Bug#1065498: diffoscope: Crash on files without read permission

[rclobus at rclobus.nl]

Package: diffoscope
Version: 259
Severity: normal

Dear Maintainer,

I am able to crash diffoscope with a simple scenario:

sudo touch a b # Create 2 zero-byte files (owner=root)
sudo chmod go= a b # No access rights for group and others, default 
access for root
diffoscope a b # This is a regular user, who is not allowed to read 
these files

When the file does not have read permission for the current user, Python 
exists with

PermissionError: [Errno 13] Permission denied: 'a'

Expected behaviour:
* Skip this file and add it to the output as an inaccessible file 
(similar to how /dev/stdout is handled)

With kind regards,
Roland Clobus

-- System Information:
Debian Release: trixie/sid
   APT prefers unstable
   APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.6.13-amd64 (SMP w/4 CPU threads; PREEMPT)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages diffoscope depends on:
ii  diffoscope-minimal  259

Versions of packages diffoscope recommends:
ii  7zip                             23.01+dfsg-8
ii  aapt                             1:14~beta1-2+b1
ii  abootimg                         0.6-1.1
ii  acl                              2.3.2-1
ii  androguard                       3.4.0~a1-10
ii  apksigcopier                     1.1.1-1
ii  apksigner                        31.0.2-1
ii  apktool                          2.7.0+dfsg-7
ii  binutils-multiarch               2.42-3
ii  bzip2                            1.0.8-5+b2
ii  caca-utils                       0.99.beta20-4
ii  colord                           1.4.6-5
ii  coreboot-utils                   4.15~dfsg-4
ii  db-util                          5.3.3
ii  default-jdk-headless             2:1.17-75
ii  device-tree-compiler             1.7.0-2
ii  dexdump                          14.0.0+r15-1+b1
ii  docx2txt                         1.4-5
ii  e2fsprogs                        1.47.0-2.3
ii  enjarify                         1:1.0.3-5
ii  ffmpeg                           7:6.1.1-2
ii  fontforge-extras                 1:20230101~dfsg-1+b1
ii  fonttools                        4.46.0-1
ii  fp-utils                         3.2.2+dfsg-32
ii  fp-utils-3.2.2 [fp-utils]        3.2.2+dfsg-32
ii  genisoimage                      9:1.1.11-3.4
ii  gettext                          0.21-14+b1
ii  ghc                              9.4.7-3
ii  ghostscript                      10.02.1~dfsg-3
ii  giflib-tools                     5.2.2-1
ii  gnumeric                         1.12.56-2+b1
ii  gnupg-utils                      2.2.40-1.1+b1
ii  gpg                              2.2.40-1.1+b1
ii  hdf5-tools                       1.10.10+repack-3.1
ii  html2text                        2.2.3-2
ii  imagemagick                      8:6.9.12.98+dfsg1-5.1
ii  imagemagick-6.q16 [imagemagick]  8:6.9.12.98+dfsg1-5.1
ii  jsbeautifier                     1.14.11-1
ii  libarchive-tools                 3.7.2-1.1
ii  libxmlb-utils                    0.3.15-1
ii  llvm                             1:16.0-57
ii  lz4 [liblz4-tool]                1.9.4-1+b2
ii  lzip                             1.24.1-1
ii  mono-utils                       6.8.0.105+dfsg-3.5
ii  ocaml-nox                        4.14.1-1
ii  odt2txt                          0.5-7
ii  oggvideotools                    0.9.1-6
ii  openssh-client                   1:9.6p1-4
ii  openssl                          3.1.5-1.1
ii  pgpdump                          0.36-1
ii  poppler-utils                    22.12.0-2+b1
ii  procyon-decompiler               0.6.0-1
ii  python3-argcomplete              3.1.4-1
ii  python3-binwalk                  2.3.4+dfsg1-4
ii  python3-debian                   0.1.49
ii  python3-defusedxml               0.7.1-2
ii  python3-guestfs                  1:1.52.0-2.1
ii  python3-jsondiff                 2.0.0-2
ii  python3-pdfminer                 20221105+dfsg-1
ii  python3-progressbar              2.5-4
ii  python3-pypdf                    4.0.2-1
ii  python3-pyxattr                  0.8.1-1+b1
ii  python3-rpm                      4.18.2+dfsg-2.1
ii  python3-tlsh                     3.4.4+20151206-1.4+b5
ii  r-base-core                      4.3.3-1
ii  radare2                          5.5.0+dfsg-1.1
ii  rpm2cpio                         4.18.2+dfsg-2.1
ii  sng                              1.1.0-4
ii  sqlite3                          3.45.1-1
ii  squashfs-tools                   1:4.6.1-1
ii  tcpdump                          4.99.4-3
ii  u-boot-tools                     2024.01+dfsg-1
ii  unzip                            6.0-28
ii  wabt                             1.0.34+dsfg2+~cs1.0.32-1
ii  xmlbeans                         4.0.0-2
ii  xxd                              2:9.1.0016-1
ii  xz-utils                         5.6.0-0.2
ii  zip                              3.0-13
ii  zstd                             1.5.5+dfsg2-2

Versions of packages diffoscope suggests:
ii  libjs-jquery  3.6.1+dfsg+~3.5.14-1

-- no debconf information