Export some more useful info about shared memory objects to userland

via procstat(1) and fstat(1):
- Change shm file descriptors to track the pathname they are associated
  with and add a shm_path() method to copy the path out to a caller-supplied
  buffer.
- Use the fo_stat() method of shared memory objects and shm_path() to
  export the path, mode, and size of a shared memory object via
  struct kinfo_file.
- Add a struct shmstat to the libprocstat(3) interface along with a
  procstat_get_shm_info() to export the mode and size of a shared memory
  object.
- Change procstat to always print out the path for a given object if it
  is valid.
- Teach fstat about shared memory objects and to display their path,
  mode, and size.

MFC after:	2 weeks

1 files changed, 72 insertions, 0 deletions

diff --git a/lib/libprocstat/libprocstat.c b/lib/libprocstat/libprocstat.c
index facce11..167d91a 100644
--- a/lib/libprocstat/libprocstat.c
+++ b/lib/libprocstat/libprocstat.c
@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 #define	_WANT_FILE
 #include <sys/file.h>
 #include <sys/conf.h>
+#include <sys/mman.h>
 #define	_KERNEL
 #include <sys/mount.h>
 #include <sys/pipe.h>
@@ -114,6 +115,10 @@ 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_shm_info_sysctl(struct filestat *fst,
+    struct shmstat *shm, char *errbuf);
+static int	procstat_get_shm_info_kvm(kvm_t *kd, struct filestat *fst,
+    struct shmstat *shm, char *errbuf);
 static int	procstat_get_socket_info_sysctl(struct filestat *fst,
     struct sockstat *sock, char *errbuf);
 static int	procstat_get_socket_info_kvm(kvm_t *kd, struct filestat *fst,
@@ -469,6 +474,10 @@ procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmap
 			data = file.f_data;
 			break;
 #endif
+		case DTYPE_SHM:
+			type = PS_FST_TYPE_SHM;
+			data = file.f_data;
+			break;
 		default:
 			continue;
 		}
@@ -849,6 +858,69 @@ procstat_get_pts_info_sysctl(struct filestat *fst, struct ptsstat *pts,
 }
 
 int
+procstat_get_shm_info(struct procstat *procstat, struct filestat *fst,
+    struct shmstat *shm, char *errbuf)
+{
+
+	assert(shm);
+	if (procstat->type == PROCSTAT_KVM) {
+		return (procstat_get_shm_info_kvm(procstat->kd, fst, shm,
+		    errbuf));
+	} else if (procstat->type == PROCSTAT_SYSCTL) {
+		return (procstat_get_shm_info_sysctl(fst, shm, errbuf));
+	} else {
+		warnx("unknown access method: %d", procstat->type);
+		snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+		return (1);
+	}
+}
+
+static int
+procstat_get_shm_info_kvm(kvm_t *kd, struct filestat *fst,
+    struct shmstat *shm, char *errbuf)
+{
+	struct shmfd shmfd;
+	void *shmfdp;
+
+	assert(kd);
+	assert(shm);
+	assert(fst);
+	bzero(shm, sizeof(*shm));
+	shmfdp = fst->fs_typedep;
+	if (shmfdp == NULL)
+		goto fail;
+	if (!kvm_read_all(kd, (unsigned long)shmfdp, &shmfd,
+	    sizeof(struct shmfd))) {
+		warnx("can't read shmfd at %p", (void *)shmfdp);
+		goto fail;
+	}
+	shm->mode = S_IFREG | shmfd.shm_mode;
+	shm->size = shmfd.shm_size;
+	return (0);
+
+fail:
+	snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+	return (1);
+}
+
+static int
+procstat_get_shm_info_sysctl(struct filestat *fst, struct shmstat *shm,
+    char *errbuf __unused)
+{
+	struct kinfo_file *kif;
+
+	assert(shm);
+	assert(fst);
+	bzero(shm, sizeof(*shm));
+	kif = fst->fs_typedep;
+	if (kif == NULL)
+		return (0);
+	shm->size = kif->kf_un.kf_file.kf_file_size;
+	shm->mode = kif->kf_un.kf_file.kf_file_mode;
+	return (0);
+}
+
+int
 procstat_get_vnode_info(struct procstat *procstat, struct filestat *fst,
     struct vnstat *vn, char *errbuf)
 {