diff --color '--color=auto' --unified --unified --recursive --text ucspi-tcp-0.88/Makefile patch/Makefile
--- ucspi-tcp-0.88/Makefile	2000-03-18 16:18:42.000000000 +0100
+++ patch/Makefile	2023-09-10 13:51:54.334623523 +0200
@@ -159,7 +159,7 @@
 compile: \
 warn-auto.sh conf-cc
 	( cat warn-auto.sh; \
-	echo exec "`head -1 conf-cc`" '-c $${1+"$$@"}' \
+	echo exec "`head -1 conf-cc`" '-include errno.h' '-include unistd.h' '-c $${1+"$$@"}' \
 	) > compile
 	chmod 755 compile
 
diff --color '--color=auto' --unified --unified --recursive --text ucspi-tcp-0.88/readwrite.h patch/readwrite.h
--- ucspi-tcp-0.88/readwrite.h	2000-03-18 16:18:42.000000000 +0100
+++ patch/readwrite.h	2023-09-10 13:53:10.657846842 +0200
@@ -1,7 +1,7 @@
 #ifndef READWRITE_H
 #define READWRITE_H
 
-extern int read();
-extern int write();
+extern ssize_t read();
+extern ssize_t write();
 
 #endif