Hi Randal

[cc'ing Patrick for the reftable writer]

On 25/02/2024 20:36, rsbecker@nexbridge.com wrote:

On Sunday, February 25, 2024 2:20 PM, Torsten Bögershausen wrote:

quoted

On Sun, Feb 25, 2024 at 02:08:35PM -0500, rsbecker@nexbridge.com wrote:

quoted

On Sunday, February 25, 2024 1:45 PM, I wrote:

quoted

To: git@vger.kernel.org

But I think that this should be used:
write_in_full()

My mailer autocorrected, yes, xwrite. write_in_full() would be safe,
although a bit redundant since xwrite() does similar things and is used by
write_in_full().

Note that unlike write_in_full(), xwrite() does not guarantee to write 
the whole buffer passed to it. In general unless a caller is writing a 
single byte or writing less than PIPE_BUF bytes to a pipe it should use 
write_in_full().

The question is which call is bad? The cruft stuff is
relatively new and I don't know the code.

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reftable/writer.c:              int n = w->write(w->write_arg, zeroed,
w->pending_padding);
reftable/writer.c:      n = w->write(w->write_arg, data, len);

Neither of these appear to check for short writes and 
reftable_fd_write() is a thin wrapper around write(). Maybe 
reftable_fd_write() should be using write_in_full()?

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run-command.c:                  len = write(io->fd, io->u.out.buf,

This call to write() looks correct as it is in the io pump loop.

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t/helper/test-path-utils.c:                     if (write(1, buffer,

count)

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< 0) >>> t/helper/test-windows-named-pipe.c:             write(1, buf, nbr);
t/helper/test-windows-named-pipe.c:             write(1, buf, nbr);

In principle these all look like they are prone to short writes.

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trace2/tr2_dst.c:       bytes = write(fd, buf_line->buf, buf_line->len);

This caller explicitly says it prefers short writes over retrying

Best Wishes

Phillip