Space after multi-line backslash in Quadlet causes infinite loop in generator

[PJB3005]

Issue Description

The following quadlet definition causes podman-system-generator to get stuck in an infinite loop:

[Unit]
Description=OOF

[Container]
Image=ubuntu
Exec=/bin/echo \ 
    a

It's really important there is a space after the backslash. Otherwise it doesn't happen.

Steps to reproduce the issue

Steps to reproduce the issue

1. Put the above definition in /etc/containers/systemd/foo.container (make sure the space after the backslash persists)
2. /usr/lib/systemd/system-generators/podman-system-generator -v -dryrun
3. Log gets stuck on quadlet-generator[94834]: Loading source unit file /etc/containers/systemd/foo.container

Describe the results you received

Generator gets stuck, takes 100% of a CPU core, systemctl daemon-reload gets stuck.

Describe the results you expected

Either it works or it gives an explicit error (is it invalid syntax to have a space after the backslash?)

podman info output

host:
  arch: amd64
  buildahVersion: 1.31.3
  cgroupControllers:
  - cpuset
  - cpu
  - io
  - memory
  - hugetlb
  - pids
  - rdma
  - misc
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: conmon-2.1.8-1.el9.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.8, commit: 879ca989e09d731947cd8d9cbb41038549bf669d'
  cpuUtilization:
    idlePercent: 99.65
    systemPercent: 0.13
    userPercent: 0.22
  cpus: 12
  databaseBackend: boltdb
  distribution:
    distribution: '"almalinux"'
    version: "9.3"
  eventLogger: journald
  freeLocks: 2037
  hostname: moon
  idMappings:
    gidmap: null
    uidmap: null
  kernel: 5.14.0-362.8.1.el9_3.x86_64
  linkmode: dynamic
  logDriver: journald
  memFree: 44562337792
  memTotal: 66784952320
  networkBackend: netavark
  networkBackendInfo:
    backend: netavark
    dns:
      package: aardvark-dns-1.7.0-1.el9.x86_64
      path: /usr/libexec/podman/aardvark-dns
      version: aardvark-dns 1.7.0
    package: netavark-1.7.0-2.el9_3.x86_64
    path: /usr/libexec/podman/netavark
    version: netavark 1.7.0
  ociRuntime:
    name: crun
    package: crun-1.8.7-1.el9.x86_64
    path: /usr/bin/crun
    version: |-
      crun version 1.8.7
      commit: 53a9996ce82d1ee818349bdcc64797a1fa0433c4
      rundir: /run/user/0/crun
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  pasta:
    executable: ""
    package: ""
    version: ""
  remoteSocket:
    path: /run/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: false
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: true
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.2.1-1.el9.x86_64
    version: |-
      slirp4netns version 1.2.1
      commit: 09e31e92fa3d2a1d3ca261adaeb012c8d75a8194
      libslirp: 4.4.0
      SLIRP_CONFIG_VERSION_MAX: 3
      libseccomp: 2.5.2
  swapFree: 34314645504
  swapTotal: 34325131264
  uptime: 261h 43m 19.00s (Approximately 10.88 days)
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries:
  search:
  - registry.access.redhat.com
  - registry.redhat.io
  - docker.io
store:
  configFile: /etc/containers/storage.conf
  containerStore:
    number: 9
    paused: 0
    running: 7
    stopped: 2
  graphDriverName: overlay
  graphOptions:
    overlay.mountopt: nodev,metacopy=on
  graphRoot: /var/lib/containers/storage
  graphRootAllocated: 476306640896
  graphRootUsed: 14727639040
  graphStatus:
    Backing Filesystem: xfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "true"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 14
  runRoot: /run/containers/storage
  transientStore: false
  volumePath: /var/lib/containers/storage/volumes
version:
  APIVersion: 4.6.1
  Built: 1702419194
  BuiltTime: Tue Dec 12 23:13:14 2023
  GitCommit: ""
  GoVersion: go1.20.10
  Os: linux
  OsArch: linux/amd64
  Version: 4.6.1

Podman in a container

No

Privileged Or Rootless

Privileged

Upstream Latest Release

No

Additional environment details

Bare metal AlmaLinux 9.3 install

Additional information

No response

[ygalblum]

@PJB3005 thanks for reporting this issue. I've created a PR to fix it.