Make it build on MacOS X.

I only compile-tested it, I didn't run it.
The main effect is to make hardware tape support ~optional, since OSX
has no <sys/mtio.h>.

src/cenv.h

@@ -172,22 +172,25 @@
 #  define CENV_SYS_DECOSF 1
 # elif defined(__FreeBSD__)
 #  undef  CENV_SYS_FREEBSD
-#  define CENV_SYS_FREEBSD 1 
+#  define CENV_SYS_FREEBSD 1
 # elif defined(__linux__)
 #  undef  CENV_SYS_LINUX
 #  define CENV_SYS_LINUX 1
-# elif defined(__APPLE__)
+# elif defined(__APPLE__) && !defined(__MACH__)
 #  undef  CENV_SYS_MAC
-#  define CENV_SYS_MAC 1 
+#  define CENV_SYS_MAC 1
+# elif defined(__APPLE__) && defined(__MACH__)
+#  define CENV_SYS_BSD 1
+#  define CENV_SYS_XBSD 1
 # elif defined(__NetBSD__)
 #  undef  CENV_SYS_NETBSD
-#  define CENV_SYS_NETBSD 1 
+#  define CENV_SYS_NETBSD 1
 # elif defined(__OpenBSD__)
 #  undef  CENV_SYS_OPENBSD
-#  define CENV_SYS_OPENBSD 1 
+#  define CENV_SYS_OPENBSD 1
 # elif defined(__sun) && defined(__SVR4)
 #  undef  CENV_SYS_SOLARIS
-#  define CENV_SYS_SOLARIS 1 
+#  define CENV_SYS_SOLARIS 1
 # elif defined(__COMPILER_KCC__)
 #  undef  CENV_SYS_T20		/* Not quite right, but close enough */
 #  define CENV_SYS_T20 1

src/dpsup.c

@@ -53,11 +53,11 @@ static int decosfcclossage;
 # include <sys/mman.h>
 # include <unistd.h>
 # include <signal.h>
-# if CENV_SYS_SUN || CENV_SYS_SOLARIS
+# if defined(MAXSIG)
 #  define SIGMAX MAXSIG		/* Different wording on Sun */
-# elif CENV_SYS_FREEBSD
+# elif defined(NSIG)
 #  define SIGMAX NSIG
-# elif CENV_SYS_NETBSD || CENV_SYS_LINUX
+# elif defined(_NSIG)
 #  define SIGMAX _NSIG
 # endif
 #endif /* CENV_SYS_DECOSF || CENV_SYS_SUN || CENV_SYS_SOLARIS || CENV_SYS_XBSD || CENV_SYS_LINUX */

src/dptm03.c

@@ -222,7 +222,9 @@ So, algorithm (on DECOSF anyway) should be:
 # include <sys/file.h>
 # include <sys/ioctl.h>
 # include <sys/time.h>
-# include <sys/mtio.h>
+# if HAVE_SYS_MTIO_H
+#  include <sys/mtio.h>
+# endif
 # include <sys/types.h>
 # include <sys/ioctl.h>
 #endif
@@ -1337,7 +1339,7 @@ os_mtmoveinit(register struct devmt *d)
     d->mta_frms = 0;
 }
 
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
 /* General-purpose ioctl operation invocation
 */
 int
@@ -1358,6 +1360,7 @@ osux_mtop(register struct devmt *d, int op, int cnt, char *name)
     }
     return TRUE;
 }
+#endif /* CENV_SYS_UNIX && HAVE_SYS_MTIO_H */
 
 /* Get physical magtape state.
  * Unfortunately there is no general way to do this.
@@ -1529,7 +1532,6 @@ os_mtstate(register struct devmt *d,
     }
     return res;
 }
-#endif /* CENV_SYS_UNIX */
 
 /* Called when an unexpected error is hit -- attempts to determine
  * whether the tape is still there or if it's a real data error.
@@ -1610,7 +1612,7 @@ os_mterrchk(register struct devmt *d,
 	}
 	/* OK, should have good state bits now */
     }
-#else
+#elif HAVE_SYS_MTIO_H
     /* Error may indicate tape is no longer present or drive is gone.
        Try to distinguish this error from a real data I/O error
        by performing a NOP.
@@ -1637,7 +1639,7 @@ os_mtopen(struct devmt *d, char *path, int mtof)
 
     os_mtflaginit(d);	/* Clear all state flags */
 
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
   {
     int fd;
     int mode = ((mtof & OS_MTOF_READONLY) ? O_RDONLY   : O_RDWR)
@@ -1822,7 +1824,7 @@ os_mtweof(struct devmt *d)		/* Write a tapemark */
 {
     os_mtmoveinit(d);	/* Clear movement flags */
 
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     if (!osux_mtop(d, MTWEOF, 1, "MTWEOF")) {
 	syserr(-1, "Tapemark write error");
 	os_mterrchk(d, -DPTM_WTM);	 /* Try to recover state from OS */
@@ -1847,7 +1849,7 @@ os_mtunload(struct devmt *d)		/* Try to unload tape */
 {
     d->mta_mol = FALSE;		/* Say no longer online */
     os_mtmoveinit(d);		/* Clear movement flags */
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     lseek(d->d_fd, (long)0, 0);		/* Barf - See DECOSF "man mtio" */
 
     /* Do MTUNLOAD.  Known to be defined by DECOSF and LINUX; other
@@ -1873,7 +1875,7 @@ os_mtrewind(struct devmt *d)		/* Rewind tape */
     os_mtmoveinit(d);		/* Clear movement flags */
     d->mta_rew = TRUE;		/* Now rewinding */
 
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     lseek(d->d_fd, (long)0, 0);		/* Barf - See DECOSF "man mtio" */
     if (!osux_mtop(d, MTREW, 1, "MTREW")) {
 	syserr(-1, "Tape rewind error");
@@ -1919,7 +1921,7 @@ os_mtrewind(struct devmt *d)		/* Rewind tape */
 int
 os_mtspace(struct devmt *d, long unsigned int cnt, int revf)
 {
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     int op = (revf ? MTBSR : MTFSR);
     int dir = (revf ? -1 : 1);
     int prevfileno;
@@ -2022,7 +2024,7 @@ os_mtspace(struct devmt *d, long unsigned int cnt, int revf)
 int
 os_mtfspace(struct devmt *d, long unsigned int cnt, int revf)
 {
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     int op = (revf ? MTBSF : MTFSF);
     int dir = (revf ? -1 : 1);
     int prevfileno;
@@ -2094,7 +2096,7 @@ int
 os_mtclrerr(struct devmt *d)
 {
     /* Do MTCSE.  Known to be defined only by DECOSF? */
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
 # if CENV_SYS_SUN || CENV_SYS_SOLARIS || CENV_SYS_BSD || CENV_SYS_LINUX
 #  ifndef MTCSE			/* No equiv, try NOP instead */
 #   define MTCSE MTNOP
@@ -2106,7 +2108,7 @@ os_mtclrerr(struct devmt *d)
     d->mta_err = 0;
     return TRUE;
 #else
-    return FALSE
+    return FALSE;
 #endif
 }
 
@@ -2139,7 +2141,7 @@ struct mtget {
 void
 os_mtshow(struct devmt *d, FILE *f)
 {
-#if CENV_SYS_UNIX
+#if CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     struct mtget mt;
 
     if (ioctl(d->d_fd, MTIOCGET, (char *)&mt) < 0) {

src/osdnet.c

@@ -502,6 +502,7 @@ osn_ifnmlookup(char *ifnam,		/* Interface name */
 }
 
 #if CENV_SYS_LINUX
+
 int
 set_proc_variable(char *template, char *ifname, char *value)
 {
@@ -522,9 +523,9 @@ set_proc_variable(char *template, char *ifname, char *value)
 }
 
 #endif /* CENV_SYS_LINUX */
+
 /* OSN_ARP_STUFF - stuff emulated-host ARP entry into kernel.
-**	Note it isn't necessary to specify an interface!
-**	Also, the code assumes that if an ARP entry already exists in the
+**	The code assumes that if an ARP entry already exists in the
 **	kernel for the given IP address, it will be reset to this new
 **	setting rather than (eg) failing.
 */
@@ -590,7 +591,7 @@ osn_arp_stuff(char *ifname, unsigned char *ipa, unsigned char *eap, int pubf)
     if (set_proc_variable("/proc/sys/net/ipv4/ip_forward", "", "1\n")) {
 	dbprintln("Enabled net.ipv4.ip_forward");
     }
-#endif /* OSN_USE_IPONLY */
+# endif /* OSN_USE_IPONLY */
     /*
      * It seems that if arp_accept=0, then ARP packets that are received
      * are not only ignored by the kernel, but also not passed to
@@ -1459,7 +1460,6 @@ error:
  * Receives a single packet and returns its size.
  * Include link-layer headers, but no BPF headers or anything like that.
  */
-inline
 ssize_t
 osn_pfread_pcap(struct pfdata *pfdata, void *buf, size_t nbytes)
 {
@@ -1513,7 +1513,6 @@ tryagain:
  * Expect a full ethernet frame including link-layer header.
  * returns the number of bytes written.
  */
-inline
 int
 osn_pfwrite_pcap(struct pfdata *pfdata, const void *buf, size_t nbytes)
 {

src/tapedd.c

@@ -72,7 +72,9 @@
 # include <unistd.h>		/* Basic Unix syscalls */ 
 # include <sys/types.h>
 # include <sys/ioctl.h>
-# include <sys/mtio.h>
+# if HAVE_SYS_MTIO_H
+#  include <sys/mtio.h>
+# endif /* HAVE_SYS_MTIO_H */
 # define char8 unsigned char
 # define O_BSIZE_8 0
 # define NULLDEV "/dev/null"
@@ -1466,6 +1468,8 @@ int os_mtweof(struct dev *dp)		/* Write a tapemark */
     acs[1] = dp->d_fd;
     acs[2] = monsym(".MOCLE");
     jsys(MTOPR, acs);
+#elif CENV_SYS_UNIX && !HAVE_SYS_MTIO_H
+    return FALSE;
 #else
     struct mtop mtcmd;
     mtcmd.mt_op = MTWEOF;
@@ -1486,6 +1490,8 @@ int os_mtfsr(struct dev *dp)	/* Forward Space Record (to inter-record gap)*/
     acs[2] = monsym(".MOCLE");
     jsys(MTOPR, acs);
 */
+#elif CENV_SYS_UNIX && !HAVE_SYS_MTIO_H
+    return FALSE;
 #else
     struct mtop mtcmd;
     mtcmd.mt_op = MTFSR;
@@ -1537,7 +1543,7 @@ t20status(register struct dev *d, register FILE *f, int swd, int cnt)
 void os_mtstatus(struct dev *dp, FILE *f)
 {
 #if CENV_SYS_T20
-#elif CENV_SYS_UNIX
+#elif CENV_SYS_UNIX && HAVE_SYS_MTIO_H
     struct mtget mtstatb;
 
     if (ioctl(dp->d_fd, MTIOCGET, (char *)&mtstatb) < 0) {

src/vdkfmt.c

@@ -52,7 +52,6 @@
 # include <unistd.h>		/* Basic Unix syscalls */
 # include <sys/types.h>
 # include <sys/ioctl.h>
-# include <sys/mtio.h>
 # define NULLDEV "/dev/null"
 # define FD_STDIN 0
 # define FD_STDOUT 1