Add procstat_getgroups function to retrieve process groups.

MFC after:	1 month

lib/libprocstat/Symbol.map

@@ -16,8 +16,10 @@ FBSD_1.2 {
 };
 
 FBSD_1.3 {
+	procstat_freegroups;
 	procstat_freevmmap;
 	procstat_get_shm_info;
+	procstat_getgroups;
 	procstat_getvmmap;
 	procstat_open_core;
 };

lib/libprocstat/core.c

@@ -167,6 +167,10 @@ procstat_core_get(struct procstat_core *core, enum psc_type type, void *buf,
 		n_type = NT_PROCSTAT_VMMAP;
 		structsize = sizeof(struct kinfo_vmentry);
 		break;
+	case PSC_TYPE_GROUPS:
+		n_type = NT_PROCSTAT_GROUPS;
+		structsize = sizeof(gid_t);
+		break;
 	default:
 		warnx("unknown core stat type: %d", type);
 		return (NULL);

lib/libprocstat/core.h

@@ -33,6 +33,7 @@ enum psc_type {
 	PSC_TYPE_PROC,
 	PSC_TYPE_FILES,
 	PSC_TYPE_VMMAP,
+	PSC_TYPE_GROUPS,
 };
 
 struct procstat_core;

lib/libprocstat/libprocstat.3

@@ -33,9 +33,11 @@
 .Nm procstat_open_sysctl ,
 .Nm procstat_close ,
 .Nm procstat_getfiles ,
+.Nm procstat_getgroups ,
 .Nm procstat_getprocs ,
 .Nm procstat_getvmmap ,
 .Nm procstat_freefiles ,
+.Nm procstat_freegroups ,
 .Nm procstat_freeprocs ,
 .Nm procstat_freevmmap ,
 .Nm procstat_get_pipe_info ,
@@ -52,12 +54,18 @@
 .In libprocstat.h
 .Ft void
 .Fn procstat_close "struct procstat *procstat"
+.Fc
 .Ft void
 .Fo procstat_freefiles
 .Fa "struct procstat *procstat"
 .Fa "struct filestat_list *head"
 .Fc
 .Ft void
+.Fo procstat_freegroups
+.Fa "struct procstat *procstat"
+.Fa "gid_t *groups"
+.Fc
+.Ft void
 .Fn procstat_freeprocs "struct procstat *procstat" "struct kinfo_proc *p"
 .Ft void
 .Fo procstat_freevmmap
@@ -105,6 +113,12 @@
 .Fa "struct kinfo_proc *kp"
 .Fa "int mmapped"
 .Fc
+.Ft "gid_t *"
+.Fo procstat_getgroups
+.Fa "struct procstat *procstat"
+.Fa "struct kinfo_proc *kp"
+.Fa "unsigned int *count"
+.Fc
 .Ft "struct kinfo_proc *"
 .Fo procstat_getprocs
 .Fa "struct procstat *procstat"
@@ -227,6 +241,19 @@ The caller is responsible to free the allocated memory with a subsequent
 function call.
 .Pp
 The
+.Fn procstat_getgroups
+function gets a pointer to the
+.Vt procstat
+structure, a pointer to
+.Vt kinfo_proc
+structure, and returns the process groups as a dynamically allocated array of
+.Vt gid_t
+elements.
+The caller is responsible to free the allocated memory with a subsequent
+.Fn procstat_freegroups
+function call.
+.Pp
+The
 .Fn procstat_getvmmap
 function gets a pointer to the
 .Vt procstat

lib/libprocstat/libprocstat.c

@@ -132,6 +132,9 @@ static int	procstat_get_vnode_info_kvm(kvm_t *kd, struct filestat *fst,
     struct vnstat *vn, char *errbuf);
 static int	procstat_get_vnode_info_sysctl(struct filestat *fst,
     struct vnstat *vn, char *errbuf);
+static gid_t	*procstat_getgroups_core(struct procstat_core *core,
+    unsigned int *count);
+static gid_t	*procstat_getgroups_sysctl(pid_t pid, unsigned int *count);
 static int	vntype2psfsttype(int type);
 
 void
@@ -1588,3 +1591,67 @@ procstat_freevmmap(struct procstat *procstat __unused,
 
 	free(vmmap);
 }
+
+static gid_t *
+procstat_getgroups_sysctl(pid_t pid, unsigned int *cntp)
+{
+	int mib[4];
+	size_t len;
+	gid_t *groups;
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_PROC;
+	mib[2] = KERN_PROC_GROUPS;
+	mib[3] = pid;
+	len = (sysconf(_SC_NGROUPS_MAX) + 1) * sizeof(gid_t);
+	groups = malloc(len);
+	if (groups == NULL) {
+		warn("malloc(%zu)", len);
+		return (NULL);
+	}
+	if (sysctl(mib, 4, groups, &len, NULL, 0) == -1) {
+		warn("sysctl: kern.proc.groups: %d", pid);
+		free(groups);
+		return (NULL);
+	}
+	*cntp = len / sizeof(gid_t);
+	return (groups);
+}
+
+static gid_t *
+procstat_getgroups_core(struct procstat_core *core, unsigned int *cntp)
+{
+	size_t len;
+	gid_t *groups;
+
+	groups = procstat_core_get(core, PSC_TYPE_GROUPS, NULL, &len);
+	if (groups == NULL)
+		return (NULL);
+	*cntp = len / sizeof(gid_t);
+	return (groups);
+}
+
+gid_t *
+procstat_getgroups(struct procstat *procstat, struct kinfo_proc *kp,
+    unsigned int *cntp)
+{
+	switch(procstat->type) {
+	case PROCSTAT_KVM:
+		warnx("kvm method is not supported");
+		return (NULL);
+	case PROCSTAT_SYSCTL:
+		return (procstat_getgroups_sysctl(kp->ki_pid, cntp));
+	case PROCSTAT_CORE:
+		return (procstat_getgroups_core(procstat->core, cntp));
+	default:
+		warnx("unknown access method: %d", procstat->type);
+		return (NULL);
+	}
+}
+
+void
+procstat_freegroups(struct procstat *procstat __unused, gid_t *groups)
+{
+
+	free(groups);
+}

lib/libprocstat/libprocstat.h

@@ -146,6 +146,7 @@ STAILQ_HEAD(filestat_list, filestat);
 
 __BEGIN_DECLS
 void	procstat_close(struct procstat *procstat);
+void	procstat_freegroups(struct procstat *procstat, gid_t *groups);
 void	procstat_freeprocs(struct procstat *procstat, struct kinfo_proc *p);
 void	procstat_freefiles(struct procstat *procstat,
     struct filestat_list *head);
@@ -165,6 +166,8 @@ int	procstat_get_socket_info(struct procstat *procstat, struct filestat *fst,
     struct sockstat *sock, char *errbuf);
 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);
 struct kinfo_vmentry	*procstat_getvmmap(struct procstat *procstat,
     struct kinfo_proc *kp, unsigned int *count);
 struct procstat	*procstat_open_core(const char *filename);