skill: support namespaces

In the same fashion of pgrep, introduce two new options:
	--ns <pid>
	- nslist <ns,...>
which allows processes to be filtered by namespace.

Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>

Makefile.am

@@ -55,7 +55,7 @@ EXTRA_DIST = \
 if BUILD_KILL
 bin_PROGRAMS = kill
 dist_man_MANS += kill.1
-kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
+kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
 else
   EXTRA_DIST += kill.1
 endif
@@ -77,8 +77,8 @@ if BUILD_SKILL
 usrbin_exec_PROGRAMS += \
 	skill \
 	snice
-skill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
-snice_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
+skill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
+snice_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
 dist_man_MANS += \
 	skill.1 \
 	snice.1

skill.1

@@ -77,6 +77,13 @@ The next expression is a process ID number.
 .TP
 \fB\-c\fR, \fB\-\-command\fR \fIcommand\fR
 The next expression is a command name.
+.TP
+\fB\-\-ns \fIpid\fR
+Match the processes that belong to the same namespace as pid.
+.TP
+\fB\-\-nslist \fIns,...\fR
+list which namespaces will be considered for the --ns option.
+Available namespaces: ipc, mnt, net, pid, user, uts.
 .PD
 .SH SIGNALS
 The behavior of signals is explained in

skill.c

@@ -36,6 +36,7 @@
 
 #include "c.h"
 #include "fileutils.h"
+#include "nsutils.h"
 #include "strutils.h"
 #include "nls.h"
 #include "xalloc.h"
@@ -43,6 +44,7 @@
 #include "proc/sig.h"
 #include "proc/devname.h"
 #include "proc/procps.h"	/* char *user_from_uid(uid_t uid) */
+#include "proc/readproc.h"
 #include "proc/version.h"	/* procps_version */
 #include "rpmatch.h"
 
@@ -56,11 +58,14 @@ struct run_time_conf_t {
 	int noaction;
 	int debugging;
 };
-static int tty_count, uid_count, cmd_count, pid_count;
+static int tty_count, uid_count, cmd_count, pid_count, namespace_count;
 static int *ttys;
 static uid_t *uids;
 static const char **cmds;
 static int *pids;
+static char **namespaces;
+static int ns_pid;
+static proc_t ns_task;
 
 #define ENLIST(thing,addme) do{ \
 if(!thing##s) thing##s = xmalloc(sizeof(*thing##s)*saved_argc); \
@@ -85,6 +90,39 @@ static void display_kill_version(void)
 	fprintf(stdout, PROCPS_NG_VERSION);
 }
 
+static int ns_flags = 0x3f;
+static int parse_namespaces(char *optarg)
+{
+	char *ptr = optarg, *tmp;
+	int len, id;
+
+	ns_flags = 0;
+	while (1) {
+		if (strchr(ptr, ',') == NULL) {
+			len = -1;
+			tmp = strdup(ptr);
+		} else {
+			len = strchr(ptr, ',') - ptr;
+			tmp = strndup(ptr, len);
+		}
+
+		id = get_ns_id(tmp);
+		if (id == -1) {
+			fprintf(stderr, "%s is not a valid namespace\n", tmp);
+			free(tmp);
+			return 1;
+		}
+		ns_flags |= (1 << id);
+		ENLIST(namespace, tmp);
+
+		if (len == -1)
+			break;
+
+		ptr+= len + 1;
+	}
+	return 0;
+}
+
 /* kill or nice a process */
 static void hurt_proc(int tty, int uid, int pid, const char *restrict const cmd,
 		      struct run_time_conf_t *run_time)
@@ -131,6 +169,7 @@ static void check_proc(int pid, struct run_time_conf_t *run_time)
 {
 	char buf[128];
 	struct stat statbuf;
+	proc_t task;
 	char *tmp;
 	int tty;
 	int fd;
@@ -183,6 +222,16 @@ static void check_proc(int pid, struct run_time_conf_t *run_time)
 		if (i == -1)
 			goto closure;
 	}
+	if (ns_pid) {
+		if (ns_read(pid, &task))
+			goto closure;
+		for (i = 0; i < NUM_NS; i++) {
+			if (ns_flags & (1 << i)) {
+				if (task.ns[i] != ns_task.ns[i])
+					goto closure;
+			}
+		}
+	}
 	/* This is where we kill/nice something. */
 	/* for debugging purposes?
 	fprintf(stderr, "PID %d, UID %d, TTY %d,%d, COMM %s\n",
@@ -317,6 +366,15 @@ static void __attribute__ ((__noreturn__)) skillsnice_usage(FILE * out)
 		" -t, --tty <tty>          expression is a terminal\n"
 		" -u, --user <username>    expression is a username\n"), out);
 	fputs(USAGE_SEPARATOR, out);
+	fputs(_("Alternatively, expression can be:\n"
+		" --ns <pid>               match the processes that belong to the same\n"
+		"                          namespace as <pid>\n"
+		" --nslist <ns,...>        list which namespaces will be considered for\n"
+		"                          the --ns option.\n"
+		"                          Available namespaces: ipc, mnt, net, pid, user, uts\n"), out);
+
+	fputs(USAGE_SEPARATOR, out);
+	fputs(USAGE_SEPARATOR, out);
 	fputs(USAGE_HELP, out);
 	fputs(USAGE_VERSION, out);
 	if (program == PROG_SKILL) {
@@ -488,6 +546,11 @@ static void skillsnice_parse(int argc,
 	int prino = DEFAULT_NICE;
 	int ch, i;
 
+	enum {
+		NS_OPTION = CHAR_MAX + 1,
+		NSLIST_OPTION,
+	};
+
 	static const struct option longopts[] = {
 		{"command", required_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 'd'},
@@ -499,6 +562,8 @@ static void skillsnice_parse(int argc,
 		{"table", no_argument, NULL, 'L'},
 		{"tty", required_argument, NULL, 't'},
 		{"user", required_argument, NULL, 'u'},
+		{"ns", required_argument, NULL, NS_OPTION},
+		{"nslist", required_argument, NULL, NSLIST_OPTION},
 		{"verbose", no_argument, NULL, 'v'},
 		{"warnings", no_argument, NULL, 'w'},
 		{"help", no_argument, NULL, 'h'},
@@ -572,6 +637,25 @@ static void skillsnice_parse(int argc,
 				}
 			}
 			break;
+		case NS_OPTION:
+			ns_pid = atoi(optarg);
+			if (ns_pid == 0) {
+				xwarnx(_("invalid pid number %i"), optarg);
+				kill_usage(stderr);
+			}
+			if (ns_read(ns_pid, &ns_task)) {
+				xwarnx(_("error reading reference namespace "
+					 "information"));
+				kill_usage(stderr);
+			}	
+
+			break;
+		case NSLIST_OPTION:
+			if (parse_namespaces(optarg)) {
+				xwarnx(_("invalid namespace list"));
+				kill_usage(stderr);
+			}
+			break;
 		case 'v':
 			run_time->verbose = 1;
 			break;
@@ -605,7 +689,7 @@ static void skillsnice_parse(int argc,
 	}
 
 	/* No more arguments to process. Must sanity check. */
-	if (!tty_count && !uid_count && !cmd_count && !pid_count)
+	if (!tty_count && !uid_count && !cmd_count && !pid_count && !ns_pid)
 		xerrx(EXIT_FAILURE, _("no process selection criteria"));
 	if ((run_time->fast | run_time->interactive | run_time->
 	     verbose | run_time->warnings | run_time->noaction) & ~1)