analyzer: handle "pipe" and "pipe2" [PR106300]

analyzer: handle "pipe" and "pipe2" [PR106300]

gcc/analyzer/ChangeLog:
	PR analyzer/106300
	* engine.cc (impl_region_model_context::get_fd_map): New.
	* exploded-graph.h (impl_region_model_context::get_fd_map): New
	decl.
	* region-model-impl-calls.cc (region_model::impl_call_pipe): New.
	* region-model.cc (region_model::update_for_int_cst_return): New,
	based on...
	(region_model::update_for_zero_return): ...this.  Reimplement in
	terms of the former.
	(region_model::on_call_pre): Handle "pipe" and "pipe2".
	(region_model::on_call_post): Likewise.
	* region-model.h (region_model::impl_call_pipe): New decl.
	(region_model::update_for_int_cst_return): New decl.
	(region_model::mark_as_valid_fd): New decl.
	(region_model_context::get_fd_map): New pure virtual fn.
	(noop_region_model_context::get_fd_map): New.
	(region_model_context_decorator::get_fd_map): New.
	* sm-fd.cc: Include "analyzer/program-state.h".
	(fd_state_machine::describe_state_change): Handle transitions from
	start state to valid states.
	(fd_state_machine::mark_as_valid_fd): New.
	(fd_state_machine::on_stmt): Add missing return for "creat".
	(region_model::mark_as_valid_fd): New.

gcc/ChangeLog:
	PR analyzer/106300
	* doc/invoke.texi (Static Analyzer Options): Add "pipe" and
	"pipe2" to the list of functions the analyzer has hardcoded
	knowledge of.

gcc/testsuite/ChangeLog:
	PR analyzer/106300
	* gcc.dg/analyzer/pipe-1.c: New test.
	* gcc.dg/analyzer/pipe-glibc.c: New test.
	* gcc.dg/analyzer/pipe-manpages.c: New test.
	* gcc.dg/analyzer/pipe2-1.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>