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

4 files changed, 110 insertions, 1 deletions

diff --git a/lib/libprocstat/Symbol.map b/lib/libprocstat/Symbol.map
index 085720c..1495bfc 100644
--- a/lib/libprocstat/Symbol.map
+++ b/lib/libprocstat/Symbol.map
@@ -22,6 +22,7 @@ FBSD_1.3 {
 	procstat_freegroups;
 	procstat_freekstack;
 	procstat_freevmmap;
+	procstat_get_sem_info;
 	procstat_get_shm_info;
 	procstat_getargv;
 	procstat_getauxv;
diff --git a/lib/libprocstat/libprocstat.3 b/lib/libprocstat/libprocstat.3
index 3312427..e82c30a 100644
--- a/lib/libprocstat/libprocstat.3
+++ b/lib/libprocstat/libprocstat.3
@@ -53,6 +53,7 @@
 .Nm procstat_freevmmap ,
 .Nm procstat_get_pipe_info ,
 .Nm procstat_get_pts_info ,
+.Nm procstat_get_sem_info ,
 .Nm procstat_get_shm_info ,
 .Nm procstat_get_socket_info ,
 .Nm procstat_get_vnode_info
@@ -115,6 +116,13 @@
 .Fa "char *errbuf"
 .Fc
 .Ft int
+.Fo procstat_get_sem_info
+.Fa "struct procstat *procstat"
+.Fa "struct filestat *fst"
+.Fa "struct semstat *sem"
+.Fa "char *errbuf"
+.Fc
+.Ft int
 .Fo procstat_get_shm_info
 .Fa "struct procstat *procstat"
 .Fa "struct filestat *fst"
@@ -463,12 +471,13 @@ function call.
 The
 .Fn procstat_get_pipe_info ,
 .Fn procstat_get_pts_info ,
+.Fn procstat_get_sem_info ,
 .Fn procstat_get_shm_info ,
 .Fn procstat_get_socket_info
 and
 .Fn procstat_get_vnode_info
 functions are used to retrieve information about pipes, pseudo-terminals,
-shared memory objects,
+semaphores, shared memory objects,
 sockets, and vnodes, respectively.
 Each of them have a similar interface API.
 The
@@ -505,6 +514,8 @@ argument indicates an actual error message in case of failure.
 .Nm procstat_get_pipe_info
 .It Li PS_FST_TYPE_PTS
 .Nm procstat_get_pts_info
+.It Li PS_FST_TYPE_SEM
+.Nm procstat_get_sem_info
 .It Li PS_FST_TYPE_SHM
 .Nm procstat_get_shm_info
 .El
@@ -517,6 +528,7 @@ argument indicates an actual error message in case of failure.
 .Xr elf 3 ,
 .Xr kvm 3 ,
 .Xr queue 3 ,
+.Xr sem_open 3 ,
 .Xr sysctl 3 ,
 .Xr pts 4 ,
 .Xr core 5 ,
diff --git a/lib/libprocstat/libprocstat.c b/lib/libprocstat/libprocstat.c
index dd16c80..78eae9f 100644
--- a/lib/libprocstat/libprocstat.c
+++ b/lib/libprocstat/libprocstat.c
@@ -59,6 +59,7 @@ __FBSDID("$FreeBSD$");
 #define	_WANT_FILE
 #include <sys/file.h>
 #include <sys/conf.h>
+#include <sys/ksem.h>
 #include <sys/mman.h>
 #define	_KERNEL
 #include <sys/mount.h>
@@ -129,6 +130,10 @@ static int	procstat_get_pts_info_sysctl(struct filestat *fst,
     struct ptsstat *pts, char *errbuf);
 static int	procstat_get_pts_info_kvm(kvm_t *kd, struct filestat *fst,
     struct ptsstat *pts, char *errbuf);
+static int	procstat_get_sem_info_sysctl(struct filestat *fst,
+    struct semstat *sem, char *errbuf);
+static int	procstat_get_sem_info_kvm(kvm_t *kd, struct filestat *fst,
+    struct semstat *sem, char *errbuf);
 static int	procstat_get_shm_info_sysctl(struct filestat *fst,
     struct shmstat *shm, char *errbuf);
 static int	procstat_get_shm_info_kvm(kvm_t *kd, struct filestat *fst,
@@ -556,6 +561,10 @@ procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmap
 			data = file.f_data;
 			break;
 #endif
+		case DTYPE_SEM:
+			type = PS_FST_TYPE_SEM;
+			data = file.f_data;
+			break;
 		case DTYPE_SHM:
 			type = PS_FST_TYPE_SHM;
 			data = file.f_data;
@@ -1003,6 +1012,87 @@ procstat_get_pts_info_sysctl(struct filestat *fst, struct ptsstat *pts,
 }
 
 int
+procstat_get_sem_info(struct procstat *procstat, struct filestat *fst,
+    struct semstat *sem, char *errbuf)
+{
+
+	assert(sem);
+	if (procstat->type == PROCSTAT_KVM) {
+		return (procstat_get_sem_info_kvm(procstat->kd, fst, sem,
+		    errbuf));
+	} else if (procstat->type == PROCSTAT_SYSCTL ||
+	    procstat->type == PROCSTAT_CORE) {
+		return (procstat_get_sem_info_sysctl(fst, sem, errbuf));
+	} else {
+		warnx("unknown access method: %d", procstat->type);
+		snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+		return (1);
+	}
+}
+
+static int
+procstat_get_sem_info_kvm(kvm_t *kd, struct filestat *fst,
+    struct semstat *sem, char *errbuf)
+{
+	struct ksem ksem;
+	void *ksemp;
+	char *path;
+	int i;
+
+	assert(kd);
+	assert(sem);
+	assert(fst);
+	bzero(sem, sizeof(*sem));
+	ksemp = fst->fs_typedep;
+	if (ksemp == NULL)
+		goto fail;
+	if (!kvm_read_all(kd, (unsigned long)ksemp, &ksem,
+	    sizeof(struct ksem))) {
+		warnx("can't read ksem at %p", (void *)ksemp);
+		goto fail;
+	}
+	sem->mode = S_IFREG | ksem.ks_mode;
+	sem->value = ksem.ks_value;
+	if (fst->fs_path == NULL && ksem.ks_path != NULL) {
+		path = malloc(MAXPATHLEN);
+		for (i = 0; i < MAXPATHLEN - 1; i++) {
+			if (!kvm_read_all(kd, (unsigned long)ksem.ks_path + i,
+			    path + i, 1))
+				break;
+			if (path[i] == '\0')
+				break;
+		}
+		path[i] = '\0';
+		if (i == 0)
+			free(path);
+		else
+			fst->fs_path = path;
+	}
+	return (0);
+
+fail:
+	snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+	return (1);
+}
+
+static int
+procstat_get_sem_info_sysctl(struct filestat *fst, struct semstat *sem,
+    char *errbuf __unused)
+{
+	struct kinfo_file *kif;
+
+	assert(sem);
+	assert(fst);
+	bzero(sem, sizeof(*sem));
+	kif = fst->fs_typedep;
+	if (kif == NULL)
+		return (0);
+	sem->value = kif->kf_un.kf_sem.kf_sem_value;
+	sem->mode = kif->kf_un.kf_sem.kf_sem_mode;
+	return (0);
+}
+
+int
 procstat_get_shm_info(struct procstat *procstat, struct filestat *fst,
     struct shmstat *shm, char *errbuf)
 {
diff --git a/lib/libprocstat/libprocstat.h b/lib/libprocstat/libprocstat.h
index 2c2662d..65a5eb9 100644
--- a/lib/libprocstat/libprocstat.h
+++ b/lib/libprocstat/libprocstat.h
@@ -133,6 +133,10 @@ struct pipestat {
 	uint64_t	addr;
 	uint64_t	peer;
 };
+struct semstat {
+	uint32_t	value;
+	uint16_t	mode;
+};
 struct shmstat {
 	uint64_t	size;
 	uint16_t	mode;
@@ -177,6 +181,8 @@ int	procstat_get_pipe_info(struct procstat *procstat, struct filestat *fst,
     struct pipestat *pipe, char *errbuf);
 int	procstat_get_pts_info(struct procstat *procstat, struct filestat *fst,
     struct ptsstat *pts, char *errbuf);
+int	procstat_get_sem_info(struct procstat *procstat, struct filestat *fst,
+    struct semstat *sem, char *errbuf);
 int	procstat_get_shm_info(struct procstat *procstat, struct filestat *fst,
     struct shmstat *shm, char *errbuf);
 int	procstat_get_socket_info(struct procstat *procstat, struct filestat *fst,