Similar to 233760 and 236717, export some more useful info about the

kernel-based POSIX semaphore descriptors to userland via procstat(1) and
fstat(1):
- Change sem file descriptors to track the pathname they are associated
  with and add a ksem_info() method to copy the path out to a
  caller-supplied buffer.
- Use the fo_stat() method of shared memory objects and ksem_info() to
  export the path, mode, and value of a semaphore via struct kinfo_file.
- Add a struct semstat to the libprocstat(3) interface along with a
  procstat_get_sem_info() to export the mode and value of a semaphore.
- Teach fstat about semaphores and to display their path, mode, and value.

MFC after:	2 weeks

2 files changed, 31 insertions, 0 deletions

diff --git a/usr.bin/fstat/fstat.1 b/usr.bin/fstat/fstat.1
index 7403a8e725ee2..268b70f4526f7 100644
--- a/usr.bin/fstat/fstat.1
+++ b/usr.bin/fstat/fstat.1
@@ -155,6 +155,8 @@ using a symbolic format (see
 otherwise, the mode is printed
 as an octal number.
 .It Li SZ\&|DV
+If the file is a semaphore,
+prints the current value of the semaphore.
 If the file is not a character or block special, prints the size of
 the file in bytes.
 Otherwise, if the
diff --git a/usr.bin/fstat/fstat.c b/usr.bin/fstat/fstat.c
index 265791d1daacf..1aeee67511dd7 100644
--- a/usr.bin/fstat/fstat.c
+++ b/usr.bin/fstat/fstat.c
@@ -84,6 +84,8 @@ static void	print_pipe_info(struct procstat *procstat,
     struct filestat *fst);
 static void	print_pts_info(struct procstat *procstat,
     struct filestat *fst);
+static void	print_sem_info(struct procstat *procstat,
+    struct filestat *fst);
 static void	print_shm_info(struct procstat *procstat,
     struct filestat *fst);
 static void	print_socket_info(struct procstat *procstat,
@@ -294,6 +296,9 @@ print_file_info(struct procstat *procstat, struct filestat *fst,
 	case PS_FST_TYPE_SHM:
 		print_shm_info(procstat, fst);
 		break;
+	case PS_FST_TYPE_SEM:
+		print_sem_info(procstat, fst);
+		break;
 	default:	
 		if (vflg)
 			fprintf(stderr,
@@ -424,6 +429,30 @@ print_pts_info(struct procstat *procstat, struct filestat *fst)
 }
 
 static void
+print_sem_info(struct procstat *procstat, struct filestat *fst)
+{
+	struct semstat sem;
+	char errbuf[_POSIX2_LINE_MAX];
+	char mode[15];
+	int error;
+
+	error = procstat_get_sem_info(procstat, fst, &sem, errbuf);
+	if (error != 0) {
+		printf("* error");
+		return;
+	}
+	if (nflg) {
+		printf("             ");
+		(void)snprintf(mode, sizeof(mode), "%o", sem.mode);
+	} else {
+		printf(" %-15s", fst->fs_path != NULL ? fst->fs_path : "-");
+		strmode(sem.mode, mode);
+	}
+	printf(" %10s %6u", mode, sem.value);
+	print_access_flags(fst->fs_fflags);
+}
+
+static void
 print_shm_info(struct procstat *procstat, struct filestat *fst)
 {
 	struct shmstat shm;