nspawn: optionally run a stub init process as PID 1

This adds a new switch --as-pid2, which allows running commands as PID 2, while a stub init process is run as PID 1.
This is useful in order to run arbitrary commands in a container, as PID1's semantics are different from all other
processes regarding reaping of unknown children or signal handling.

1 files changed, 92 insertions, 1 deletions

diff --git a/src/nspawn/nspawn-settings.c b/src/nspawn/nspawn-settings.c
index 3c552e0734..12524d3b89 100644
--- a/src/nspawn/nspawn-settings.c
+++ b/src/nspawn/nspawn-settings.c
@@ -24,6 +24,7 @@
 #include "conf-parser.h"
 #include "nspawn-network.h"
 #include "nspawn-settings.h"
+#include "parse-util.h"
 #include "process-util.h"
 #include "strv.h"
 #include "util.h"
@@ -39,7 +40,7 @@ int settings_load(FILE *f, const char *path, Settings **ret) {
         if (!s)
                 return -ENOMEM;
 
-        s->boot = -1;
+        s->start_mode = _START_MODE_INVALID;
         s->personality = PERSONALITY_INVALID;
 
         s->read_only = -1;
@@ -303,3 +304,93 @@ int config_parse_veth_extra(
 
         return 0;
 }
+
+int config_parse_boot(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Settings *settings = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        r = parse_boolean(rvalue);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse Boot= parameter %s, ignoring: %m", rvalue);
+                return 0;
+        }
+
+        if (r > 0) {
+                if (settings->start_mode == START_PID2)
+                        goto conflict;
+
+                settings->start_mode = START_BOOT;
+        } else {
+                if (settings->start_mode == START_BOOT)
+                        goto conflict;
+
+                if (settings->start_mode < 0)
+                        settings->start_mode = START_PID1;
+        }
+
+        return 0;
+
+conflict:
+        log_syntax(unit, LOG_ERR, filename, line, r, "Conflicting Boot= or ProcessTwo= setting found. Ignoring.");
+        return 0;
+}
+
+int config_parse_pid2(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Settings *settings = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        r = parse_boolean(rvalue);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse ProcessTwo= parameter %s, ignoring: %m", rvalue);
+                return 0;
+        }
+
+        if (r > 0) {
+                if (settings->start_mode == START_BOOT)
+                        goto conflict;
+
+                settings->start_mode = START_PID2;
+        } else {
+                if (settings->start_mode == START_PID2)
+                        goto conflict;
+
+                if (settings->start_mode < 0)
+                        settings->start_mode = START_PID1;
+        }
+
+        return 0;
+
+conflict:
+        log_syntax(unit, LOG_ERR, filename, line, r, "Conflicting Boot= or ProcessTwo= setting found. Ignoring.");
+        return 0;
+}