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0015743

CMake

public

2015-09-15 11:15

2016-06-10 14:31

Reporter

Andreas Schuh

Assigned To

Kitware Robot

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

moved

Platform

x86_64

Ubuntu

OS Version

14.04

Product Version

CMake 3.3.1

Target Version

Fixed in Version

Summary

0015743: get_filename_component turns real path to ABSOLUTE path

Description

I encountered a very strange behaviour of the get_filename_component using the ABSOLUTE subcommand. The given input path was before turned into a real path with symbolic links resolved using the REALPATH subcommand. Calling get_filename_component with ABSOLUTE on this real path I would have expected an unchanged path. Instead, ABSOLUTE returns a path with symbolic links again! Note that both the source and build directory are located in different symlinked directory paths.

Looking at the C++ code of the get_filename_component command revealed some strange call to SystemTools::CheckTranslationPath in SystemTools::CollapseFullPath which implements the ABSOLUTE subcommand. There is also a commented line beforehand with a comment expecting to break something by doing so... the call to SystemTools::AddTranslationPath.

The issue affects also previous releases (tried 3.2.2 and 2.8.12.2).

IMHO I find it extremely strange that get_filename_component needs such translation table (without having digged deeper to fully understand its purpose). Cleaning a path or splitting it into parts should be a purely string based operation without actual file system information.

Steps To Reproduce

1. Create directory hierarchy with symlinks similar to my scenario:

  Real source directory:
    /vol/medic01/users/as12312/Code/CMakeGetFileNameComponentIssue

  Real build directory:
    /vol/biomedic/users/as12312/build/merapi/cmake-get_filename_component-issue

  Symbolic links:
    /homes/as12312/Code -> /vol/medic01/users/as12312/Code
    /homes/as12312/opt -> /vol/biomedic/users/as12312

2. Copy attached CMakeLists.txt to the source directory
3. Change into the symlinked build directory and use the symbolic link to the source directory as argument to CMake

  cd /homes/as12312/opt/build/merapi/cmake-get_filename_component-issue
  cmake /homes/as12321/Code/CMakeGetFileNameComponentIssue

The output is the following:

CMAKE_SOURCE_DIR:
    REALPATH = /vol/medic01/users/as12312/Code/CMakeGetFileNameComponentIssue
    ABSOLUTE = /vol/medic01/users/as12312/Code/CMakeGetFileNameComponentIssue
CMAKE_BINARY_DIR:
    REALPATH = /vol/biomedic/users/as12312/build/merapi/cmake-get_filename_component-issue
    ABSOLUTE = /homes/as12312/opt/build/merapi/cmake-get_filename_component-issue
-- Configuring done
-- Generating done
-- Build files have been written to: /homes/as12312/opt/build/merapi/cmake-get_filename_component-issue

Note that the ABSOLUTE return value of get_filename_component of the real input path contains symbolic links again!

Tags

No tags attached.

Attached Files

CMakeLists.txt [^] (503 bytes) 2015-09-15 11:15 [Show Content] [Hide Content]

cmake_minimum_required(VERSION 2.8.4)

get_filename_component(REAL_SOURCE_DIR "${CMAKE_SOURCE_DIR}" REALPATH)
get_filename_component(SOURCE_DIR      "${REAL_SOURCE_DIR}"  ABSOLUTE)

get_filename_component(REAL_BUILD_DIR "${CMAKE_BINARY_DIR}" REALPATH)
get_filename_component(BUILD_DIR      "${REAL_BUILD_DIR}"   ABSOLUTE)

message ("CMAKE_SOURCE_DIR:\n\tREALPATH = ${REAL_SOURCE_DIR}\n\tABSOLUTE = ${SOURCE_DIR}")
message ("CMAKE_BINARY_DIR:\n\tREALPATH = ${REAL_BUILD_DIR}\n\tABSOLUTE = ${BUILD_DIR}")

Relationships

Notes
(0042838) Kitware Robot (administrator) 2016-06-10 14:29	Resolving issue as `moved`. This issue tracker is no longer used. Further discussion of this issue may take place in the current CMake Issues page linked in the banner at the top of this page.

Issue History
Date Modified	Username	Field	Change
2015-09-15 11:15	Andreas Schuh	New Issue
2015-09-15 11:15	Andreas Schuh	File Added: CMakeLists.txt
2016-06-10 14:29	Kitware Robot	Note Added: 0042838
2016-06-10 14:29	Kitware Robot	Status	new => resolved
2016-06-10 14:29	Kitware Robot	Resolution	open => moved
2016-06-10 14:29	Kitware Robot	Assigned To	=> Kitware Robot
2016-06-10 14:31	Kitware Robot	Status	resolved => closed