Fix boot2 to handle boot config files that only contain a custom path to

a loader or kernel.  Specifically, kname cannot be pointed at cmd[] since
it's value is change to be an empty string after the initial call to
parse, and cmd[]'s value can be changed (thus losing a prior setting for
kname) due to user input at the boot prompt.  While here, ensure that that
initial boot config file text is nul-terminated, that ops is initialized
to zero, and that kname is always initialized to a valid string.

Tested by:	Domagoj Smolcic  rank1seeker of gmail
MFC after:	1 week

1 files changed, 15 insertions, 6 deletions

diff --git a/sys/boot/i386/boot2/boot2.c b/sys/boot/i386/boot2/boot2.c
index 3603924..8291249 100644
--- a/sys/boot/i386/boot2/boot2.c
+++ b/sys/boot/i386/boot2/boot2.c
@@ -128,7 +128,7 @@ static struct dsk {
     unsigned start;
     int init;
 } dsk;
-static char cmd[512], cmddup[512];
+static char cmd[512], cmddup[512], knamebuf[1024];
 static const char *kname;
 static uint32_t opts;
 static int comspeed = SIOSPD;
@@ -223,7 +223,9 @@ main(void)
 {
     uint8_t autoboot;
     ino_t ino;
+    size_t nbyte;
 
+    opts = 0;
     kname = NULL;
     dmadat = (void *)(roundup2(__base + (int32_t)&_end, 0x10000) - __base);
     v86.ctl = V86_FLAGS;
@@ -240,8 +242,10 @@ main(void)
     autoboot = 1;
 
     if ((ino = lookup(PATH_CONFIG)) ||
-        (ino = lookup(PATH_DOTCONFIG)))
-	fsread(ino, cmd, sizeof(cmd));
+        (ino = lookup(PATH_DOTCONFIG))) {
+	nbyte = fsread(ino, cmd, sizeof(cmd) - 1);
+	cmd[nbyte] = '\0';
+    }
 
     if (*cmd) {
 	memcpy(cmddup, cmd, sizeof(cmd));
@@ -258,9 +262,9 @@ main(void)
      * or in case of failure, try to load a kernel directly instead.
      */
 
-    if (autoboot && !kname) {
+    if (!kname) {
 	kname = PATH_BOOT3;
-	if (!keyhit(3*SECOND)) {
+	if (autoboot && !keyhit(3*SECOND)) {
 	    load();
 	    kname = PATH_KERNEL;
 	}
@@ -457,7 +461,12 @@ parse()
 			     ? DRV_HARD : 0) + drv;
 		dsk_meta = 0;
 	    }
-            kname = arg;
+	    if ((i = ep - arg)) {
+		if ((size_t)i >= sizeof(knamebuf))
+		    return -1;
+		memcpy(knamebuf, arg, i + 1);
+		kname = knamebuf;
+	    }
 	}
 	arg = p;
     }