implement fexecve

include/unistd.h

@@ -86,6 +86,7 @@ int execle(const char *, ...);
 int execl(const char *, ...);
 int execvp(const char *, char *const []);
 int execlp(const char *, ...);
+int fexecve(int, char *const [], char *const []);
 void _exit(int);
 
 pid_t getpid(void);

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);
+}