testsuite: optional limiting of coverage dumps

Add an option that excludes generation of a given path of `.gcda` files
when running coverage testing. This can be useful when running testing
coverage on downstream repos, which would otherwise result in large
`.gcda` files for paths we don't care about filling up the disk.

One example of using this is to exclude coverage outputs from
mbedtls files with the following:
`CONFIG_COVERAGE_DUMP_PATH_EXCLUDE="*modules/crypto/mbedtls*"`

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

subsys/testsuite/Kconfig

@@ -95,6 +95,15 @@ config COVERAGE_DUMP
 
 endchoice
 
+config COVERAGE_DUMP_PATH_EXCLUDE
+	string "Exclude files matching this pattern from the coverage data"
+	default ""
+	help
+	  Filenames are matched against the pattern using the POSIX fnmatch
+	  function. Filenames are based on their path in the build folder, not the
+	  original source tree. The empty string "" disables the pattern
+	  matching.
+
 endif # COVERAGE_GCOV
 
 config FORCE_COVERAGE

subsys/testsuite/coverage/coverage.c

@@ -9,6 +9,7 @@
 #include <stdint.h>
 #include <errno.h>
 #include <string.h>
+#include <fnmatch.h>
 #include "coverage.h"
 
 K_HEAP_DEFINE(gcov_heap, CONFIG_COVERAGE_GCOV_HEAP_SIZE);
@@ -315,6 +316,11 @@ void gcov_coverage_dump(void)
 	}
 	printk("\nGCOV_COVERAGE_DUMP_START");
 	while (gcov_list) {
+		if ((strlen(CONFIG_COVERAGE_DUMP_PATH_EXCLUDE) > 0) &&
+		    (fnmatch(CONFIG_COVERAGE_DUMP_PATH_EXCLUDE, gcov_list->filename, 0) == 0)) {
+			/* Don't print a note here, it would be interpreted as dump data */
+			goto file_dump_end;
+		}
 
 		dump_on_console_start(gcov_list->filename);
 		size = gcov_calculate_buff_size(gcov_list);
@@ -334,6 +340,7 @@ void gcov_coverage_dump(void)
 		dump_on_console_data(buffer, size);
 
 		k_heap_free(&gcov_heap, buffer);
+file_dump_end:
 		gcov_list = gcov_list->next;
 		if (gcov_list_first == gcov_list) {
 			goto coverage_dump_end;