libflashrom: Add layout "exclude" API

Layouts can be expensive to derive (reading from flash), so we might
want to reuse a layout for different purposes. Today, it's not possible
to undo a flashrom_layout_include_region() operation (to, say, operate
on a different region). Add such an API.

Change-Id: I7ea3e0674f25e34bf2cfc8f464ae7ca1c1a3fbfd
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/76005
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Nikolai Artemiev <nartemiev@google.com>

bindings/rust/libflashrom/src/lib.rs

@@ -879,6 +879,32 @@ impl Layout {
         }
     }
 
+    /// Exclude a region
+    ///
+    /// # Errors
+    ///
+    /// This function will return an error if the region is not a valid CString,
+    /// or if libflashrom returns an error.
+    pub fn exclude_region(&mut self, region: &str) -> std::result::Result<(), RegionError> {
+        let err = {
+            let region = CString::new(region)?;
+            unsafe {
+                libflashrom_sys::flashrom_layout_exclude_region(
+                    self.layout.as_mut(),
+                    region.as_ptr(),
+                )
+            }
+        };
+        if err != 0 {
+            Err(RegionError::ErrorCode(ErrorCode {
+                function: "flashrom_layout_exclude_region",
+                code: err,
+            }))
+        } else {
+            Ok(())
+        }
+    }
+
     /// Get the [`Range`] for the given region
     ///
     /// # Errors

include/libflashrom.h

@@ -420,6 +420,16 @@ int flashrom_layout_add_region(struct flashrom_layout *layout, size_t start, siz
  *         1 if the given name can't be found.
  */
 int flashrom_layout_include_region(struct flashrom_layout *layout, const char *name);
+/**
+ * @brief Mark given region as not included.
+ *
+ * @param layout The layout to alter.
+ * @param name   The name of the region to exclude.
+ *
+ * @return 0 on success,
+ *         1 if the given name can't be found.
+ */
+int flashrom_layout_exclude_region(struct flashrom_layout *layout, const char *name);
 /**
  * @brief Get given region's offset and length.
  *

layout.c

@@ -217,6 +217,17 @@ static int include_region(struct flashrom_layout *const l, const char *name,
 	return 1;
 }
 
+/* returns 0 to indicate success, 1 to indicate failure */
+static int exclude_region(struct flashrom_layout *const l, const char *name)
+{
+	struct romentry *const entry = _layout_entry_by_name(l, name);
+	if (entry) {
+		entry->included = false;
+		return 0;
+	}
+	return 1;
+}
+
 /* returns -1 if an entry is not found, 0 if found. */
 static int romentry_exists(struct flashrom_layout *const l, char *name, char *file)
 {
@@ -441,6 +452,11 @@ int flashrom_layout_include_region(struct flashrom_layout *const layout, const c
 	return include_region(layout, name, NULL);
 }
 
+int flashrom_layout_exclude_region(struct flashrom_layout *const layout, const char *name)
+{
+	return exclude_region(layout, name);
+}
+
 int flashrom_layout_get_region_range(struct flashrom_layout *const l, const char *name,
 			      unsigned int *start, unsigned int *len)
 {

libflashrom.map

@@ -15,6 +15,7 @@ LIBFLASHROM_1.0 {
     flashrom_image_write;
     flashrom_init;
     flashrom_layout_add_region;
+    flashrom_layout_exclude_region;
     flashrom_layout_get_region_range;
     flashrom_layout_include_region;
     flashrom_layout_new;

tests/layout.c

@@ -110,6 +110,8 @@ void layout_pass_sanity_checks_test_success(void **state)
 
 	unsigned int region_start = 0x00021000;
 	unsigned int region_end = 0x00031000;
+	unsigned int region2_start = 0x00041000;
+	unsigned int region2_end = 0x00051000;
 	unsigned int start = 0;
 	unsigned int len = 0;
 
@@ -119,6 +121,9 @@ void layout_pass_sanity_checks_test_success(void **state)
 	assert_int_equal(0, flashrom_layout_new(&layout));
 	assert_int_equal(0, flashrom_layout_add_region(layout, region_start, region_end, "region"));
 	assert_int_equal(0, flashrom_layout_include_region(layout, "region"));
+	assert_int_equal(0, flashrom_layout_add_region(layout, region2_start, region2_end, "region2"));
+	assert_int_equal(0, flashrom_layout_include_region(layout, "region2"));
+	assert_int_equal(0, flashrom_layout_exclude_region(layout, "region2"));
 	printf("done\n");
 
 	printf("Asserting region range... ");