https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92100
Bug ID: 92100
Summary: Formatted stream IO irreproducible read with binary
data in file
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libfortran
Assignee: unassigned at gcc dot gnu.org
Reporter: angus at agibson dot me
Target Milestone: ---
Created attachment 47036
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47036&action=edit
Reproducing example
I have a file with mixed ASCII/binary data (a GMSH 4.1 file). Reading an ASCII
line which is followed by binary data from this file with access="stream" and
form="formatted" works as expected. However, if I save the file position before
the read, and try to repeat the read by passing pos=saved_pos, the result
differs. e.g. for the code below, on the attached test problem:
first read: $MeshFormat
re-read:
When I would expect to read the same data both times. I can get around this by
inserting a rewind statement before the second read.
program stream_test
implicit none
character(len=20) :: buf
integer :: saved_pos
open(42, file='test.txt', action='read', access='stream', form='formatted')
inquire(42, pos=saved_pos)
read(42, *) buf
print *, 'first read: ', trim(buf)
! try to re-read from the same position
! rewind(42) ! behaves as expected
read(42, *, pos=saved_pos) buf
print *, 're-read: ', trim(buf)
end program
