Re: [PATCH v2 1/2] scripts: Add a recorduidiv program

Steven Rostedt
2015-12-01T17:22:19Z

On Tue, 1 Dec 2015 17:10:14 +0000
Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:

> Another suggestion - maybe recordmcount, which fstat()s the file,
> should check the st_nlink before modifying the file, and error out
> with a helpful error message telling people not to use hardlinks,
> which would stop nasty surprises (and make it a rule that this should
> be implemented as a general principle for good build behaviour) - iow,

Actually I like this solution the best.

> something like this (untested):

Can you test it to see if it gives you the error, otherwise I need to
set up a CCACHE_HARDLINK environment :-)

I guess another solution is to do a copy instead of modifying in place
if it detects the multiple hard link?

-- Steve

>
> scripts/recordmcount.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
> index 698768bdc581..bb7589fd7392 100644
> --- a/scripts/recordmcount.c
> +++ b/scripts/recordmcount.c
> @@ -203,6 +203,10 @@ static void *mmap_file(char const *fname)
> fprintf(stderr, "not a regular file: %s\n", fname);
> fail_file();
> }
> + if (sb.st_nlink != 1) {
> + fprintf(stderr, "file is hard linked: %s\n", fname);
> + fail_file();
> + }
> addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
> fd_map, 0);
> mmap_failed = 0;
>
>