http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54736
Bug #: 54736
Summary: GFORTRAN_CONVERT_UNIT causes malloc error on several
platforms
Classification: Unclassified
Product: gcc
Version: 4.7.1
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: libfortran
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: sha...@utk.edu
I have a code that has multiple large data files that are written in big
endian format. To deal with this on many platforms, a script was written
that, among various other things, sets a few units to read as big endian
by using GFORTRAN_CONVERT_UNIT='native;big_endian:60-70,80-89'. However,
when the Fortran program is called from the script I get:
scale: malloc.c:2368: sysmalloc: Assertion `(old_top == (((mbinptr)
(((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct
malloc_chunk, fd)))) && old_size == 0) ||
((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof
(struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2
* (sizeof(size_t))) - 1))) && ((old_to
p)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.
This reliably happens on any Linux platform I've tested it on *except*
Fedora/RHEL.
I've been able to reliably reproduce the problem on several 32-bit
machines (Arch Linux (GCC 4.7.1), OpenSUSE 12.2, Ubuntu 12.10 Beta 1) by
creating and running these two programs:
Write program:
[shane@shane-laptop ~/temp/testgfortran]$ cat test_write.f90
program test_write
implicit none
integer, parameter :: NUM = 10
integer :: i
open(unit=88,form='unformatted',convert='big_endian')
do i = 1,NUM
write (88) i
end do
close(88)
end program test_write
Read Program:
[shane@shane-laptop ~/temp/testgfortran]$ cat test_read.f90
program test_write
implicit none
integer, parameter :: NUM = 10
integer :: readInt
integer :: i
open(unit=88,form='unformatted')
do i = 1,NUM
read (88) readInt
write (*,*) readInt
end do
close(88)
end program test_write
And testing:
[shane@shane-laptop ~/temp/testgfortran]$ ./test_write
[shane@shane-laptop ~/temp/testgfortran]$ ./test_read
16777216
At line 10 of file test_read.f90 (unit = 88, file = 'fort.88')
Fortran runtime error: End of file
[shane@shane-laptop ~/temp/testgfortran]$
GFORTRAN_CONVERT_UNIT='native;big_endian:88' ./test_read
test_read: malloc.c:2368: sysmalloc: Assertion `(old_top == (((mbinptr)
(((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct
malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >=
(unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))
+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) &&
((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)'
failed.
Aborted
[shane@shane-laptop ~/temp/testgfortran]$
GFORTRAN_CONVERT_UNIT='big_endian' ./test_read
1
2
3
4
5
6
7
8
9
10
Obviously the first invocation of test_read fails because the endianess
is wrong, but the second one should work. Running gdb yields:
Program received signal SIGABRT, Aborted.
0xb7fdd424 in __kernel_vsyscall ()
However, the above test program does work on all of the 64-bit machines
I've tested.
I found that by commenting out the lines 582-583 in libgfortran/runtime/
environ.c I can get it to work.
I don't really know why it's accessing an element in the elist structure
that hasn't been allocated yet. This loop doesn't seem to do anything to
me. Since I don't know the reprocussions of just commenting out stuff
willy nilly I'll leave the implementation details to someone with more
knowledge, but this seems like a good place to start.
