Implement mmap support with STORE and RETRIEVE notifications

This one doesn't use server side mmap of the fuse device to access the
contents of the client side memory maps.  Instead it uses the STORE
and RETRIEVE notifications for this purpose.

Makefile

@@ -22,7 +22,7 @@ OSSP_PADSP_CFLAGS := $(shell pkg-config --cflags libpulse)
 endif
 
 ifeq "$(origin OSSP_PADSP_LDFLAGS)" "undefined"
-OSSP_PADSP_LDFLAGS := $(shell pkg-config --libs libpulse)
+OSSP_PADSP_LDFLAGS := $(shell pkg-config --libs libpulse) -lpthread
 endif
 
 ifeq "$(origin OSSP_ALSAP_CFLAGS)" "undefined"

ossp-padsp.c

@@ -784,6 +784,58 @@ static ssize_t padsp_open(enum ossp_opcode opcode,
 	return 0;
 }
 
+static void notify_mmap_fill_play(size_t mmap_size, size_t pos, size_t bytes)
+{
+	while (bytes) {
+		ssize_t ret;
+		size_t count = min(bytes, mmap_size - pos);
+		struct ossp_notify event = { .magic = OSSP_NOTIFY_MAGIC,
+					     .opcode = OSSP_NOTIFY_FILL };
+
+		ossp_mmap_transfer[PLAY].pos = pos;
+		ossp_mmap_transfer[PLAY].bytes = count;
+
+		ret = write(ossp_notify_fd, &event, sizeof(event));
+		if (ret != sizeof(event)) {
+			if (errno != EPIPE)
+				err_e(-errno, "write to notify_fd failed");
+
+			padsp_done();
+			return;
+		}
+		sem_wait(&ossp_mmap_transfer[PLAY].sem);
+
+		bytes -= count;
+		pos = (pos + count) % mmap_size;
+	}
+}
+
+static void notify_mmap_store_rec(size_t mmap_size, size_t pos, size_t bytes)
+{
+	while (bytes) {
+		ssize_t ret;
+		size_t count = min(bytes, mmap_size - pos);
+		struct ossp_notify event = { .magic = OSSP_NOTIFY_MAGIC,
+					     .opcode = OSSP_NOTIFY_STORE };
+
+		ossp_mmap_transfer[REC].pos = pos;
+		ossp_mmap_transfer[REC].bytes = count;
+
+		ret = write(ossp_notify_fd, &event, sizeof(event));
+		if (ret != sizeof(event)) {
+			if (errno != EPIPE)
+				err_e(-errno, "write to notify_fd failed");
+
+			padsp_done();
+			return;
+		}
+		sem_wait(&ossp_mmap_transfer[REC].sem);
+
+		bytes -= count;
+		pos = (pos + count) % mmap_size;
+	}
+}
+
 static void mmap_fill_pstg(void)
 {
 	struct ring_buf *stg = &mmap_stg[PLAY];
@@ -812,6 +864,8 @@ static void mmap_fill_pstg(void)
 		bytes = space;
 	}
 
+	notify_mmap_fill_play(mmap_size, mmap_idx[PLAY] % mmap_size, bytes);
+
 	ring_manual_init(&mmap, mmap_map[PLAY], mmap_size,
 			 new_idx % mmap_size, bytes);
 
@@ -898,6 +952,8 @@ static void mmap_consume_rstg(void)
 		space -= todo;
 	}
 
+	notify_mmap_store_rec(mmap_size, fill_idx % mmap_size, ring_bytes(&mmap));
+
  skip:
 	mmap_idx[REC] = new_idx;
 }

ossp-slave.c

@@ -32,22 +32,21 @@ static const char *usage =
 "    -c CMD_FD         fd to receive commands from osspd\n"
 "    -n NOTIFY_FD      fd to send async notifications to osspd\n"
 "    -m MMAP_FD        fd to use for mmap\n"
-"    -o MMAP_OFFSET    mmap offset\n"
 "    -s MMAP_SIZE      mmap size\n"
 "    -l LOG_LEVEL      set log level\n"
 "    -t                enable log timestamps\n";
 
 char ossp_user_name[OSSP_USER_NAME_LEN];
 int ossp_cmd_fd = -1, ossp_notify_fd = -1;
 void *ossp_mmap_addr[2];
+struct ossp_transfer *ossp_mmap_transfer;
 
 void ossp_slave_init(int argc, char **argv)
 {
 	int have_uid = 0, have_gid = 0;
 	uid_t uid;
 	gid_t gid;
 	int mmap_fd = -1;
-	off_t mmap_off = 0;
 	size_t mmap_size = 0;
 	int opt;
 	struct passwd *pw, pw_buf;
@@ -73,9 +72,6 @@ void ossp_slave_init(int argc, char **argv)
 		case 'm':
 			mmap_fd = strtol(optarg, NULL, 0);
 			break;
-		case 'o':
-			mmap_off = strtoull(optarg, NULL, 0);
-			break;
 		case 's':
 			mmap_size = strtoul(optarg, NULL, 0);
 			break;
@@ -104,18 +100,19 @@ void ossp_slave_init(int argc, char **argv)
 	if (mmap_fd >= 0) {
 		void *p;
 
-		if (!mmap_off || !mmap_size) {
+		if (!mmap_size) {
 			fprintf(stderr, usage);
 			_exit(1);
 		}
 
-		p = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED,
-			 mmap_fd, mmap_off);
+		p = mmap(NULL, mmap_size + 2 * sizeof(struct ossp_transfer),
+			 PROT_READ | PROT_WRITE, MAP_SHARED, mmap_fd, 0);
 		if (p == MAP_FAILED)
 			fatal_e(-errno, "mmap failed");
 
 		ossp_mmap_addr[PLAY] = p;
 		ossp_mmap_addr[REC] = p + mmap_size / 2;
+		ossp_mmap_transfer = p + mmap_size;
 		close(mmap_fd);
 	}
 

ossp-slave.h

@@ -18,6 +18,7 @@
 extern char ossp_user_name[OSSP_USER_NAME_LEN];
 extern int ossp_cmd_fd, ossp_notify_fd;
 extern void *ossp_mmap_addr[2];
+extern struct ossp_transfer *ossp_mmap_transfer;
 
 void ossp_slave_init(int argc, char **argv);
 int ossp_slave_process_command(int cmd_fd,

ossp.h

@@ -12,6 +12,7 @@
 
 #include <sys/types.h>
 #include <inttypes.h>
+#include <semaphore.h>
 #include <sys/soundcard.h>
 
 #define OSSP_VERSION		"1.3.2"
@@ -64,10 +65,18 @@ enum ossp_notify_opcode {
 	OSSP_NOTIFY_POLL,
 	OSSP_NOTIFY_OBITUARY,
 	OSSP_NOTIFY_VOLCHG,
+	OSSP_NOTIFY_FILL,
+	OSSP_NOTIFY_STORE,
 
 	OSSP_NR_NOTIFY_OPCODES,
 };
 
+struct ossp_transfer {
+	sem_t sem;
+	size_t pos;
+	size_t bytes;
+};
+
 struct ossp_mixer_arg {
 	int			vol[2][2];
 };