[Bug 11215] New: compression/zlib errors discard the zlib error message

[samba-bugs at samba.org]

https://bugzilla.samba.org/show_bug.cgi?id=11215

            Bug ID: 11215
           Summary: compression/zlib errors discard the zlib error message
           Product: rsync
           Version: 3.1.0
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P5
         Component: core
          Assignee: wayned at samba.org
          Reporter: treffer at measite.de
        QA Contact: rsync-qa at samba.org

We recently experienced a rsync failure:

inflate returned -3 (0 bytes)
rsync error: error in rsync protocol data stream (code 12) at token.c(557)
[receiver=3.1.0]
rsync: connection unexpectedly closed (59265966 bytes received so far)
[generator]
rsync error: error in rsync protocol data stream (code 12) at io.c(226)
[generator=3.1.0]

The first error (inflate returned -3 (0 bytes)) was tracked in token.c:

>                 case r_inflating:
>                        rx_strm.next_out = (Bytef *)dbuf;
>                        rx_strm.avail_out = AVAIL_OUT_SIZE(CHUNK_SIZE);
>                        r = inflate(&rx_strm, Z_NO_FLUSH);
>                        n = AVAIL_OUT_SIZE(CHUNK_SIZE) - rx_strm.avail_out;
>                        if (r != Z_OK) {
>                                rprintf(FERROR, "inflate returned %d (%d bytes)\n", r, n);
>                                exit_cleanup(RERR_STREAMIO);
>                        }
>                        if (rx_strm.avail_in == 0)
>                                recv_state = r_inflated;
>                        if (n != 0) {
>                                *data = dbuf;
>                                return n;
>                        }
>                        break;

The problem is that -3 refers to Z_DATA_ERROR. This error is returned whenever
the zlib state machine enters the "BAD" state (inflate.c), e.g.

>        case HCRC:
>            if (state->flags & 0x0200) {
>                NEEDBITS(16);
>                if (hold != (state->check & 0xffff)) {
>                    strm->msg = (char *)"header crc mismatch";
>                    state->mode = BAD;
>                    break;
>                }
>                INITBITS();
>            }

Note that zlib does have an error message in addition to the error code.

It would be very nice if rsync could print the zlib error message alongside the
error code and result buffer size. I currently can't get enough information
from the provided error message to decide if it's an rsync/zlib problem (very
unlikely IMHO) or a hardware issue.

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