daniel has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmocore/+/33685 ) Change subject: osmo_io: Document expectation that segmentation_cb() can modify msgb ...................................................................... osmo_io: Document expectation that segmentation_cb() can modify msgb This is used for parsing e.g. the ipa header and setting msg->cb. Guard against segmentation_cb changing msg->data in iofd_handle_segmentation(). Change-Id: Idd2115baae98a7818aabb26232d4423d2d48fb5c --- M include/osmocom/core/osmo_io.h M src/core/osmo_io.c 2 files changed, 25 insertions(+), 4 deletions(-) git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/85/33685/1 diff --git a/include/osmocom/core/osmo_io.h b/include/osmocom/core/osmo_io.h index 932b909..81f13f2 100644 --- a/include/osmocom/core/osmo_io.h +++ b/include/osmocom/core/osmo_io.h @@ -46,7 +46,10 @@ * Needs to return the size of the next message. If it returns * -EAGAIN or a value larger than msgb_length() (message is incomplete) * osmo_io will wait for more data to be read. Other negative values - * cause the msg to be discarded. */ + * cause the msg to be discarded. If a full message was received the msgb + * will be trimmed to size and forwarded to the read call-back. All parsing + * done to the msgb by the segmentation_cb() for that message will be preserved + * (e.g. setting lxh or msgb->cb). */ int (*segmentation_cb)(struct msgb *msg); }; diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c index fdb9e32..8217316 100644 --- a/src/core/osmo_io.c +++ b/src/core/osmo_io.c @@ -226,6 +226,9 @@ int extra_len, received_len; struct msgb *msg_pending; + /* Save the start of message before segmentation_cb (which could change it) */ + uint8_t *data = msg->data; + received_len = msgb_length(msg); if (!iofd->io_ops.segmentation_cb) { @@ -258,12 +261,14 @@ /* msgb contains more than one segment */ /* Copy the trailing data over */ msg_pending = iofd_msgb_alloc(iofd); - memcpy(msgb_data(msg_pending), msgb_data(msg) + expected_len, extra_len); + memcpy(msgb_data(msg_pending), data + expected_len, extra_len); msgb_put(msg_pending, extra_len); *pending_out = msg_pending; - /* Trim the original msgb to size */ - msgb_trim(msg, expected_len); + /* Trim the original msgb to size. Don't use msgb_trim because we need to reference + * msg->data from before it might have been modified by the segmentation_cb(). */ + msg->len = expected_len; + msg->tail = data + expected_len; return IOFD_SEG_ACT_HANDLE_MORE; defer: -- To view, visit https://gerrit.osmocom.org/c/libosmocore/+/33685 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: libosmocore Gerrit-Branch: master Gerrit-Change-Id: Idd2115baae98a7818aabb26232d4423d2d48fb5c Gerrit-Change-Number: 33685 Gerrit-PatchSet: 1 Gerrit-Owner: daniel <dwillmann(a)sysmocom.de> Gerrit-MessageType: newchange