coverage: add a wrapper for execveat()

gcov provides wrappers for the exec*() calls but there's none for execveat(),
which means we lose all coverage prior to the call. To mitigate this, let's
add a simple execveat() wrapper in gcov's style[0], which dumps and resets
the coverage data when needed.

This applies only when we're built with -Dfexecve=true.

[0] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/libgcov-interface.c;h=b2ee930864183b78c8826255183ca86e15e21ded;hb=HEAD

1 files changed, 30 insertions, 2 deletions

diff --git a/src/basic/coverage.h b/src/basic/coverage.h
index 640bddc485..3e674a8dba 100644
--- a/src/basic/coverage.h
+++ b/src/basic/coverage.h
@@ -1,6 +1,9 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
+extern void __gcov_dump(void);
+extern void __gcov_reset(void);
+
 /* When built with --coverage (gcov) we need to explicitly call __gcov_dump()
  * in places where we use _exit(), since _exit() skips at-exit hooks resulting
  * in lost coverage.
@@ -8,12 +11,37 @@
  * To make sure we don't miss any _exit() calls, this header file is included
  * explicitly on the compiler command line via the -include directive (only
  * when built with -Db_coverage=true)
- * */
+ */
 extern void _exit(int);
-extern void __gcov_dump(void);
 
 static inline _Noreturn void _coverage__exit(int status) {
         __gcov_dump();
         _exit(status);
 }
 #define _exit(x) _coverage__exit(x)
+
+/* gcov provides wrappers for the exec*() calls but there's none for execveat(),
+ * which means we lose all coverage prior to the call. To mitigate this, let's
+ * add a simple execveat() wrapper in gcov's style[0], which dumps and resets
+ * the coverage data when needed.
+ *
+ * This applies only when we're built with -Dfexecve=true.
+ *
+ * [0] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/libgcov-interface.c;h=b2ee930864183b78c8826255183ca86e15e21ded;hb=HEAD
+ */
+
+extern int execveat(int, const char *, char * const [], char * const [], int);
+
+static inline int _coverage_execveat(
+                        int dirfd,
+                        const char *pathname,
+                        char * const argv[],
+                        char * const envp[],
+                        int flags) {
+        __gcov_dump();
+        int r = execveat(dirfd, pathname, argv, envp, flags);
+        __gcov_reset();
+
+        return r;
+}
+#define execveat(d,p,a,e,f) _coverage_execveat(d, p, a, e, f)