +0000
+++ syslinux-3.35.1/ldlinux.asm	2007-02-02 02:56:12.000000000 +0000
@@ -899,6 +899,10 @@
 ;
 ; Load configuration file
 ;
+
+		mov di,syslinux_cfg0
+		call open
+		jnz .config_open
 		mov di,syslinux_cfg1
 		call open
 		jnz .config_open
@@ -1583,6 +1587,7 @@
 crlf_msg	db CR, LF
 null_msg	db 0
 crff_msg	db CR, FF, 0
+syslinux_cfg0:	times 32 db 0 			; option for -d
 syslinux_cfg1	db '/boot'			; /boot/syslinux/syslinux.cfg
 syslinux_cfg2	db '/syslinux'			; /syslinux/syslinux.cfg
 syslinux_cfg3	db '/'				; /syslinux.cfg
diff -ur syslinux-3.35/unix/syslinux.c syslinux-3.35.1/unix/syslinux.c
--- syslinux-3.35/unix/syslinux.c	2007-01-29 01:56:21.000000000 +0000
+++ syslinux-3.35.1/unix/syslinux.c	2007-02-02 02:45:36.000000000 +0000
@@ -208,6 +208,22 @@
 	  force = 1;		/* Force install */
 	} else if ( *opt == 'd' && argp[1] ) {
 	  subdir = *++argp;
+	  unsigned char *p = (unsigned char *) memmem(syslinux_ldlinux, syslinux_ldlinux_len,
+				  "/boot/syslinux/syslinux.cfg", 27) - 32;
+	  int l = strlen(subdir);
+
+	  int i;
+	  for (i = 0; p[i] == '\0'; i++);
+	  if (i == 32 && (l + 15) < 32) {
+	    /* remove trailing / */
+	    while (subdir[l - 1] == '/') l--;
+
+	    if (subdir[0] != '/') *p++ = '/';
+	    memcpy(p, subdir, l);
+	    strcpy(p + l, "/syslinux.cfg");
+	  } else {
+	    strcpy(p, "/boot/syslinux/syslinux.cfg");
+	  }
 	} else if ( *opt == 'o' && argp[1] ) {
 	  filesystem_offset = (off_t)strtoull(*++argp, NULL, 0); /* Byte offset */
 	} else {