Automatically detect if pies is started from docker

* lib/envop.c: Include sys/types.h (for ssize_t).
* src/pies.c (is_docker,no_init_option,init_detect): New functions.
(main): Call init_detect.
* src/utmp.c: Additional cpp magic to determine WTMPX_FILE and UTMPX_FILE.
* NEWS: Document the changes.
* doc/pies.texi: Likewise.  Also, fix improper node name (inetd.conf).
* configure.ac: Version 1.4.91

2 files changed, 92 insertions, 24 deletions

diff --git a/src/pies.c b/src/pies.c
index a8529ac..2aa110f 100644
--- a/src/pies.c
+++ b/src/pies.c
@@ -2262,7 +2262,66 @@ set_state_file_names (const char *base)
   if (!qotdfile)
     qotdfile = mkfilename (statedir, base, ".qotd");
 }
+
+/* Return 1 if pies is run from docker and 0 otherwise. */
+static int
+is_docker (void)
+{
+  FILE *fp;
+  char *id = NULL;
+  int res;
+  
+  fp = fopen ("/proc/self/cgroup", "r");
+  if (!fp)
+    return 0;
+  res = fscanf (fp, "%*d:%*[^:]:/docker/%ms\n", &id) == 1;
+  fclose (fp);
+  free (id);
+  return res;
+}
+
+/*
+ * Check if `--no-init' option is present in argv/argc.  Return 1 if so,
+ * 0 otherwise.
+ */
+static int
+no_init_option (int argc, char **argv)
+{
+  int i;
+  for (i = 1; i < argc; i++)
+    {
+      if (strcmp (argv[i], "--no-init") == 0)
+	return 1;
+    }
+  return 0;
+}
 
+/*
+ * init_detect - detect if we're run as init process.
+ * 
+ * Pies runs as init process if (1) it has PID 1, (2) is not started as docker
+ * entrypoint, and (3) the `--no-init' command line option is not given.
+ *
+ * The function sets init_process to 1 if pies runs as init process and 0
+ * otherwise.
+ *
+ * No matter the result, if PID is 1 it installs an early SIGCHLD handler,
+ * to ensure that the configuration preprocessor (if such is started) will be
+ * cleaned up properly on exit.
+ */
+static void
+init_detect (int argc, char **argv)
+{
+  init_process = getpid () == 1;
+  if (init_process)
+    {
+      int s[] = { SIGCHLD };
+      setsigvhan (sigchld_early, s, 1);
+      if (no_init_option (argc, argv) || is_docker ())
+	init_process = 0;
+    }
+}
+
 size_t pies_master_argc;
 char **pies_master_argv;
 
@@ -2290,22 +2349,8 @@ main (int argc, char **argv)
 
   set_quoting_style (NULL, shell_quoting_style);
 
-  init_process = getpid () == 1;
-  if (init_process)
-    {
-      int s[] = { SIGCHLD };
-      setsigvhan (sigchld_early, s, 1);
-    }
+  init_detect (argc, argv);
   
-  for (i = 1; i < argc; i++)
-    {
-      if (strcmp (argv[i], "--no-init") == 0)
-	{
-	  init_process = 0;
-	  break;
-	}
-    }
-
   /* Set default logging */
   if (SYSVINIT_ACTIVE)
     {
diff --git a/src/utmp.c b/src/utmp.c
index 4a1e746..8045370 100644
--- a/src/utmp.c
+++ b/src/utmp.c
@@ -26,10 +26,6 @@ typedef struct utmpx UTMPX;
 #  define pies_updwtmpx updwtmpx
 # endif
 # define GETUTXID getutxid
-# undef UTMP_FILE
-# define UTMP_FILE UTMPX_FILE
-# undef WTMP_FILE
-# define WTMP_FILE WTMPX_FILE
 # if defined HAVE_STRUCT_UTMPX_UT_NAME
 #  define UT_NAME(u) ((u)->ut_name)
 # elif defined HAVE_STRUCT_UTMPX_UT_USER
@@ -52,6 +48,33 @@ typedef struct utmp UTMPX;
 # define endutxent endutent
 #endif
 
+#if !defined(UTMPX_FILE) || !defined(WTMPX_FILE)
+# if !defined(UTMP_FILE) || !defined(WTMP_FILE)
+#  ifndef  HAVE_UTMPX_H
+#   include <utmp.h>
+#  endif
+#  if !defined(UTMP_FILE)
+#   if !defined(_PATH_UTMP)
+#    error "None of UTMPX_FILE, UTMP_FILE or _PATH_UTMP defined"
+#   else
+#    define UTMP_FILE _PATH_UTMP
+#   endif
+#  endif
+#  if !defined(WTMP_FILE)
+#   if !defined(_PATH_WTMP)
+#    error "None of WTMPX_FILE, WTMP_FILE or _PATH_WTMP defined"
+#   else
+#    define WTMP_FILE _PATH_WTMP
+#   endif
+#  endif
+# endif
+# if !defined(UTMPX_FILE)
+#  define UTMPX_FILE UTMP_FILE
+# endif
+# if !defined(WTMPX_FILE)
+#  define WTMPX_FILE WTMP_FILE
+# endif
+#endif
 
 #ifndef pies_updwtmpx
 static void
@@ -111,8 +134,8 @@ write_wtmpx (int type, const char *user, const char *id, pid_t pid,
   UTMPX utmp;
   static int wtmpxreboot = 0;
 
-  debug (2, (_("cannot open %s for writing"), WTMP_FILE));
-  if (access (WTMP_FILE, W_OK))
+  debug (2, (_("cannot open %s for writing"), WTMPX_FILE));
+  if (access (WTMPX_FILE, W_OK))
     {
       if (type == BOOT_TIME)
 	wtmpxreboot++;
@@ -125,7 +148,7 @@ write_wtmpx (int type, const char *user, const char *id, pid_t pid,
       --wtmpxreboot;
     }
   fill_utmp (&utmp, type, user, id, pid, line);
-  pies_updwtmpx (WTMP_FILE, &utmp);
+  pies_updwtmpx (WTMPX_FILE, &utmp);
 }  
 
 void
@@ -135,9 +158,9 @@ write_utmpx (int type, const char *user, const char *id, pid_t pid,
   UTMPX utmp;
   static int utmpreboot = 0;
 
-  if (access (UTMP_FILE, W_OK))
+  if (access (UTMPX_FILE, W_OK))
     {
-      debug (1, (_("cannot open %s for writing"), UTMP_FILE));
+      debug (1, (_("cannot open %s for writing"), UTMPX_FILE));
       if (type == BOOT_TIME)
 	utmpreboot++;
       return;