[Bug 66332] New: drmHandleEvent returns 0 on read() failure

[Bug 66332] New: drmHandleEvent returns 0 on read() failure

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=66332

          Priority: medium
            Bug ID: 66332
          Assignee: dri-devel@lists.freedesktop.org
           Summary: drmHandleEvent returns 0 on read() failure
          Severity: normal
    Classification: Unclassified
                OS: All
          Reporter: mgold@qnx.com
          Hardware: All
            Status: NEW
           Version: XOrg CVS
         Component: libdrm
           Product: DRI

drmHandleEvent contains this code:
        len = read(fd, buffer, sizeof buffer);
        if (len == 0)
                return 0;
        if (len < sizeof *e)
                return -1;
In the (len < sizeof *e) check, len gets promoted to size_t (which is
unsigned); so when len is negative "return -1" won't be executed. Instead, the
function continues to the end and returns 0. (The documentation states
drmHandleEvent will return -1 if the read fails.)

If there's an error like EBADF, the caller won't detect it and might end up
busy-waiting. Rewriting the condition as (len < (int)(sizeof *e)) will fix
this.

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[Bug 66332] drmHandleEvent returns 0 on read() failure

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=66332

GitLab Migration User <gitlab-migration@fdo.invalid> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |MOVED
             Status|NEW                         |RESOLVED

--- Comment #1 from GitLab Migration User <gitlab-migration@fdo.invalid> ---
-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been
closed from further activity.

You can subscribe and participate further through the new bug through this link
to our GitLab instance: https://gitlab.freedesktop.org/mesa/drm/issues/11.

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