[image] Add "--replace" option

Expose image tail-recursion to iPXE scripts via the "--replace"
option.  This functions similarly to exec() under Unix: the
currently-executing script is replaced with the new image (as opposed
to running the new image as a subroutine).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/image.c b/src/core/image.c
index 666ee3de8676323ba319fa0ef942c870eb197ca0..1bf5447f0eee0ecef196e4d6697e8bddee6fd3f0 100644 (file)
--- a/src/core/image.c
+++ b/src/core/image.c
@@ -327,6 +327,14 @@ int image_exec ( struct image *image ) {
        if ( image->flags & IMAGE_AUTO_UNREGISTER )
                unregister_image ( image );
 
+       /* Debug message for tail-recursion.  Placed here because the
+        * image_put() may end up freeing the image.
+        */
+       if ( replacement ) {
+               DBGC ( image, "IMAGE %s replacing self with IMAGE %s\n",
+                      image->name, replacement->name );
+       }
+
        /* Drop temporary reference to the original image */
        image_put ( image );
 
@@ -338,12 +346,8 @@ int image_exec ( struct image *image ) {
        uri_put ( old_cwuri );
 
        /* Tail-recurse into replacement image, if one exists */
-       if ( replacement ) {
-               DBGC ( image, "IMAGE <freed> replacing self with IMAGE %s\n",
-                      replacement->name );
-               if ( ( rc = image_exec ( replacement ) ) != 0 )
-                       return rc;
-       }
+       if ( replacement )
+               return image_exec ( replacement );
 
        return rc;
 }

diff --git a/src/hci/commands/image_cmd.c b/src/hci/commands/image_cmd.c
index 38d814cde1f58f5a738adac8ce062ded864fc379..0a4232f27a54fbab08ac04fe73dae8fbfd29f0d7 100644 (file)
--- a/src/hci/commands/image_cmd.c
+++ b/src/hci/commands/image_cmd.c
@@ -26,6 +26,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/image.h>
 #include <ipxe/command.h>
 #include <ipxe/parseopt.h>
+#include <ipxe/shell.h>
 #include <usr/imgmgmt.h>
 
 /** @file
@@ -38,6 +39,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 struct imgsingle_options {
        /** Image name */
        const char *name;
+       /** Replace image */
+       int replace;
        /** Free image after execution */
        int autofree;
 };
@@ -46,6 +49,8 @@ struct imgsingle_options {
 static struct option_descriptor imgsingle_opts[] = {
        OPTION_DESC ( "name", 'n', required_argument,
                      struct imgsingle_options, name, parse_string ),
+       OPTION_DESC ( "replace", 'r', no_argument,
+                     struct imgsingle_options, replace, parse_flag ),
        OPTION_DESC ( "autofree", 'a', no_argument,
                      struct imgsingle_options, autofree, parse_flag ),
 };
@@ -66,7 +71,8 @@ struct imgsingle_descriptor {
        /** Pre-action to take upon image, or NULL */
        void ( * preaction ) ( struct image *image );
        /** Action to take upon image, or NULL */
-       int ( * action ) ( struct image *image );
+       int ( * action ) ( struct image *image,
+                          struct imgsingle_options *opts );
        /** Verb to describe action */
        const char *verb;
 };
@@ -145,7 +151,7 @@ static int imgsingle_exec ( int argc, char **argv,
 
        /* Carry out command action, if applicable */
        if ( desc->action ) {
-               if ( ( rc = desc->action ( image ) ) != 0 ) {
+               if ( ( rc = desc->action ( image, &opts ) ) != 0 ) {
                        printf ( "Could not %s: %s\n",
                                 desc->verb, strerror ( rc ) );
                        goto err_action;
@@ -188,11 +194,23 @@ static int imgfetch_exec ( int argc, char **argv ) {
        return imgsingle_exec ( argc, argv, &imgfetch_desc );
 }
 
+/**
+ * "imgselect" command action
+ *
+ * @v image            Image
+ * @v opts             Options
+ * @ret rc             Return status code
+ */
+static int imgselect ( struct image *image,
+                      struct imgsingle_options *opts __unused ) {
+       return image_select ( image );
+}
+
 /** "imgselect" family command descriptor */
 struct imgsingle_descriptor imgselect_desc = {
        .cmd = &imgsingle_cmd,
        .acquire = imgacquire,
-       .action = image_select,
+       .action = imgselect,
        .verb = "select",
 };
 
@@ -211,13 +229,44 @@ static int imgselect_exec ( int argc, char **argv ) {
 static struct command_descriptor imgexec_cmd =
        COMMAND_DESC ( struct imgsingle_options, imgsingle_opts,
                       0, MAX_ARGUMENTS,
-                      "[--autofree] [<uri|image> [<arguments>...]]" );
+                      "[--autofree] [--replace] "
+                      "[<uri|image> [<arguments>...]]" );
+
+/**
+ * "imgexec" command action
+ *
+ * @v image            Image
+ * @v opts             Options
+ * @ret rc             Return status code
+ */
+static int imgexec ( struct image *image, struct imgsingle_options *opts ) {
+       int rc;
+
+       /* Perform replacement or execution as applicable */
+       if ( opts->replace ) {
+
+               /* Try to replace image */
+               if ( ( rc = image_replace ( image ) ) != 0 )
+                       return rc;
+
+               /* Stop script and tail-recurse into replacement image */
+               shell_stop ( SHELL_STOP_COMMAND_SEQUENCE );
+
+       } else {
+
+               /* Try to execute image */
+               if ( ( rc = image_exec ( image ) ) != 0 )
+                       return rc;
+       }
+
+       return 0;
+}
 
 /** "imgexec" family command descriptor */
 struct imgsingle_descriptor imgexec_desc = {
        .cmd = &imgexec_cmd,
        .acquire = imgacquire,
-       .action = image_exec,
+       .action = imgexec,
        .verb = "boot",
 };