unshare: Allow passing <signame> to --kill-child

diff --git a/sys-utils/unshare.1 b/sys-utils/unshare.1
index 420b48b73c6d03e025f6515baea27aa78d431454..65dc55ce9ac53ecc282fc52a6a2821f0f437a53f 100644 (file)
--- a/sys-utils/unshare.1
+++ b/sys-utils/unshare.1
@@ -138,10 +138,11 @@ by bind mount.
 Fork the specified \fIprogram\fR as a child process of \fBunshare\fR rather than
 running it directly.  This is useful when creating a new PID namespace.
 .TP
-.BR \-\-kill\-child
-When \fBunshare\fR terminates, have \fBSIGKILL\fR be sent to the forked child process.
+.BR \-\-kill\-child [ =\fIsigname ]
+When \fBunshare\fR terminates, have \fIsigname\fP be sent to the forked child process.
 Combined with \fB--pid\fR this allows for an easy and realiable killing of the entire
 process tree below \fBunshare\fR.
+If not given, \fIsigname\fP defaults to \fBSIGKILL\fR.
 This option implies \fB--fork\fR.
 .TP
 .BR \-\-mount\-proc [ =\fImountpoint ]

diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
index b7448420ba988848c378482cbf051f20cf08a7b0..00afc7dd8ae6d1b1862843929124ebc1f190c32c 100644 (file)
--- a/sys-utils/unshare.c
+++ b/sys-utils/unshare.c
@@ -41,6 +41,7 @@
 #include "xalloc.h"
 #include "pathnames.h"
 #include "all-io.h"
+#include "signames.h"
 
 /* synchronize parent and child by pipe */
 #define PIPE_SYNC_BYTE 0x06
@@ -259,7 +260,7 @@ static void __attribute__((__noreturn__)) usage(void)
        fputs(_(" -U, --user[=<file>]       unshare user namespace\n"), out);
        fputs(_(" -C, --cgroup[=<file>]     unshare cgroup namespace\n"), out);
        fputs(_(" -f, --fork                fork before launching <program>\n"), out);
-       fputs(_("     --kill-child          when dying, kill the forked child (implies --fork)\n"), out);
+       fputs(_("     --kill-child[=<signame>]  when dying, kill the forked child (implies --fork); defaults to SIGKILL\n"), out);
        fputs(_("     --mount-proc[=<dir>]  mount proc filesystem first (implies --mount)\n"), out);
        fputs(_(" -r, --map-root-user       map current user to root (implies --user)\n"), out);
        fputs(_("     --propagation slave|shared|private|unchanged\n"
@@ -294,7 +295,7 @@ int main(int argc, char *argv[])
                { "cgroup",        optional_argument, NULL, 'C'             },
 
                { "fork",          no_argument,       NULL, 'f'             },
-               { "kill-child",    no_argument,       NULL, OPT_KILLCHILD   },
+               { "kill-child",    optional_argument, NULL, OPT_KILLCHILD   },
                { "mount-proc",    optional_argument, NULL, OPT_MOUNTPROC   },
                { "map-root-user", no_argument,       NULL, 'r'             },
                { "propagation",   required_argument, NULL, OPT_PROPAGATION },
@@ -305,7 +306,7 @@ int main(int argc, char *argv[])
        int setgrpcmd = SETGROUPS_NONE;
        int unshare_flags = 0;
        int c, forkit = 0, maproot = 0;
-       int kill_child = 0;
+       int kill_child_signo = 0; /* 0 means --kill-child was not used */
        const char *procmnt = NULL;
        pid_t pid = 0;
        int fds[2];
@@ -379,8 +380,14 @@ int main(int argc, char *argv[])
                        propagation = parse_propagation(optarg);
                        break;
                case OPT_KILLCHILD:
-                       kill_child = 1;
                        forkit = 1;
+                       if (optarg) {
+                               if ((kill_child_signo = signame_to_signum(optarg)) < 0)
+                                       errx(EXIT_FAILURE, _("unknown signal: %s"),
+                                            optarg);
+                       } else {
+                               kill_child_signo = SIGKILL;
+                       }
                        break;
                default:
                        errtryhelp(EXIT_FAILURE);
@@ -439,8 +446,8 @@ int main(int argc, char *argv[])
                }
        }
 
-       if (kill_child)
-               if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
+       if (kill_child_signo != 0)
+               if (prctl(PR_SET_PDEATHSIG, kill_child_signo) < 0)
                        err(EXIT_FAILURE, "prctl failed");
 
        if (maproot) {