The BUG_ON_HOT() test condition added to b_peek_varint() by commit
8873b85bd ("DEBUG: buf: add BUG_ON_HOT() to most buffer management
functions") was wrong as <data> in this function is not b->data,
so that was triggering during live dumps of H2 traces on the CLI
when built with -DDEBUG_STRICT=2. No backport is needed.
A number of tests are now performed in low-level buffer management
functions to verify that we're not appending data to a full buffer
for example, or that the buffer passed in argument is consistent in
that its data don't outweigh its size. The few functions that already
involve memcpy() or memmove() instead got a BUG_ON() that will always
be enabled, since the overhead remains minimalist.
The buffer ring management functions br_* were all stuffed with BUG_ON()
statements that never triggered and that are on some fast paths (e.g. in
mux_h2). Let's turn them to BUG_ON_HOT() instead.
A bogus test in b_get_varint(), b_put_varint(), b_peek_varint() shifts
the end of the buffer by one byte. Since the bug is the same in the read
and write functions, the buffer contents remain compatible, which explains
why this bug was not detected earlier. But if the buffer ends on an
aligned address or page, it can result in a one-byte overflow which will
typically cause a crash or an inconsistent behavior.
This API is only used by rings (e.g. for traces and boot messages) and
by DNS responses, so the probability to hit it is extremely low, but a
crash on boot was observed.
This must be backported to 2.2.
This function does exactly the same thing as b_xfer() which transfers
data from a struct buffer to another one but without zero copy when
the destination buffer is empty. This is at least useful to transfer
h3 data to the QUIC mux from buffer with garbage medata which have
been used to build h3 frames without too much memcopy()/memmove().
b_slow_realign() function may be used to realign a buffer with a given
amount of output data, eventually 0. In such case, the head is set to
0. This function is not designed to be used with input only buffers, like
those used in the muxes. It is the purpose of b_slow_realign_ofs()
function. It does almost the same, realign a buffer. But it do so by setting
the buffer head to a specific offset.
File buf.h is one common cause of pain in the dependencies. Many files in
the code need it to get the struct buffer definition, and a few also need
the inlined functions to manipulate a buffer, but the file used to depend
on a long chain only for BUG_ON() (addressed by last commit).
Now buf.h is split into buf-t.h which only contains the type definitions,
and buf.h for all inlined functions. Callers who don't care can continue
to use buf.h but files in types/ must only use buf-t.h. sys/types.h had
to be added to buf.h to get ssize_t as used by b_move(). It's worth noting
that ssize_t is only supposed to be a size_t supporting -1, so b_move()
ought to be rethought regarding this.
The files were moved to haproxy/ and all their users were updated
accordingly. A dependency issue was addressed on fcgi whose C file didn't
include buf.h.
