Add procstat_getosrel function to retrieve a process osrel info.

MFC after:	1 month

lib/libprocstat/Symbol.map

@@ -20,6 +20,7 @@ FBSD_1.3 {
 	procstat_freevmmap;
 	procstat_get_shm_info;
 	procstat_getgroups;
+	procstat_getosrel;
 	procstat_getpathname;
 	procstat_getrlimit;
 	procstat_getumask;

lib/libprocstat/core.c

@@ -179,6 +179,10 @@ procstat_core_get(struct procstat_core *core, enum psc_type type, void *buf,
 		n_type = NT_PROCSTAT_RLIMIT;
 		structsize = sizeof(struct rlimit) * RLIM_NLIMITS;
 		break;
+	case PSC_TYPE_OSREL:
+		n_type = NT_PROCSTAT_OSREL;
+		structsize = sizeof(int);
+		break;
 	default:
 		warnx("unknown core stat type: %d", type);
 		return (NULL);

lib/libprocstat/core.h

@@ -36,6 +36,7 @@ enum psc_type {
 	PSC_TYPE_GROUPS,
 	PSC_TYPE_UMASK,
 	PSC_TYPE_RLIMIT,
+	PSC_TYPE_OSREL,
 };
 
 struct procstat_core;

lib/libprocstat/libprocstat.3

@@ -34,6 +34,7 @@
 .Nm procstat_close ,
 .Nm procstat_getfiles ,
 .Nm procstat_getgroups ,
+.Nm procstat_getosrel ,
 .Nm procstat_getpathname ,
 .Nm procstat_getprocs ,
 .Nm procstat_getumask ,
@@ -120,6 +121,11 @@
 .Fa "struct procstat *procstat"
 .Fa "struct kinfo_proc *kp"
 .Fa "unsigned int *count"
+.Ft int
+.Fo procstat_getosrel
+.Fa "struct procstat *procstat"
+.Fa "struct kinfo_proc *kp"
+.Fa "int *osrelp"
 .Fc
 .Ft "struct kinfo_proc *"
 .Fo procstat_getprocs
@@ -276,6 +282,14 @@ The caller is responsible to free the allocated memory with a subsequent
 function call.
 .Pp
 The
+.Fn procstat_getosrel
+function gets a pointer to the
+.Vt procstat
+structure, a pointer to
+.Vt kinfo_proc
+structure, and returns osrel date in the 3rd reference parameter.
+.Pp
+The
 .Fn procstat_getpathname
 function gets a pointer to the
 .Vt procstat

lib/libprocstat/libprocstat.c

@@ -1845,3 +1845,55 @@ procstat_getpathname(struct procstat *procstat, struct kinfo_proc *kp,
 		return (-1);
 	}
 }
+
+static int
+procstat_getosrel_sysctl(pid_t pid, int *osrelp)
+{
+	int error, name[4];
+	size_t len;
+
+	name[0] = CTL_KERN;
+	name[1] = KERN_PROC;
+	name[2] = KERN_PROC_OSREL;
+	name[3] = pid;
+	len = sizeof(*osrelp);
+	error = sysctl(name, 4, osrelp, &len, NULL, 0);
+	if (error != 0 && errno != ESRCH)
+		warn("sysctl: kern.proc.osrel: %d", pid);
+	return (error);
+}
+
+static int
+procstat_getosrel_core(struct procstat_core *core, int *osrelp)
+{
+	size_t len;
+	int *buf;
+
+	buf = procstat_core_get(core, PSC_TYPE_OSREL, NULL, &len);
+	if (buf == NULL)
+		return (-1);
+	if (len < sizeof(*osrelp)) {
+		free(buf);
+		return (-1);
+	}
+	*osrelp = *buf;
+	free(buf);
+	return (0);
+}
+
+int
+procstat_getosrel(struct procstat *procstat, struct kinfo_proc *kp, int *osrelp)
+{
+	switch(procstat->type) {
+	case PROCSTAT_KVM:
+		warnx("kvm method is not supported");
+		return (-1);
+	case PROCSTAT_SYSCTL:
+		return (procstat_getosrel_sysctl(kp->ki_pid, osrelp));
+	case PROCSTAT_CORE:
+		return (procstat_getosrel_core(procstat->core, osrelp));
+	default:
+		warnx("unknown access method: %d", procstat->type);
+		return (-1);
+	}
+}

lib/libprocstat/libprocstat.h

@@ -169,6 +169,8 @@ int	procstat_get_vnode_info(struct procstat *procstat, struct filestat *fst,
     struct vnstat *vn, char *errbuf);
 gid_t	*procstat_getgroups(struct procstat *procstat, struct kinfo_proc *kp,
     unsigned int *count);
+int	procstat_getosrel(struct procstat *procstat, struct kinfo_proc *kp,
+    int *osrelp);
 int	procstat_getpathname(struct procstat *procstat, struct kinfo_proc *kp,
     char *pathname, size_t maxlen);
 int	procstat_getrlimit(struct procstat *procstat, struct kinfo_proc *kp,