I put a more more effort into trying to build it...

Installed a whole bunch of libraries with MacPorts, tweaked some include/lib paths, added the odd extra include (sys/dir.h), created byteswap.h etc etc

But I still can't get it to build. I am stuck at:

cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o mp3tofid.o mp3tofid.c
mp3tofid.c: In function ‘sourcefiletofidnumber’:
mp3tofid.c:464: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 5 has type ‘ino_t’
mp3tofid.c:466: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 7 has type ‘ino_t’
mp3tofid.c: In function ‘dirscan’:
mp3tofid.c:939: warning: passing argument 4 of ‘scandir’ from incompatible pointer type
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o scanmp3.o scanmp3.c
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o scanwave.o scanwave.c
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o scanwma.o scanwma.c
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o scanvorbis.o scanvorbis.c
/opt/local/include/vorbis/vorbisfile.h:75: warning: ‘OV_CALLBACKS_DEFAULT’ defined but not used
/opt/local/include/vorbis/vorbisfile.h:82: warning: ‘OV_CALLBACKS_NOCLOSE’ defined but not used
/opt/local/include/vorbis/vorbisfile.h:89: warning: ‘OV_CALLBACKS_STREAMONLY’ defined but not used
/opt/local/include/vorbis/vorbisfile.h:96: warning: ‘OV_CALLBACKS_STREAMONLY_NOCLOSE’ defined but not used
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o scanflac.o scanflac.c
cc -O2 -g -I/opt/local/include -L/opt/local/lib -Wall -Wpointer-arith -Wbad-function-cast -Wcast-align -Wnested-externs -c -o iconv.o iconv.c
cc -g -L/opt/local/lib -o mp3tofid mp3tofid.o scanmp3.o scanwave.o scanwma.o scanvorbis.o scanflac.o iconv.o -lpopt -lgdbm -lcrypto -lmad -lid3tag -lvorbisfile -lvorbis -logg -lsndfile -lFLAC -lz -lm
Undefined symbols:
"_libiconv", referenced from:
_codesetconv in iconv.o
_codesetconv in iconv.o
"_libiconv_open", referenced from:
_eiconv_open in iconv.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
make: *** [mp3tofid] Error 1

Any clues anyone ? It is a long time since I was messing about getting random Unix code to build...