fix: getprogname() is not implemented

Signed-off-by: sisungo <[email protected]>

compat.h

@@ -1,13 +1,30 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
+#include <libgen.h>
 
 #ifndef __DECONST
 #define __DECONST(type, var)    ((type)(uintptr_t)(const void *)(var))
 #endif
 
+#ifdef MAINFILE
+const char *PROGNAME = NULL;
+
+static inline void initprogname(const char *argv0) {
+    PROGNAME = "grep";
+    if (argv0 && argv0[0]) {
+        char *copied_argv0 = strdup(argv0);
+	if (!copied_argv0) return;
+	PROGNAME = basename(copied_argv0);
+    }
+}
+#else
+extern const char *PROGNAME;
+#endif
+
 static inline const char *getprogname() {
-    return "grep";
+    if (!PROGNAME) abort();
+    return PROGNAME;
 }
 
 static inline void warnc(int code, const char *fmt, ...) {

grep.c

@@ -47,6 +47,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#define MAINFILE
 #include "compat.h"
 #include "grep.h"
 
@@ -319,6 +320,7 @@ main(int argc, char *argv[])
 	int c, lastc, needpattern, newarg, prevoptind;
 	bool matched;
 
+	initprogname(argv[0]);
 	setlocale(LC_ALL, "");
 
 	/*