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Update comments about tvbuff. 

svn path=/trunk/; revision=41615
This commit is contained in:
Bill Meier 2012-03-16 15:43:56 +00:00
parent 744e6efd2f
commit d18d7413f9
1 changed files with 21 additions and 16 deletions
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37
epan/tvbuff.h
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@ -69,24 +69,29 @@ typedef struct tvbuff tvbuff_t;
*
* Consider a collection of tvbs as being a chain or stack of tvbs.
*
* The top-level dissector (packet.c) pushes the initial tvb onto the stack
* (starts the chain) and then calls a sub-dissector which in turn calls the next
* sub-dissector and so on. Each sub-dissector may chain additional tvbs to
* the tvb handed to that dissector. After dissection is complete and control has
* returned to the top-level dissector, the chain of tvbs (stack) is free'd
* via a call to tvb_free_chain() (in epan_dissect_cleanup()).
* When dissecting a frame:
* The top-level dissector (packet.c) pushes the initial tvb (containing
* the complete frame) onto the stack (starts the chain) and then calls
* a sub-dissector which in turn calls the next sub-dissector and so on.
* Each sub-dissector may chain additional tvbs (see below) to the tvb
* handed to that dissector. After dissection is complete and control has
* returned to the top-level dissector, the chain of tvbs (stack) is free'd
* via a call to tvb_free_chain() (in epan_dissect_cleanup()).
*
* A dissector:
* - Can chain new tvbs (real, subset, composite) to the tvb
* handed to the dissector via tvb_subset(), tvb_new_child_real_data(), etc.
* (Subset and Composite tvbs should reference only tvbs which are
* already part of the chain).
* - Must not save a pointer to a tvb handed to the dissector for
* use when dissecting another frame; A higher level function
* may very well free the chain). This also applies to any tvbs chained
* by the dissector to the tvb handed to the dissector.
* - Can create its own tvb chain (using tvb_new_real_data() which
* the dissector is free to manage as desired. */
* - Can chain new tvbs (subset, real, composite) to the
* tvb handed to the dissector using tvb_new_subset(),
* tvb_new_subset_remaining(), tvb_new_child_real_data(),
* tvb_set_child_real_data_tvbuff(), tvb_composite_finalize(), and
* tvb_child_uncompress(). (Composite tvbs should reference
* only tvbs which are already part of the chain).
* - Must not save for later use (e.g., when dissecting another frame) a
* pointer to a tvb handed to the dissector; (A higher level function
* may very well free the chain thus leaving a dangling pointer).
* This (obviously) also applies to any tvbs chained to the tvb handed
* to the dissector.
* - Can create its own tvb chain (using tvb_new_real_data() which the
* dissector is free to manage as desired. */
/** TVBUFF_REAL_DATA contains a guint8* that points to real data.
* The data is allocated and contiguous.