python.lang.best-practice.open-never-closed.open-never-closed

profile photo of semgrepsemgrep
Author
6,393
Download Count*
LGPL Commons Clause
License

file object opened without corresponding close

Run Locally

Run in CI

Semgrep CI docs

Defintion

Edit RuleView Source
Open in Playground 
rules:
  - id: open-never-closed
    patterns:
      - pattern-not-inside: |
          $F = open(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = io.open(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = tarfile.open(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = ZipFile.open(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = tempfile.TemporaryFile(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = tempfile.NamedTemporaryFile(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = tempfile.SpooledTemporaryFile(...)
          ...
          $F.close()
      - pattern-not-inside: |
          $F = open(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = io.open(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = tarfile.open(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = ZipFile.open(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = tempfile.TemporaryFile(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = tempfile.NamedTemporaryFile(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-not-inside: |
          $F = tempfile.SpooledTemporaryFile(...)
          ...
          try:
              ...
          finally:
              $F.close()
      - pattern-either:
          - pattern: $F = open(...)
          - pattern: $F = io.open(...)
          - pattern: $F = tarfile.open(...)
          - pattern: $F = ZipFile.open(...)
          - pattern: $F = tempfile.TemporaryFile(...)
          - pattern: $F = tempfile.NamedTemporaryFile(...)
          - pattern: $F = tempfile.SpooledTemporaryFile(...)
    message: file object opened without corresponding close
    languages:
      - python
    severity: ERROR
    metadata:
      category: best-practice
      technology:
        - python
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]

Examples

open-never-closed.py

def func1():
    # ruleid:open-never-closed
    fd = open('foo')
    x = 123


def func2():
    # ok:open-never-closed
    fd = open('bar')
    fd.close()

def func3():
    # ok:open-never-closed
    fd = open('baz')
    try:
        pass
    finally:
        fd.close()