Make syslinux installer real "pathbased"

The previous merging extlinux/syslinux patch is not sufficient, the
syslinux is not real "patchbased", hence:

* fill currentdir in patcharea
* search "extlinux.conf" and "syslinux.cfg" for generic_load_config
* define boot_image and boot_sector macro for ldsyslinux
  this could make further merging extlinux and syslinux possible

Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

8 files changed, 43 insertions, 22 deletions

diff --git a/core/fs/fat/fat.c b/core/fs/fat/fat.c
index a21f4312..9877a4d5 100644
--- a/core/fs/fat/fat.c
+++ b/core/fs/fat/fat.c
@@ -708,7 +708,7 @@ static int vfat_load_config(void)
     com32sys_t regs;
     int i;
 
-    /* If installed by extlinux, try the extlinux filename */
+    /* If path filled by installer, then use that to load config*/
     if (*CurrentDirName && !generic_load_config())
 	return 0;
 
diff --git a/core/fs/lib/loadconfig.c b/core/fs/lib/loadconfig.c
index 9318c1c3..d84bdef9 100644
--- a/core/fs/lib/loadconfig.c
+++ b/core/fs/lib/loadconfig.c
@@ -5,20 +5,26 @@
 #include <fs.h>
 
 /*
- * Standard version of load_config for extlinux-installed filesystems
+ * Standard version of load_config for extlinux/syslinux filesystems
  */
 int generic_load_config(void)
 {
     com32sys_t regs;
 
     chdir(CurrentDirName);
+    /* try extlinux.conf first */
     realpath(ConfigName, "extlinux.conf", FILENAME_MAX);
-
-    dprintf("Config = %s\n", ConfigName);
-
+    dprintf("Try config = %s\n", ConfigName);
     memset(&regs, 0, sizeof regs);
     regs.edi.w[0] = OFFS_WRT(ConfigName, 0);
     call16(core_open, &regs, &regs);
-
+    /* give syslinux.cfg a chance ? */
+    if (regs.eflags.l & EFLAGS_ZF) {
+	realpath(ConfigName, "syslinux.cfg", FILENAME_MAX);
+	dprintf("Then try config = %s\n", ConfigName);
+	memset(&regs, 0, sizeof regs);
+	regs.edi.w[0] = OFFS_WRT(ConfigName, 0);
+	call16(core_open, &regs, &regs);
+    }
     return (regs.eflags.l & EFLAGS_ZF) ? -1 : 0;
 }
diff --git a/dos/syslinux.c b/dos/syslinux.c
index 61020a1f..94517e8f 100644
--- a/dos/syslinux.c
+++ b/dos/syslinux.c
@@ -755,7 +755,7 @@ int main(int argc, char *argv[])
     /*
      * Patch ldlinux.sys and the boot sector
      */
-    i = syslinux_patch(sectors, nsectors, stupid, raid_mode);
+    i = syslinux_patch(sectors, nsectors, stupid, raid_mode, subdir);
     patch_sectors = (i + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 
     /*
diff --git a/libinstaller/syslinux.h b/libinstaller/syslinux.h
index 8d0212c8..311b9f2e 100644
--- a/libinstaller/syslinux.h
+++ b/libinstaller/syslinux.h
@@ -26,6 +26,11 @@ extern unsigned char syslinux_ldlinux[];
 extern const unsigned int syslinux_ldlinux_len;
 extern const int syslinux_ldlinux_mtime;
 
+#define boot_sector	syslinux_bootsect
+#define boot_sector_len syslinux_bootsect_len
+#define boot_image	syslinux_ldlinux
+#define boot_image_len	syslinux_ldlinux_len
+
 extern unsigned char syslinux_mbr[];
 extern const unsigned int syslinux_mbr_len;
 extern const int syslinux_mbr_mtime;
@@ -42,6 +47,6 @@ const char *syslinux_check_bootsect(const void *bs);
 
 /* This patches the boot sector and ldlinux.sys based on a sector map */
 int syslinux_patch(const uint32_t * sectors, int nsectors,
-		   int stupid, int raid_mode);
+		   int stupid, int raid_mode, const char *subdir);
 
 #endif
diff --git a/libinstaller/syslxmod.c b/libinstaller/syslxmod.c
index 9ab139c6..b28a443b 100644
--- a/libinstaller/syslxmod.c
+++ b/libinstaller/syslxmod.c
@@ -29,7 +29,7 @@ void syslinux_make_bootsect(void *bs)
 {
     struct boot_sector *bootsect = bs;
     const struct boot_sector *sbs =
-	(const struct boot_sector *)syslinux_bootsect;
+	(const struct boot_sector *)boot_sector;
 
     memcpy(&bootsect->bsHead, &sbs->bsHead, bsHeadLen);
     memcpy(&bootsect->bsCode, &sbs->bsCode, bsCodeLen);
@@ -227,14 +227,15 @@ static __noinline void set_32_sl(uint32_t * p, uint32_t v)
  * otherwise -1.
  */
 int syslinux_patch(const uint32_t * sectors, int nsectors,
-		   int stupid, int raid_mode)
+		   int stupid, int raid_mode, const char *subdir)
 {
     struct patch_area *patcharea;
     uint32_t *wp;
-    int nsect = (syslinux_ldlinux_len + 511) >> 9;
+    int nsect = (boot_image_len + 511) >> 9;
     uint32_t csum;
     int i, dw, nptrs, rv;
-    struct boot_sector *sbs = (struct boot_sector *)syslinux_bootsect;
+    struct boot_sector *sbs = (struct boot_sector *)boot_sector;
+    int diroffset, dirlen;
 
     if (nsectors < nsect)
 	return -1;
@@ -254,18 +255,29 @@ int syslinux_patch(const uint32_t * sectors, int nsectors,
     set_32(&sbs->NextSector, *sectors++);
 
     /* Search for LDLINUX_MAGIC to find the patch area */
-    for (wp = (uint32_t *) syslinux_ldlinux; get_32_sl(wp) != LDLINUX_MAGIC;
+    for (wp = (uint32_t *)boot_image; get_32_sl(wp) != LDLINUX_MAGIC;
 	 wp++) ;
     patcharea = (struct patch_area *)wp;
 
     /* Set up the totals */
-    dw = syslinux_ldlinux_len >> 2;	/* COMPLETE dwords, excluding ADV */
+    dw = boot_image_len >> 2;	/* COMPLETE dwords, excluding ADV */
     set_16_sl(&patcharea->data_sectors, nsect);	/* Not including ADVs */
     set_16_sl(&patcharea->adv_sectors, 2);	/* ADVs need 2 sectors */
     set_32_sl(&patcharea->dwords, dw);
 
+    /* Poke in the base directory path */
+    if (subdir) {
+	diroffset = get_16(&patcharea->diroffset);
+	dirlen = get_16(&patcharea->dirlen);
+	if (dirlen <= strlen(subdir)) {
+	    fprintf(stderr, "Subdirectory path too long... aborting install!\n");
+	    exit(1);
+	}
+	memcpy((char *)boot_image + diroffset, subdir, strlen(subdir) + 1);
+    }
+
     /* Set the sector pointers */
-    wp = (uint32_t *) ((char *)syslinux_ldlinux +
+    wp = (uint32_t *) ((char *)boot_image +
 		       get_16_sl(&patcharea->secptroffset));
     nptrs = get_16_sl(&patcharea->secptrcnt);
 
@@ -277,16 +289,14 @@ int syslinux_patch(const uint32_t * sectors, int nsectors,
     while (nptrs--)
 	set_32_sl(wp++, 0);
 
-    rv = (char *)wp - (char *)syslinux_ldlinux;
-
     /* Now produce a checksum */
     set_32_sl(&patcharea->checksum, 0);
 
     csum = LDLINUX_MAGIC;
-    for (i = 0, wp = (uint32_t *) syslinux_ldlinux; i < dw; i++, wp++)
+    for (i = 0, wp = (uint32_t *)boot_image; i < dw; i++, wp++)
 	csum -= get_32_sl(wp);	/* Negative checksum */
 
     set_32_sl(&patcharea->checksum, csum);
 
-    return rv;
+    return dw << 2;
 }
diff --git a/linux/syslinux.c b/linux/syslinux.c
index 3032edce..1194fbb3 100644
--- a/linux/syslinux.c
+++ b/linux/syslinux.c
@@ -465,7 +465,7 @@ umount:
     /*
      * Patch ldlinux.sys and the boot sector
      */
-    i = syslinux_patch(sectors, ldlinux_sectors, opt.stupid_mode, opt.raid_mode);
+    i = syslinux_patch(sectors, ldlinux_sectors, opt.stupid_mode, opt.raid_mode, subdir);
     patch_sectors = (i + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 
     /*
diff --git a/mtools/syslinux.c b/mtools/syslinux.c
index 2c5387ed..2b82b33e 100644
--- a/mtools/syslinux.c
+++ b/mtools/syslinux.c
@@ -267,7 +267,7 @@ int main(int argc, char *argv[])
     libfat_close(fs);
 
     /* Patch ldlinux.sys and the boot sector */
-    i = syslinux_patch(sectors, nsectors, stupid, raid_mode);
+    i = syslinux_patch(sectors, nsectors, stupid, raid_mode, subdir);
     patch_sectors = (i + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 
     /* Write the now-patched first sectors of ldlinux.sys */
diff --git a/win32/syslinux.c b/win32/syslinux.c
index d8c6c82b..bd042739 100644
--- a/win32/syslinux.c
+++ b/win32/syslinux.c
@@ -433,7 +433,7 @@ int main(int argc, char *argv[])
     /*
      * Patch ldlinux.sys and the boot sector
      */
-    syslinux_patch(sectors, nsectors, stupid, raid_mode);
+    syslinux_patch(sectors, nsectors, stupid, raid_mode, subdir);
 
     /*
      * Rewrite the file