[Bug target/65895] New: Segfault building cross GCC 5.1.0 for Target AVR on Mac OSX 10.10.3 (using Apple LLVM version 6.1.0 (clang-602.0.49))

["hdusel at macbay dot de" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65895

            Bug ID: 65895
           Summary: Segfault building cross GCC 5.1.0 for Target AVR on
                    Mac OSX 10.10.3 (using Apple LLVM version 6.1.0
                    (clang-602.0.49))
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hdusel at macbay dot de
  Target Milestone: ---
              Host: Mac OS X 10.10.3
            Target: AVR
             Build: Mac OS X 10.10.3

Using Apple LLVM version 6.1.0 (clang-602.0.49) to build released version 5.1.0
leads into a segfault:

-----------------------------------
g++ 
/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/config/avr/gen-avr-mmcu-specs.c
-o gen-avr-mmcu-specs -I. -I.
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/.
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/../include
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/../libcpp/include
-I/tmp/build_cross_gcc/gcc-5.1.0_build_avr/./gmp
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gmp
-I/tmp/build_cross_gcc/gcc-5.1.0_build_avr/./mpfr
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/mpfr
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/mpc/src 
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/../libdecnumber
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/../libdecnumber/dpd
-I../libdecnumber
-I/tmp/build_cross_gcc/gcc-5.1.0_arch/gcc-5.1.0/gcc/../libbacktrace 
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is
deprecated
rm -rf device-specs
mkdir device-specs && cd device-specs &&  ../gen-avr-mmcu-specs
/bin/sh: line 1: 62583 Segmentation fault: 11  ../gen-avr-mmcu-specs
make[2]: *** [s-device-specs] Error 139
make[1]: *** [all-gcc] Error 2
make: *** [all] Error 2
-----------------------------------

I finally found the reason for the segfault! It is located within
gcc/config/avr/gen-avr-mmcu-specs.c

In the function print_mcu(const avr_mcu_t *mcu) For every spec file that is
about to be generated by gen-avr-mmcu-specs a file handle is created but this
handle is __not__ closed when the function leaves. 

On OS X 10.10.3 (haven't tried other versions of Mac OS X) the total number of
opened files per process is apparently lower than the files processed by this
tool. Hence after this count of opened handles has exceeded the OS will return
NULL for any further attempt to open a new file.

-> So accessing a NULL Pointer for the file handler leads to the segfault.

The solution is simple: Simply call fclose(f) when the function leaves. In
addition it would be fine if a returning file handle of NULL will be checked
and acknowledged by the tool by an appropriate error message either. At least
the code should not attempt to proceed with a NULL for the file handle though.

I verified this proposed changes on my system -> build proceeds.