Check for a terminating LAR member which tells us that no further LAR
member except the bootblock will be found after this member.
The LAR member has a normal MAGIC, but all other parts of struct
lar_header are 0xff. That way, adding a new member in place of the
terminating member will not need an erase cycle.
Signed-off-by: Carl-Daniel Hailfinger <[EMAIL PROTECTED]>
Index: LinuxBIOSv3-larplaceholder/lib/lar.c
===================================================================
--- LinuxBIOSv3-larplaceholder/lib/lar.c (Revision 546)
+++ LinuxBIOSv3-larplaceholder/lib/lar.c (Arbeitskopie)
@@ -58,7 +58,7 @@
int find_file(const struct mem_file *archive, const char *filename, struct
mem_file *result)
{
- char *walk, *fullname;
+ char *walk, *fullname, *tmp;
struct lar_header *header;
printk(BIOS_INFO, "LAR: Attempting to open '%s'.\n", filename);
@@ -105,10 +105,24 @@
for (walk = archive->start;
(walk < (char *)(archive->start + archive->len - sizeof(struct
lar_header))) &&
(walk >= (char *)archive->start); walk += 16) {
- if (strncmp(walk, MAGIC, 8) != 0)
+ if (strncmp(walk, MAGIC, sizeof(header->magic)) != 0)
continue;
header = (struct lar_header *)walk;
+ /* The loop below deserves an explanation: The final iteration
+ * of the loop will access the byte after the header. If that
+ * iteration has been reached, all checked bytes in the header
+ * were 0xff. This saves one state variable.
+ */
+ for (tmp = walk + sizeof(header->magic);
+ tmp <= walk + sizeof(*header); tmp++) {
+ if (*tmp != (char)0xff)
+ break;
+ }
+ if (tmp == walk + sizeof(*header)) {
+ printk(BIOS_SPEW, "LAR: termination pseudomember
reached.\n");
+ break;
+ }
fullname = walk + sizeof(struct lar_header);
printk(BIOS_SPEW, "LAR: seen member %s\n", fullname);
--
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