File exists but program can't open it

Question

G'day all.
I am trying to port some fortran programs from a True64 environment into Sun v9/SunStudio 11. On the alpha it has no problems, but on the Sun it can't open a file with a name that is only 78 characters long. The Fortran User's guide states that the maximum length for a file name is 1024 characters.. The file most certainly exists and is readable to the user: stat gives:
silo@eclipse /silo1/tech1/install/bin -> stat /silo1/tech1/install/import/rtmet/NCC/dayClim/200706/2007062720070627.dc
  File: `/silo1/tech1/install/import/rtmet/NCC/dayClim/200706/2007062720070627.dc'
  Size: 133170         Blocks: 288        IO Block: 8192   regular file
Device: 1d8005ah/30933082d     Inode: 110852      Links: 1
Access: (0664/-rw-rw-r--)  Uid: ( 3953/sielewiczj)   Gid: (  700/    ciss)
Access: 2008-07-23 12:44:00.533357000 +1000
Modify: 2008-07-04 14:21:00.107423000 +1000
Change: 2008-07-08 09:27:39.322719000 +1000The compiled Fortran code (called from a wrapper script) however:
[07/23/08 12:46]: silo_dc_import_wrapper starting
Determining dates to process
Now starting to process Silo 1998
aah, how sweet - found file /tmp/silo/DC_filelist                              
About to check  /silo1/tech1/install/import/rtmet/NCC/dayClim/200706/2007062720070627.dc                                              
In file not Found  /silo1/tech1/install/import/rtmet/NCC/dayClim/200706/2007062720070627.dc                                                Bye
******  FORTRAN RUN-TIME SYSTEM  ******
Error 2:  No such file or directory
Location:  the OPEN statement at line 770 of "dc_importer.f90"
Unit:  12
File:   /silo1/tech1/install/import/rtmet/NCC/dayClim/200706/2007062720070627.dc
AbortNote that it could succesfully open the file /tmp/silo/DC_filelist... The code in question is:
! Problematic snippet from much longer program..
         integer*4 eof, ymd
         character*120 in_file, filelist
         logical file_exists
         file_exists = .TRUE.
         filelist = params(2)
         inquire(file = filelist,  exist = file_exists)
         if ( file_exists == .FALSE. ) then
           write(*,'(3a)') 'Not Found ', filelist, ' Bye'
           return
         endif
         print *, "aah, how sweet - found file ", filelist
         open ( unit=11, file=filelist, status='OLD' ) ! THIS succeeds (/tmp/silo/... short filename)
         read ( 11, "(i8, A120)", iostat = eof) ymd, in_file
         do while ( eof == 0 )
            write (*,'(2a)') "About to check " , in_file
           inquire(file = in_file,  exist = file_exists)
           if ( file_exists == .FALSE. ) then
             write( *, '(3a)') 'In file not Found ', in_file, ' Bye'
!             return (commented out to see if open also gives an error..)
           endif
         open ( unit=12, file=in_file(1:len_trim(in_file)) , status='OLD' ) ! THIS is where the program bombs out.
         end doI am stumped. Why would this bomb out? The file exists, is readable, the filename is << 1024 characters.. I've also tried to run this as the user who owns the file, to no avail. Any suggestions, please?
Cheers,
Tony

Answer 1

First, check to be sure the program has read and execute access on every directory in the path to the file.
If the directory permissions are all OK, run your program under truss:
truss -f -a -vall -o /output/file/name/here your.progam.hereThere should be something like a stat() and an open() call for that file shown as failing in your truss output file. Hopefully that will give you some more information.