implement fexecve

src/process/fexecve.c

@@ -0,0 +1,10 @@
+#include <unistd.h>
+#include <stdio.h>
+
+int fexecve(int fd, char *const argv[], char *const envp[])
+{
+	static const char proc[] = "/proc/self/fd/%d";
+	char buf[sizeof proc + 3*sizeof(int)];
+	snprintf(buf, sizeof buf, proc, fd);
+	return execve(buf, argv, envp);
+}