misc

Signed-off-by: Mattias Andrée <maandree@operamail.com>

3 files changed, 149 insertions, 14 deletions

diff --git a/src/config.h b/src/config.h
index e3a8bb0..261b96e 100644
--- a/src/config.h
+++ b/src/config.h
@@ -23,7 +23,7 @@
  * The root directory of all runtime data stored by MDS
  */
 #ifndef MDS_RUNTIME_ROOT_DIRECTORY
-#define MDS_RUNTIME_ROOT_DIRECTORY "/run/mds"
+#define MDS_RUNTIME_ROOT_DIRECTORY  "/run/mds"
 #endif
 
 
@@ -35,5 +35,47 @@
 #endif
 
 
+/**
+ * The group ID for the root group
+ */
+#ifndef ROOT_GROUP_GID
+#define ROOT_GROUP_GID  0
+#endif
+
+/* There two names above are redundant, but hat is to avoid errors. */
+
+
+/**
+ * The byte length of the authentication token
+ */
+#ifndef TOKEN_LENGTH
+#define TOKEN_LENGTH  1024
+#endif
+
+
+/**
+ * Random number generator to use for generating a token
+ */
+#ifndef TOKEN_RANDOM
+#define TOKEN_RANDOM  "/dev/urandom"
+#endif
+
+
+/**
+ * The maximum number of command line arguments to allow
+ */
+#ifndef ARGC_LIMIT
+#define ARGC_LIMIT  50
+#endif
+
+
+/**
+ * The maximum number of display allowed on the system
+ */
+#ifndef DISPLAY_MAX
+#define DISPLAY_MAX  1000
+#endif
+
+
 #endif
 
diff --git a/src/mds.c b/src/mds.c
index 07041fc..90d77ad 100644
--- a/src/mds.c
+++ b/src/mds.c
@@ -15,6 +15,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include "mds.h"
 #include "config.h"
 
 #include <sys/stat.h>
@@ -22,6 +23,8 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <errno.h>
+#include <limits.h>
+#include <fcntl.h>
 
 
 /**
@@ -33,12 +36,15 @@
  */
 int main(int argc, const char** argv)
 {
-  struct stat attr;
+  char pathname[PATH_MAX];
+  unsigned int display;
+  FILE *f;
+  int fd;
   
   (void) argv;
   
   /* Sanity check the number of command line arguments. */
-  if (argc > 50)
+  if (argc > ARGC_LIMIT)
     {
       fprintf(stderr,
 	      "%s: that number of arguments is ridiculous, I will not allow it.\n",
@@ -56,6 +62,58 @@ int main(int argc, const char** argv)
     }
   
   /* Create directory for socket files, PID files and such. */
+  if (create_runtime_root_directory())
+    return 1;
+  
+  /* Determine display index. */
+  for (display = 0; display < DISPLAY_MAX; display++)
+    {
+      snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/%u.pid",
+	       MDS_RUNTIME_ROOT_DIRECTORY, display);
+      
+      fd = open(pathname, O_CREAT | O_EXCL);
+      if (fd == -1)
+	{
+	  /* TODO reuse display index not no longer used */
+	  continue;
+	}
+      
+      close(fd);
+    }
+  if (display == DISPLAY_MAX)
+    {
+      fprintf(stderr,
+	      "%s: Sorry, too many displays on the system.\n",
+	      *argv);
+      return 1;
+      /* Yes, the directory could have been removed, but probably not. */
+    }
+  
+  /* TODO: Create PID file. */
+  
+  /* TODO: Save MDS_DISPLAY environment variable. */
+  
+  /* Drop privileges. They most not be propagated non-authorised components. */
+  /* setgid should not be set, but just to be safe we are restoring both user and group. */
+  if ((seteuid(getuid()) < 0) || (setegid(getgid()) < 0))
+    {
+      perror(*argv);
+      return 1;
+    }
+  
+  return 0;
+}
+
+
+/**
+ * Create directory for socket files, PID files and such
+ * 
+ * @return  Non-zero on error
+ */
+int create_runtime_root_directory(void)
+{
+  struct stat attr;
+  
   if (stat(MDS_RUNTIME_ROOT_DIRECTORY, &attr) == 0)
     {
       /* Cannot create the directory, its pathname refers to an existing. */
@@ -69,19 +127,23 @@ int main(int argc, const char** argv)
 	}
     }
   else
-    /* Directory is missing, create it. */
-    if (mkdir(MDS_RUNTIME_ROOT_DIRECTORY, 0755) < 0)
-      if (errno != EEXIST) /* Unlikely race condition. */
+    {
+      /* Directory is missing, create it. */
+      if (mkdir(MDS_RUNTIME_ROOT_DIRECTORY, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) < 0)
 	{
-	  perror(*argv);
-	  return 1;
+	  if (errno != EEXIST) /* Unlikely race condition. */
+	    {
+	      perror(*argv);
+	      return 1;
+	    }
 	}
-  
-  /* Drop privileges. They most not be propagated non-authorised components. */
-  if (seteuid(getuid()) < 0)
-    {
-      perror(*argv);
-      return 1;
+      else
+	/* Set ownership. */
+	if (chown(MDS_RUNTIME_ROOT_DIRECTORY, ROOT_USER_UID, ROOT_GROUP_GID) < 0)
+	  {
+	    perror(*argv);
+	    return 1;
+	  }
     }
   
   return 0;
diff --git a/src/mds.h b/src/mds.h
new file mode 100644
index 0000000..c03537d
--- /dev/null
+++ b/src/mds.h
@@ -0,0 +1,31 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef MDS_MDS_H
+#define MDS_MDS_H
+
+
+/**
+ * Create directory for socket files, PID files and such
+ * 
+ * @return  Non-zero on error
+ */
+int create_runtime_root_directory(void);
+
+
+#endif
+