Use -fmacro-prefix-map to strip build path

Because meson does not provide a simple way to get the relative build
path, it is computed with a pair of foreach loops. As meson does not
have a simple way to compute string length (except via underscorify
and 63 split operations), the build script uses a shell command
instead.

If the compiler does not suppot -fmacro-prefix-map, then fall back
to passing in the relative path prefix, and use its length to offset
the uses of __FILE__ in log messages so that the build path is at
least still not included in the logs. This is significantly more
efficient than calling _sway_strip_path.

1 files changed, 10 insertions, 6 deletions

diff --git a/include/log.h b/include/log.h
index adf431ab..41399a9f 100644
--- a/include/log.h
+++ b/include/log.h
@@ -33,22 +33,26 @@ void _sway_vlog(sway_log_importance_t verbosity, const char *format, va_list arg
 void _sway_abort(const char *filename, ...) ATTRIB_PRINTF(1, 2);
 bool _sway_assert(bool condition, const char* format, ...) ATTRIB_PRINTF(2, 3);
 
-// TODO: get meson to precompute this, for better reproducibility/less overhead
-const char *_sway_strip_path(const char *filepath);
+#ifdef SWAY_REL_SRC_DIR
+// strip prefix from __FILE__, leaving the path relative to the project root
+#define _SWAY_FILENAME ((const char *)__FILE__ + sizeof(SWAY_REL_SRC_DIR) - 1)
+#else
+#define _SWAY_FILENAME __FILE__
+#endif
 
 #define sway_log(verb, fmt, ...) \
-        _sway_log(verb, "[%s:%d] " fmt, _sway_strip_path(__FILE__), __LINE__, ##__VA_ARGS__)
+        _sway_log(verb, "[%s:%d] " fmt, _SWAY_FILENAME, __LINE__, ##__VA_ARGS__)
 
 #define sway_vlog(verb, fmt, args) \
-        _sway_vlog(verb, "[%s:%d] " fmt, _sway_strip_path(__FILE__), __LINE__, args)
+        _sway_vlog(verb, "[%s:%d] " fmt, _SWAY_FILENAME, __LINE__, args)
 
 #define sway_log_errno(verb, fmt, ...) \
         sway_log(verb, fmt ": %s", ##__VA_ARGS__, strerror(errno))
 
 #define sway_abort(FMT, ...) \
-        _sway_abort("[%s:%d] " FMT, _sway_strip_path(__FILE__), __LINE__, ##__VA_ARGS__)
+        _sway_abort("[%s:%d] " FMT, _SWAY_FILENAME, __LINE__, ##__VA_ARGS__)
 
 #define sway_assert(COND, FMT, ...) \
-        _sway_assert(COND, "[%s:%d] %s:" FMT, _sway_strip_path(__FILE__), __LINE__, __PRETTY_FUNCTION__, ##__VA_ARGS__)
+        _sway_assert(COND, "[%s:%d] %s:" FMT, _SWAY_FILENAME, __LINE__, __PRETTY_FUNCTION__, ##__VA_ARGS__)
 
 #endif