safer creation of temp files used in replication of LOAD DATA INFILE.

When we come to create these, they may already exist and it's necessary to delete these old, useless copies.

BitKeeper/etc/logging_ok

@@ -29,6 +29,7 @@ dellis@goetia.(none)
 dlenev@brandersnatch.localdomain
 dlenev@build.mysql.com
 dlenev@mysql.com
+gbichot@quadxeon.mysql.com
 gerberb@ou800.zenez.com
 gluh@gluh.(none)
 gluh@gluh.mysql.r18.ru

sql/log_event.cc

@@ -2360,7 +2360,9 @@ int Create_file_log_event::exec_event(struct st_relay_log_info* rli)
   strmov(p, ".info");			// strmov takes less code than memcpy
   strnmov(proc_info, "Making temp file ", 17); // no end 0
   thd->proc_info= proc_info;
-  if ((fd = my_open(fname_buf, O_WRONLY|O_CREAT|O_BINARY|O_TRUNC,
+  my_delete(fname_buf, MYF(0)); // old copy may exist already
+  if ((fd= my_create(fname_buf, CREATE_MODE,
+		     O_WRONLY | O_BINARY | O_EXCL | O_NOFOLLOW,
 		     MYF(MY_WME))) < 0 ||
       init_io_cache(&file, fd, IO_SIZE, WRITE_CACHE, (my_off_t)0, 0,
 		    MYF(MY_WME|MY_NABP)))
@@ -2383,7 +2385,9 @@ int Create_file_log_event::exec_event(struct st_relay_log_info* rli)
   my_close(fd, MYF(0));
   
   // fname_buf now already has .data, not .info, because we did our trick
-  if ((fd = my_open(fname_buf, O_WRONLY|O_CREAT|O_BINARY|O_TRUNC,
+  my_delete(fname_buf, MYF(0)); // old copy may exist already
+  if ((fd= my_create(fname_buf, CREATE_MODE,
+		     O_WRONLY | O_BINARY | O_EXCL | O_NOFOLLOW,
 		     MYF(MY_WME))) < 0)
   {
     slave_print_error(rli,my_errno, "Error in Create_file event: could not open file '%s'", fname_buf);
@@ -2426,7 +2430,7 @@ int Append_block_log_event::exec_event(struct st_relay_log_info* rli)
   memcpy(p, ".data", 6);
   strnmov(proc_info, "Making temp file ", 17); // no end 0
   thd->proc_info= proc_info;
-  if ((fd = my_open(fname, O_WRONLY|O_APPEND|O_BINARY, MYF(MY_WME))) < 0)
+  if ((fd = my_open(fname, O_WRONLY|O_APPEND|O_BINARY|O_NOFOLLOW, MYF(MY_WME))) < 0)
   {
     slave_print_error(rli,my_errno, "Error in Append_block event: could not open file '%s'", fname);
     goto err;
@@ -2455,7 +2459,7 @@ int Execute_load_log_event::exec_event(struct st_relay_log_info* rli)
   Load_log_event* lev = 0;
 
   memcpy(p, ".info", 6);
-  if ((fd = my_open(fname, O_RDONLY|O_BINARY, MYF(MY_WME))) < 0 ||
+  if ((fd = my_open(fname, O_RDONLY|O_BINARY|O_NOFOLLOW, MYF(MY_WME))) < 0 ||
       init_io_cache(&file, fd, IO_SIZE, READ_CACHE, (my_off_t)0, 0,
 		    MYF(MY_WME|MY_NABP)))
   {