error: unknown type name 'u_char'; did you mean 'char'?

[fbion]

CC src/signal.o

src/signal.c:18:19: error: unknown type name 'u_char'; did you mean 'char'?
read_file(int fd, u_char buf, size_t size, off_t offset) {
^~~~~~
char
src/signal.c:31:5: error: use of undeclared identifier 'u_char'
u_char buf[10];
^
src/signal.c:40:23: error: use of undeclared identifier 'buf'
n = read_file(fd, buf, 10, 0);
^
src/signal.c:48:20: error: use of undeclared identifier 'buf'
while (n-- && (buf[n] == CR || buf[n] == LF)) { / void / }
^
src/signal.c:48:36: error: use of undeclared identifier 'buf'
while (n-- && (buf[n] == CR || buf[n] == LF)) { / void / }
^
src/signal.c:50:30: error: use of undeclared identifier 'buf'
return atoi((const char)buf);
^
6 errors generated.
make: *** [src/signal.o] Error 1

cc -v
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix

[lparam]

you can try modify u_char to uint8_t.
i have not tested on ios.
just linux and openwrt trunk.
pull request welcome:)