[syslinux:master] chain: Implement GPT hand-over protocol as documented

[syslinux-bot for Shao Miller]

Commit-ID:  89b665c55648e2bce662332be5ba60381d9f6cec
Gitweb:     http://syslinux.zytor.com/commit/89b665c55648e2bce662332be5ba60381d9f6cec
Author:     Shao Miller <shao.miller at yrdsb.edu.on.ca>
AuthorDate: Fri, 25 Jun 2010 06:45:07 -0400
Committer:  Shao Miller <shao.miller at yrdsb.edu.on.ca>
CommitDate: Fri, 25 Jun 2010 06:45:07 -0400

chain: Implement GPT hand-over protocol as documented

When a partition was yielded by a GPT partition iterator,
we follow the protocol documented in syslinux/doc/gpt.txt.

Signed-off-by: Shao Miller <shao.miller at yrdsb.edu.on.ca>


---
 NEWS                  |    1 +
 com32/modules/chain.c |   51 ++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 51 insertions(+), 1 deletions(-)

diff --git a/NEWS b/NEWS
index fdf33cf..93b64a6 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ to all derivatives.
 Changes in 4.00:
 	* chain.c32: support booting GPT partitions by index
 	* chain.c32: support booting the Syslinux partition with "fs"
+	* chain.c32: implement gpt.txt hand-over protocol
 Changes in 3.86:
 	* chain.c32: fix chainloading the MBR of a hard disk (broken
 	  in 3.85).
diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index 2652de8..6f3729f 100644
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -1419,6 +1419,53 @@ int main(int argc, char *argv[])
 	ndata++;
     }
 
+    /* Do GPT hand-over, if applicable (as per syslinux/doc/gpt.txt) */
+    if (cur_part && (cur_part->next == next_gpt_part)) {
+	struct part_entry *record;
+	/* Look at the GPT partition */
+	const struct gpt_part *gp = (const struct gpt_part *)
+	    (cur_part->block +
+	     (cur_part->private.gpt.size * cur_part->private.gpt.index));
+	/* Note the partition length */
+	uint64_t lba_count = gp->lba_last - gp->lba_first + 1;
+	/* The length of the hand-over */
+	int synth_size =
+	    sizeof(struct part_entry) + sizeof(uint32_t) +
+	    cur_part->private.gpt.size;
+	/* Will point to the partition record length in the hand-over */
+	uint32_t *plen;
+
+	/* Allocate the hand-over record */
+	record = malloc(synth_size);
+	if (!record) {
+	    error("Could not build GPT hand-over record!\n");
+	    goto bail;
+	}
+	/* Synthesize the record */
+	memset(record, 0, synth_size);
+	record->active_flag = 0x80;
+	record->ostype = 0xED;
+	/* All bits set by default */
+	record->start_lba = ~(uint32_t) 0;
+	record->length = ~(uint32_t) 0;
+	/* If these fit the precision, pass them on */
+	if (cur_part->lba_data < record->start_lba)
+	    record->start_lba = cur_part->lba_data;
+	if (lba_count < record->length)
+	    record->length = lba_count;
+	/* Next comes the GPT partition record length */
+	plen = (uint32_t *) (record + 1);
+	plen[0] = cur_part->private.gpt.size;
+	/* Next comes the GPT partition record copy */
+	memcpy(plen + 1, gp, plen[0]);
+	cur_part->record = record;
+	regs.eax.l = 0x54504721;	/* '!GPT' */
+#if DEBUG
+	mbr_part_dump(record);
+	gpt_part_dump((struct gpt_part *)(plen + 1));
+#endif
+    }
+
     if (cur_part && cur_part->record) {
 	/* 0x7BE is the canonical place for the first partition entry. */
 	data[ndata].data = (void *)cur_part->record;
@@ -1431,8 +1478,10 @@ int main(int argc, char *argv[])
     do_boot(data, ndata, &regs);
 
 bail:
-    if (cur_part)
+    if (cur_part) {
 	free(cur_part->block);
+	free((void *)cur_part->record);
+    }
     free(cur_part);
     free(mbr);
     return 255;