diff -Burp sed-4.1.5-orig/lib/utils.c sed-4.1.5-follow/lib/utils.c

--- sed-4.1.5-orig/lib/utils.c	2005-06-21 16:09:40.000000000 +0200

+++ sed-4.1.5-follow/lib/utils.c	2006-12-07 19:08:02.000000000 +0100

@@ -35,6 +35,12 @@

 # include <stdlib.h>

 #endif /* HAVE_STDLIB_H */

+#include <sys/types.h>

+#include <sys/stat.h>

+#include <unistd.h>

+#include <sys/sendfile.h>

+#include <fcntl.h>

+

 #include "utils.h"

 const char *myname;

@@ -315,32 +321,99 @@ do_ck_fclose(fp)

 }

-/* Panic on failing rename */

-void

-ck_rename (from, to, unlink_if_fail)

-  const char *from, *to;

-  const char *unlink_if_fail;

+#include <libgen.h>

+

+/* Follow symlink and panic if something fails.  Returned value is

+   ultimate symlink target, stored in malloc'd buffer.*/

+const char*

+ck_follow_symlink(const char * fname)

 {

-  int rd = rename (from, to);

-  if (rd != -1)

-    return;

+  static struct stat statbuf;

+  int err;

+  char * dir;

+

+  static size_t bufsize = 1024;

+  char * buf = malloc (bufsize);

+  char * buf2 = alloca (bufsize);

+

+  if (strlen (fname) >= bufsize)

+    panic("ck_follow_symlink: file name too long");

+  strcpy (buf, fname);

-  if (unlink_if_fail)

+  while (1)

     {

-      int save_errno = errno;

-      errno = 0;

-      unlink (unlink_if_fail);

+      err = lstat (buf, &statbuf);

+

+      if (err != 0)

+	panic("ck_follow_symlink: couldn't lstat %s: %s", buf, strerror(errno));

-      /* Failure to remove the temporary file is more severe, so trigger it first.  */

-      if (errno != 0)

-        panic (_("cannot remove %s: %s"), unlink_if_fail, strerror (errno));

+      if ((statbuf.st_mode & S_IFLNK) == S_IFLNK)

+	{

+	  err = readlink (buf, buf2, bufsize);

+

+	  if (err < 0)

+	    panic("ck_follow_symlink: readlink failed on %s: %s", buf, strerror(errno));

+	  else if (err == bufsize)

+	    panic("ck_follow_symlink: pointee name too long");

+	  else

+	    buf2 [err] = '\0';

+

+	  /* need to handle relative paths with care */

+	  dir = dirname (buf);    // dir part of orig path

+	  int len = strlen (dir); // orig path len

+	  if (buf2[0] != '/' && len != 1 && dir[0] != '.')

+	    {

+	      buf[len] = '/';

+	      strncpy (buf+len+1, buf2, bufsize - len - 1);

+	      if (buf[bufsize-1] != 0)

+		panic("ck_follow_symlink: pointee name too long");

+	    }

+	  else

+	    {

+	      strcpy (buf, buf2);

+	    }

+	}

+      else

+	break;

+    }

+

+  return buf;

+}

+/* Panic on failing unlink */

+void

+ck_unlink (name)

+  const char *name;

+{

+  if (unlink (name) == -1)

+    panic (_("cannot remove %s: %s"), name, strerror (errno));

+}

+

+/* Attempt to unlink denoted file if operation rd failed. */

+static int

+_unlink_if_fail (rd, unlink_if_fail)

+  int rd;

+  const char *unlink_if_fail;

+{

+  if (rd == -1 && unlink_if_fail)

+    {

+      int save_errno = errno;

+      ck_unlink (unlink_if_fail);

       errno = save_errno;

     }

-  panic (_("cannot rename %s: %s"), from, strerror (errno));

+  return rd != -1;

 }

+/* Panic on failing rename */

+void

+ck_rename (from, to, unlink_if_fail)

+  const char *from, *to;

+  const char *unlink_if_fail;

+{

+  if (!_unlink_if_fail (rename (from, to), unlink_if_fail))

+  panic (_("cannot rename %s: %s"), from, strerror (errno));

+}

diff -Burp sed-4.1.5-orig/lib/utils.h sed-4.1.5-follow/lib/utils.h

--- sed-4.1.5-orig/lib/utils.h	2005-06-21 16:09:40.000000000 +0200

+++ sed-4.1.5-follow/lib/utils.h	2006-12-07 19:00:11.000000000 +0100

@@ -29,6 +29,7 @@ void ck_fflush P_((FILE *stream));

 void ck_fclose P_((FILE *stream));

 size_t ck_getline P_((char **text, size_t *buflen, FILE *stream));

 FILE * ck_mkstemp P_((char **p_filename, char *tmpdir, char *base));

+const char* ck_follow_symlink P_((const char * fname));

 void ck_rename P_((const char *from, const char *to, const char *unlink_if_fail));

 VOID *ck_malloc P_((size_t size));

--- sed-4.1.5-orig/sed/execute.c	2006-12-08 16:33:20.000000000 +0100

+++ sed-4.1.5-follow/sed/execute.c	2006-12-07 18:53:11.000000000 +0100

@@ -712,16 +712,18 @@

   if (in_place_extension && output_file.fp != NULL)

     {

+      char * target_name = ck_strdup (ck_follow_symlink (input->in_file_name));

       ck_fclose (output_file.fp);

       if (strcmp(in_place_extension, "*") != 0)

         {

+          char *backup_file_name = get_backup_file_name(target_name);

+	  ck_rename (target_name, backup_file_name, input->out_file_name);

-          char *backup_file_name = get_backup_file_name(input->in_file_name);

-	  ck_rename (input->in_file_name, backup_file_name, input->out_file_name);

           free (backup_file_name);

 	}

+      ck_rename (input->out_file_name, target_name, input->out_file_name);

-      ck_rename (input->out_file_name, input->in_file_name, input->out_file_name);

       free (input->out_file_name);

+      free (target_name);

     }

   input->fp = NULL;