[Bug c/66909] New: Internal Compiler Error when #including files from /sys on Linux

[Bug c/66909] New: Internal Compiler Error when #including files from /sys on Linux

[nate at natecraun dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66909

            Bug ID: 66909
           Summary: Internal Compiler Error when #including files from
                    /sys on Linux
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nate at natecraun dot net
  Target Milestone: ---

Hello,

I have encountered a bug where #including files from /sys causes gcc to have an
internal compiler error:

    In file included from bug.c:1:0:

    bug.c:1:0: internal compiler error: Aborted
     #include "/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size"
     ^
    Please submit a full bug report,
    with preprocessed source if appropriate.
    See <http://bugzilla.redhat.com/bugzilla> for instructions.


Ths seems to cause an abort on gcc 5.1.1 and a segfault on gcc 4.8. Clang
manages to #include the file, but produces about 4000 some warnings about null
characters, so this might be a hint about what's going wrong.

Now of course I don't think there is any practical reason to #include files
from /sys. But it still shouldn't cause a compiler crash.

The bug can be reproduced with a source file #including any file from /sys

For example:

bug.c:

    #include "/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size"


Here is the .i file.

bug.i:

    # 1 "bug.c"
    # 1 "<built-in>"
    # 1 "<command-line>"
    # 1 "/usr/include/stdc-predef.h" 1 3 4
    # 1 "<command-line>" 2
    # 1 "bug.c"

Here is gcc -v:

Using built-in specs.
COLLECT_GCC=/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/5.1.1/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array
--disable-libgcj --with-default-libstdcxx-abi=c++98 --with-isl --enable-libmpx
--enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 5.1.1 20150618 (Red Hat 5.1.1-4) (GCC) 


My uname -a:

Linux localhost.localdomain 4.0.6-300.fc22.x86_64 #1 SMP Tue Jun 23 13:58:53
UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

[Bug c/66909] Internal Compiler Error when #including files from /sys on Linux

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66909

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-07-17
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.

[Bug preprocessor/66909] Internal Compiler Error when #including files from /sys on Linux

[nate at natecraun dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66909

--- Comment #2 from Nate Craun <nate at natecraun dot net> ---
It seems that clang has a similar issue. I added an entry on their bug tracker
here: https://llvm.org/bugs/show_bug.cgi?id=24168

As mentioned in clang's bug tracker:

I think the problem is related to the use of stat. For example, the manpage for
stat() mentions:

"For  most files under the /proc directory, stat() does not return the file
size in the st_size field; instead the field is returned with the value 0."

To test this out I wrote another test that tries to #include a file from /proc.

#include "/proc/meminfo"

However this did not #include the text from the /proc/meminfo at all. Running
the preprocessor on this produced an empty file. This is presumably because
stat() is saying /proc/meminfo has zero bytes.

I don't know if this #including files from proc bug should have its own issue
or not, as it seems to be related to the same underlying issue of stat()
behaving differently on procfs, sysfs, and maybe others.

Like I said before though, I don't have any practical use for #including files
from /proc or /sys. But the preprocessor should still be able to do this
textual inclusion correctly.

I haven't tried this out yet, but now I'm wondering if #include will have
issues on other special files on Linux: pipes, sockets, dev files, etc.

[Bug preprocessor/66909] Internal Compiler Error when #including files from /sys on Linux

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66909

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is 4.7 backtrace:
t65.c:1:0: internal compiler error: Segmentation fault
0x7547af crash_signal
        /bajas/pinskia/src/toolchain-47/scripts/../src/gcc/toplev.c:348
0xa55004 linemap_macro_map_lookup
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/line-map.c:583
0xa55004 linemap_lookup
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/line-map.c:514
0xa551ca linemap_macro_loc_to_spelling_point
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/line-map.c:919
0xa551ca linemap_resolve_location
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/line-map.c:1069
0xa5524b linemap_location_in_system_header_p
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/line-map.c:758
0xa4066e diagnostic_report_diagnostic
        /bajas/pinskia/src/toolchain-47/scripts/../src/gcc/diagnostic.c:524
0x4dd784 c_cpp_error
       
/bajas/pinskia/src/toolchain-47/scripts/../src/gcc/c-family/c-common.c:8944
0xa4a3fd cpp_diagnostic
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/errors.c:64
0xa4a556 cpp_error
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/errors.c:79
0xa4ec4f read_file_guts
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/files.c:645
0xa4ec4f read_file
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/files.c:678
0xa4f6bd should_stack_file
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/files.c:723
0xa4f6bd _cpp_stack_file
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/files.c:801
0xa47b35 do_include_common
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/directives.c:792
0xa487e0 _cpp_handle_directive
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/directives.c:491
0xa5443c _cpp_lex_token
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/lex.c:1952
0xa583c7 cpp_get_token_1
        /bajas/pinskia/src/toolchain-47/scripts/../src/libcpp/macro.c:2245
0x4e8044 c_lex_with_flags
        /bajas/pinskia/src/toolchain-47/scripts/../src/gcc/c-family/c-lex.c:302
0x4a651f c_lex_one_token
        /bajas/pinskia/src/toolchain-47/scripts/../src/gcc/c-parser.c:219

[Bug preprocessor/66909] Internal Compiler Error when #including files from /sys on Linux

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66909

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
         Resolution|---                         |FIXED
   Target Milestone|---                         |7.0
             Status|NEW                         |RESOLVED

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the problem is when it is warning:
  if (regular && total != size && STAT_SIZE_RELIABLE (file->st))
    cpp_error (pfile, CPP_DL_WARNING,
               "%s is shorter than expected", file->path);


So I think it was fixed by r7-1651.