add sem_create(), wrappign sem_init() for linux and sem_open() for macOS

src/mscp.c

@@ -204,24 +204,9 @@ static int validate_and_set_defaut_params(struct mscp_opts *o)
 	return 0;
 }
 
-static int random_string(char *buf, size_t size)
-{
-	char chars[] = "abcdefhijklmnopkwxyz1234567890";
-	int n, x;
-
-	for (n = 0; n < size - 1; n++) {
-		x = get_random(sizeof(chars) - 1);
-		buf[n] = chars[x];
-	}
-	buf[size - 1] = '\0';
-
-	return 0;
-}
-
 struct mscp *mscp_init(const char *remote_host, int direction,
 		       struct mscp_opts *o, struct mscp_ssh_opts *s)
 {
-	char sem_name[PSEMNAMLEN] = "mscp-";
 	struct mscp *m;
 	int n;
 
@@ -253,12 +238,8 @@ struct mscp *mscp_init(const char *remote_host, int direction,
 	INIT_LIST_HEAD(&m->path_list);
 	chunk_pool_init(&m->cp);
 
-	n = strlen(sem_name);
-	if (random_string(sem_name + n, sizeof(sem_name) - n - 1) < 0)
-		goto free_out;
-
-	if ((m->sem = sem_open(sem_name, O_CREAT, 600, o->max_startups)) == SEM_FAILED) {
-		mscp_set_error("sem_open: %s", strerrno());
+	if ((m->sem = sem_create(o->max_startups)) == NULL) {
+		mscp_set_error("sem_create: %s", strerrno());
 		goto free_out;
 	}
 
@@ -708,7 +689,8 @@ void mscp_free(struct mscp *m)
 		free(m->remote);
 	if (m->cores)
 		free(m->cores);
-	sem_close(m->sem);
+
+	sem_release(m->sem);
 	free(m);
 }
 

src/platform.c

@@ -1,19 +1,20 @@
 #ifdef __APPLE__
+#include <stdlib.h>
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #elif linux
 #define _GNU_SOURCE
 #include <sched.h>
+#include <stdlib.h>
 #else
 #error unsupported platform
 #endif
 
-#include <stdlib.h>
-
 #include <util.h>
 #include <platform.h>
 #include <message.h>
 
+
 #ifdef __APPLE__
 int nr_cpus()
 {
@@ -34,9 +35,38 @@ int set_thread_affinity(pthread_t tid, int core)
 	return 0;
 }
 
-int get_random(int max)
+
+static void random_string(char *buf, size_t size)
 {
-	return arc4random() % max;
+        char chars[] = "abcdefhijklmnopkwxyz1234567890";
+        int n, x;
+
+        for (n = 0; n < size - 1; n++) {
+                x = arc4random(sizeof(chars) - 1);
+                buf[n] = chars[x];
+        }
+        buf[size - 1] = '\0';
+
+        return 0;
+}
+
+sem_t *sem_create(int value)
+{
+	char sem_name[PSEMNAMLEN] = "mscp-";
+	sem_t *sem;
+	int n;
+
+        n = strlen(sem_name);
+        random_string(sem_name + n, sizeof(sem_name) - n - 1);
+        if ((sem = sem_open(sem_name, O_CREAT, 600, value)) == SEM_FAILED)
+	    return NULL;
+
+	return sem;
+}
+
+int sem_release(sem_t *sem)
+{
+	return sem_close(sem);
 }
 
 #endif
@@ -64,9 +94,27 @@ int set_thread_affinity(pthread_t tid, int core)
 	return ret;
 }
 
-int get_random(int max)
+sem_t *sem_create(int value)
 {
-	return random() % max;
+	sem_t *sem;
+
+	if ((sem = malloc(sizeof(*sem))) == NULL)
+		return NULL;
+
+	if (sem_init(sem, 0, value) < 0) {
+		free(sem);
+		return sem;
+	}
+
+	return sem;
 }
+
+int sem_release(sem_t *sem)
+{
+	int ret = sem_close(sem);
+	free(sem);
+	return ret;
+}
+
 #endif
 

src/platform.h

@@ -2,13 +2,20 @@
 #define _PLATFORM_H_
 
 #include <pthread.h>
-
-#ifndef PSEMNAMLEN	/* defined in macOS, but not in Linux */
-#define PSEMNAMLEN	31
-#endif
+#include <semaphore.h>
 
 int nr_cpus(void);
 int set_thread_affinity(pthread_t tid, int core);
-int get_random(int max);
+
+/*
+ * macOS does not support sem_init(). macOS (seems to) releases the
+ * named semaphore when associated mscp process finished. In linux,
+ * program (seems to) need to release named semaphore in /dev/shm by
+ * sem_unlink() explicitly. So, using sem_init() (unnamed semaphore)
+ * in linux and using sem_open() (named semaphore) in macOS without
+ * sem_unlink() are reasonable (?).
+ */
+sem_t *sem_create(int value);
+int sem_release(sem_t *sem);
 
 #endif /* _PLATFORM_H_ */