Add a -f (`force') option to cvt-wtmp. This might help people with

slightly bogus wtmp files (it definately helps in Jordan's case).

Also add a README explaining what all this is for.

3 files changed, 94 insertions, 15 deletions

diff --git a/tools/3.0-upgrade/Makefile b/tools/3.0-upgrade/Makefile
index 68ab9f1..fedda74 100644
--- a/tools/3.0-upgrade/Makefile
+++ b/tools/3.0-upgrade/Makefile
@@ -1,5 +1,8 @@
 all: cvt-wtmp
 
+CLEANFILES += cvt-wtmp
+
 cvt-wtmp: cvt-wtmp.c /usr/include/utmp.h
 
+
 .include <bsd.prog.mk>
diff --git a/tools/3.0-upgrade/README b/tools/3.0-upgrade/README
new file mode 100644
index 0000000..0d14d7b
--- /dev/null
+++ b/tools/3.0-upgrade/README
@@ -0,0 +1,29 @@
+By 1996/12/04, the utmp element size has been changed, in order to
+allow for longer usernames.  This change renders all existing wtmp
+files unusable.  The cvt-wtmp utility is provided as an aid to convert
+your old wtmp files into the new format, so you don't lose the
+existing track record.
+
+The tool cannot handle gzip'ed wtmp backups, so unzip them first if
+you need.  Then simply call it as:
+
+	./cvt-tmp /var/log/wtmp*
+
+The old wtmp files are being renamed to <file>.bak, so nothing will be
+lost even in case of a failure.  If you are only about to test whether
+the tool will grok your files correctly, you can run it as:
+
+	./cvs-tmp -n /var/log/wtmp*
+
+The tool tries an ``educated guess'', based on the reasonability of
+the timestamp values in the wtmp file.  If it fails to recognize the
+format of your wtmp, it normally bails out, or at least ignores
+garbage records.  In this case, rename the .bak files to the original
+name, and try to force the conversion:
+
+	./cvs-tmp -f /var/log/wtmp.xxx
+
+Make sure to verify the result however!
+
+
+Dresden, Jan 2, 1996			Joerg  <joerg@freebsd.org>
diff --git a/tools/3.0-upgrade/cvt-wtmp.c b/tools/3.0-upgrade/cvt-wtmp.c
index 9d034b1..3f18d15 100644
--- a/tools/3.0-upgrade/cvt-wtmp.c
+++ b/tools/3.0-upgrade/cvt-wtmp.c
@@ -23,7 +23,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $Id$
+ * $Id: cvt-wtmp.c,v 1.1 1996/12/16 16:12:35 joerg Exp $
  *
  */
 
@@ -63,7 +63,7 @@ struct outmp {
 };
 
 void	usage(void);
-void	convert(const char *, int);
+void	convert(const char *, int, int);
 
 /*
  * NB: We cannot convert lastlog yet, but we don't need either.
@@ -72,19 +72,23 @@ void	convert(const char *, int);
 void
 usage(void)
 {
-  errx(EX_USAGE, "usage: cvt-wtmp [-n] /var/log/wtmp*");
+  errx(EX_USAGE, "usage: cvt-wtmp [-f] [-n] /var/log/wtmp*");
 }
 
 
 int
 main(int argc, char **argv)
 {
-  int errs, i, nflag, rv;
+  int errs, i, nflag, forceflag, rv;
 
-  errs = nflag = 0;
-  while ((i = getopt(argc, argv, "n")) != EOF)
+  errs = nflag = forceflag = 0;
+  while ((i = getopt(argc, argv, "fn")) != EOF)
     switch (i)
       {
+      case 'f':
+	forceflag++;
+	break;
+
       case 'n':
 	nflag++;
 	break;
@@ -99,25 +103,26 @@ main(int argc, char **argv)
     usage();
 
   for (;argc > 0; argc--, argv++)
-    convert(*argv, nflag);
+    convert(*argv, nflag, forceflag);
 
   return 0;
 }
 
 void
-convert(const char *name, int nflag)
+convert(const char *name, int nflag, int forceflag)
 {
   struct stat sb;
   struct timeval tv[2];
   char xname[1024], yname[1024];
   unsigned char buf[128];	/* large enough to hold one wtmp record */
   int fd1, fd2;
-  size_t off;
+  size_t off, shouldbe;
   int old, new;
   time_t now, early, *t;
   struct tm tm;
   struct utmp u;
   struct outmp *ou;
+  enum { OLD, NEW } which = OLD; /* what we're defaulting to */
 
   if (stat(name, &sb) == -1)
     {
@@ -166,9 +171,30 @@ convert(const char *name, int nflag)
 	  /* unreasonable, collect another entry */
 	  if (off > sizeof buf)
 	    {
-	      (void) unlink(xname);
-	      errx(EX_UNAVAILABLE, "I can't seem to make sense out of file \"%s\"",
-		   name);
+	      if (!forceflag)
+		{
+	      	  (void) unlink(xname);
+		  errx(EX_UNAVAILABLE, "I can't seem to make sense out of file \"%s\",\n"
+		       "Could have forced using -f.",
+		     name);
+		}
+	      else
+		{
+		  warnx("Record # %d in file \"%s\" seems bogus\n"
+			"(time: %d, previous time: %d, now: %d),\n"
+			"continuing anyway.",
+			old + new + 1, name, *t, early, now);
+		  if (which == NEW)
+		    {
+		      (void)lseek(fd2, sizeof(struct utmp) - sizeof buf, SEEK_CUR);
+		      goto write_new;
+		    }
+		  else
+		    {
+		      (void)lseek(fd2, sizeof(struct outmp) - sizeof buf, SEEK_CUR);
+		      goto write_old;
+		    }
+		}
 	    }
 	  continue;
 	}
@@ -176,6 +202,8 @@ convert(const char *name, int nflag)
       if (off == sizeof(struct utmp))
 	{
 	  /* new wtmp record */
+	  which = NEW;
+	write_new:
 	  new++;
 	  if (!nflag)
 	    {
@@ -186,6 +214,8 @@ convert(const char *name, int nflag)
       else if (off == sizeof(struct outmp))
 	{
 	  /* old fart */
+	  which = OLD;
+	write_old:
 	  old++;
 	  if (!nflag)
 	    {
@@ -201,9 +231,26 @@ convert(const char *name, int nflag)
 	}
       else
 	{
-	  warnx("Illegal record in file \"%s\", ignoring.", name);
-	  off = 0;
-	  continue;
+	  if (!forceflag)
+	    {
+	      warnx("Illegal record in file \"%s\", ignoring.", name);
+	      off = 0;
+	      continue;
+	    }
+	  else
+	    {
+	      warnx("Illegal record in file \"%s\", considering it %s one.",
+		    name, (which == OLD? "an old": "a new"));
+	      shouldbe = (which == OLD? sizeof(struct outmp): sizeof(struct utmp));
+	      if (off < shouldbe)
+		(void)read(fd2, &buf[off], shouldbe - off);
+	      else
+		(void)lseek(fd2, shouldbe - off, SEEK_CUR);
+	      if (which == OLD)
+		goto write_old;
+	      else
+		goto write_new;
+	    }
 	}
       off = 0;
       /*