Add a capability query for image number

In addition to the binary capability flags, add a query function that
returns the number of images MCUboot has been configured to support.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

boot/bootutil/include/bootutil/caps.h

@@ -41,6 +41,12 @@ uint32_t bootutil_get_caps(void);
 #define BOOTUTIL_CAP_ENC_KW                 (1<<6)
 #define BOOTUTIL_CAP_VALIDATE_PRIMARY_SLOT  (1<<7)
 
+/*
+ * Query the number of images this bootloader is configured for.  This
+ * is also primarily used for testing.
+ */
+uint32_t bootutil_get_num_images(void);
+
 #ifdef __cplusplus
 }
 #endif

boot/bootutil/src/caps.c

@@ -47,3 +47,12 @@ uint32_t bootutil_get_caps(void)
 
     return res;
 }
+
+uint32_t bootutil_get_num_images(void)
+{
+#if defined(MCUBOOT_IMAGE_NUMBER)
+    return MCUBOOT_IMAGE_NUMBER;
+#else
+    return 1;
+#endif
+}

sim/src/caps.rs

@@ -19,8 +19,15 @@ impl Caps {
         let caps = unsafe { bootutil_get_caps() };
         (caps as u32) & (self as u32) != 0
     }
+
+    /// Query for the number of images that have been configured into this
+    /// MCUboot build.
+    pub fn get_num_images() -> usize {
+        (unsafe { bootutil_get_num_images() }) as usize
+    }
 }
 
 extern "C" {
     fn bootutil_get_caps() -> Caps;
+    fn bootutil_get_num_images() -> u32;
 }