semaphores: use Mach semaphores functions on MacOS

As macOS doesn't support unnamed semaphores via sem_init, work
around those via Mach semaphores using wrapper functions.
As semaphore_wait() doesn't imply pthread_cancel(), imply that.

src/base/misc/utilities.c

@@ -1024,8 +1024,6 @@ static int pts_open(int pty_fd)
     return pts_fd;
 }
 
-typedef sem_t *pshared_sem_t;
-
 static int pshared_sem_init(pshared_sem_t *sem, unsigned int value)
 {
     char sem_name[] = "/dosemu2_psem_%PXXXXXX";
@@ -1086,7 +1084,7 @@ pid_t run_external_command(const char *path, int argc, const char **argv,
 	pts_fd = pts_open(pty_fd);
 	/* Reading master side before slave opened, results in EOF.
 	 * Notify user that reads are now safe. */
-	sem_post(pty_sem);
+	pshared_sem_post(pty_sem);
 	pshared_sem_destroy(&pty_sem);
 	if (pts_fd == -1) {
 	    error("run_unix_command(): open pts failed %s\n", strerror(errno));
@@ -1140,7 +1138,7 @@ pid_t run_external_command(const char *path, int argc, const char **argv,
     }
     sigprocmask(SIG_SETMASK, &oset, NULL);
     /* wait until its safe to read from pty_fd */
-    sem_wait(pty_sem);
+    pshared_sem_wait(pty_sem);
     pshared_sem_destroy(&pty_sem);
     return pid;
 }

src/include/utilities.h

@@ -106,6 +106,30 @@ FILE *fstream_tee(FILE *orig, FILE *copy);
     pthread_cleanup_pop(0); \
 }
 
+typedef sem_t *pshared_sem_t;
+static inline int pshared_sem_post(sem_t *sem)
+{
+    return sem_post(sem);
+}
+static inline int pshared_sem_wait(sem_t *sem)
+{
+    return sem_wait(sem);
+}
+
+/* macOS doesn't support sem_init(), so use Mach semaphores instead */
+#ifdef __APPLE__
+#include <mach/mach_init.h>
+#include <mach/task.h>
+#include <mach/semaphore.h>
+#undef PAGE_SIZE
+#define PAGE_SIZE 4096
+#define sem_t semaphore_t
+#define sem_init(x,y,z) semaphore_create(mach_task_self(), x, SYNC_POLICY_FIFO, z)
+#define sem_post(x) semaphore_signal(*(x))
+#define sem_wait(x) do {semaphore_wait(*(x)); pthread_testcancel();} while(0)
+#define sem_destroy(x) semaphore_destroy(mach_task_self(), *(x))
+#endif
+
 pid_t run_external_command(const char *path, int argc,
         const char **argv,
         int use_stdin, int close_from, int pty_fd);

src/plugin/fluidsynth/mid_o_flus.c

@@ -37,6 +37,7 @@
 #include "emu.h"
 #include "init.h"
 #include "timers.h"
+#include "utilities.h"
 #include "sound/midi.h"
 #include "sound/sound.h"
 

src/plugin/libao/snd_o_ao.c

@@ -33,6 +33,7 @@
 
 #include "emu.h"
 #include "init.h"
+#include "utilities.h"
 #include "sound/sound.h"
 #include "ao_init.h"
 #include <stdio.h>

src/plugin/munt/munt.c

@@ -29,6 +29,7 @@
 #include "emu.h"
 #include "init.h"
 #include "timers.h"
+#include "utilities.h"
 #include "sound/midi.h"
 #include "sound/sound.h"