cmake: fix relative path calculate error #74710
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The build directory absolutely is local generated directory, not public for other. |
No, the build directory is not "100% private": to make sure the build is reproducible you need to compare object files. Reproducible builds are important for security, for instance they help with "JiaT75" issues. Comparing build directories also helps catching small but harmful differences between CI and developers and between developers. For more context see #50205, #14593, https://www.cisa.gov/sbom, https://reproducible-builds.org/ etc. |
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This removes the use of relative path which was intentionally added in #16368.
This is indeed a logical revert of d1b4da9, so at least the commit message is wrong. It currently says "fix relative path calculate error" but this commit does not fix any "calculate error", instead it reverts to an absolute, non reproducible path.
Thanks @ithinuel for the good catch.
```C
file(RELATIVE_PATH relpath ${ZEPHYR_BASE}/include ${path})
```
The prerequisite path assumed here must be the prefix of ZEPHYR,
but if use symbolic links it will calculate error: like this:
zephyrproject-rtos#74647 (comment)
Fixes: zephyrproject-rtos#74647
Signed-off-by: Lingao Meng <[email protected]>
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| get_filename_component(ZEPHYR_BASE_REALPATH "${ZEPHYR_BASE}/include" REALPATH) | ||
| get_filename_component(PATH_REALPATH "${path}" REALPATH) |
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The command get_filename_component(... REALPATH) has been superseded by file(REAL_PATH ...) cmake.
get_filename_componentGet a specific component of a full filename.
Changed in version 3.20: This command has been superseded by the cmake_path() command, except for REALPATH, which is now offered by file(REAL_PATH),
https://cmake.org/cmake/help/latest/command/get_filename_component.html#command:cmake_path
but please note that file(REAL_PATH ...) is affected by CMP0152., and before you ask, then yes, get_filename_component(... REAL_PATH) suffers the same issue related to symlink resolving, but doesn't have a policy for controlling this (always fixed at OLD behavior).
Which again shows that the use of symlinks can be tricky.
Also, variables intended for local use should be written in lowercase, like path_realpath and zephyr_base_realpath.
And please use another name than zephyr_base_realpath, as it is not the real path of Zephyr you are defining, but a subfolder (include).
Fixes #74647