i just realised "the hard way" that AST_LIST_INSERT_TAIL can only
append a single element to a list, and it is not good for appending
two lists. The macro also assumes that the element has the 'tail'
pointer properly initialized.
I am not 100% sure that all places in asterisk where AST_LIST_INSERT_TAIL
is used honor the assumption.
Other than a scrutiny of all places where AST_LIST_INSERT_TAIL is used,
i would suggest a simple fix - changing the macro to handle the case
of list merging, as follows (more or less):
#define AST_LIST_INSERT_TAIL(head, elm, field) do { \
if (!(head)->first) { \
(head)->first = (elm); \
} else { \
(head)->last->field.next = (elm); \
} \
(head)->last = (elm); \
while ((head)->last->field.next) \
(head)->last = (head)->last->field.next; \
} while (0)
The extra overhead is negligible in the normal case
((head)->last->field.next = NULL)
Of course, with all these pointer dereferences, one wonders if it
isn't better/safer to use the macro just as a frontend to a
function, using offsetof(field) to locate link field within the
structure.
cheers
luigi
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