RFR: 8364312: debug agent should set FD_CLOEXEC flag rather than explicitly closing every open file [v3]

[Kevin Walls]

On Tue, 5 Aug 2025 10:32:42 GMT, Guanqiang Han <ghan at openjdk.org> wrote:

>> Create a new function that marks all file descriptors found in /proc/self/fd with the FD_CLOEXEC flag to ensure they are automatically closed upon execution of a new program via exec().
>
> Guanqiang Han has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - a small fix
>  - Merge remote-tracking branch 'upstream/master' into 8364312
>  - Update exec_md.c
>    
>    correct an compilation error
>  - 8364312: debug agent should set FD_CLOEXEC flag rather than explicitly closing every open file
>    
>    Create a new function that marks all file descriptors found in /proc/self/fd with the FD_CLOEXEC flag to ensure they are automatically closed upon execution of a new program via exec().

src/jdk.jdwp.agent/unix/native/libjdwp/exec_md.c line 59:

> 57: #else
> 58:   #define FD_DIR "/proc/self/fd"
> 59: #endif

Nitpicking, but this FD_DIR define now has a function between its definition here, and where it's used in markDescriptorsCloseOnExec.  It would make sense to move it down to be just before that function.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26568#discussion_r2256793737