Support booting from compressed kernel images.

The bsd.rd ramdisk now ships gzip'd on amd64. Use libz in base to
transparently handle decompression of any compressed kernel images.

Patch from Josh Rickmar.

ok kn@

1 files changed, 16 insertions, 14 deletions

diff --git a/usr.sbin/vmd/vm.c b/usr.sbin/vmd/vm.c
index 9ffd1598b21..58f441172a0 100644
--- a/usr.sbin/vmd/vm.c
+++ b/usr.sbin/vmd/vm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm.c,v 1.61 2021/03/29 23:37:01 dv Exp $	*/
+/*	$OpenBSD: vm.c,v 1.62 2021/04/05 18:09:48 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -21,6 +21,7 @@
 #include <sys/queue.h>
 #include <sys/wait.h>
 #include <sys/uio.h>
+#include <sys/stat.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/mman.h>
@@ -84,7 +85,7 @@ void vcpu_exit_inout(struct vm_run_params *);
 int vcpu_exit_eptviolation(struct vm_run_params *);
 uint8_t vcpu_exit_pci(struct vm_run_params *);
 int vcpu_pic_intr(uint32_t, uint32_t, uint8_t);
-int loadfile_bios(FILE *, struct vcpu_reg_state *);
+int loadfile_bios(gzFile, off_t, struct vcpu_reg_state *);
 int send_vm(int, struct vm_create_params *);
 int dump_send_header(int);
 int dump_vmr(int , struct vm_mem_range *);
@@ -213,6 +214,7 @@ static const struct vcpu_reg_state vcpu_init_flat16 = {
  *
  * Parameters:
  *  fp: file of a kernel file to load
+ *  size: uncompressed size of the image
  *  (out) vrs: register state to set on init for this kernel
  *
  * Return values:
@@ -220,16 +222,15 @@ static const struct vcpu_reg_state vcpu_init_flat16 = {
  *  various error codes returned from read(2) or loadelf functions
  */
 int
-loadfile_bios(FILE *fp, struct vcpu_reg_state *vrs)
+loadfile_bios(gzFile fp, off_t size, struct vcpu_reg_state *vrs)
 {
-	off_t	 size, off;
+	off_t	 off;
 
 	/* Set up a "flat 16 bit" register state for BIOS */
 	memcpy(vrs, &vcpu_init_flat16, sizeof(*vrs));
 
-	/* Get the size of the BIOS image and seek to the beginning */
-	if (fseeko(fp, 0, SEEK_END) == -1 || (size = ftello(fp)) == -1 ||
-	    fseeko(fp, 0, SEEK_SET) == -1)
+	/* Seek to the beginning of the BIOS image */
+	if (gzseek(fp, 0, SEEK_SET) == -1)
 		return (-1);
 
 	/* The BIOS image must end at 1M */
@@ -277,9 +278,10 @@ start_vm(struct vmd_vm *vm, int fd)
 	struct vcpu_reg_state	 vrs;
 	int			 nicfds[VMM_MAX_NICS_PER_VM];
 	int			 ret;
-	FILE			*fp;
+	gzFile			 fp;
 	size_t			 i;
 	struct vm_rwregs_params  vrp;
+	struct stat		 sb;
 
 	/* Child */
 	setproctitle("%s", vcp->vcp_name);
@@ -331,7 +333,7 @@ start_vm(struct vmd_vm *vm, int fd)
 		memcpy(&vrs, &vcpu_init_flat64, sizeof(vrs));
 
 		/* Find and open kernel image */
-		if ((fp = fdopen(vm->vm_kernel, "r")) == NULL)
+		if ((fp = gzdopen(vm->vm_kernel, "r")) == NULL)
 			fatalx("failed to open kernel - exiting");
 
 		/* Load kernel image */
@@ -339,16 +341,16 @@ start_vm(struct vmd_vm *vm, int fd)
 
 		/*
 		 * Try BIOS as a fallback (only if it was provided as an image
-		 * with vm->vm_kernel and not loaded from the disk)
+		 * with vm->vm_kernel and the file is not compressed)
 		 */
-		if (ret && errno == ENOEXEC && vm->vm_kernel != -1)
-			ret = loadfile_bios(fp, &vrs);
+		if (ret && errno == ENOEXEC && vm->vm_kernel != -1 &&
+		    gzdirect(fp) && (ret = fstat(vm->vm_kernel, &sb)) == 0)
+			ret = loadfile_bios(fp, sb.st_size, &vrs);
 
 		if (ret)
 			fatal("failed to load kernel or BIOS - exiting");
 
-		if (fp)
-			fclose(fp);
+		gzclose(fp);
 	}
 
 	if (vm->vm_kernel != -1)