[PATCH v2 4/4] Linux symbol CRCs: support 0 and report presence changes

Matthias Maennich maennich@google.com
Thu Mar 17 12:01:45 GMT 2022


On Wed, Mar 16, 2022 at 04:30:55PM +0000, Giuliano Procida wrote:
>The CRC with value zero was used to mean "absent". This can be better
>modelled using optional.
>
>This commit makes this change and also tweaks reporting so that
>disappearing / appearing CRCs are noted. This should be essentially
>impossible unless CRCs are enabled / disabled altogether but would be
>very noteworthy otherwise.
>
>	* include/abg-ir.h (elf_symbol::elf_symbol): Argument crc is
>	now an optional defaulted to absent.
>	(elf_symbol::create): Likewise.
>	(elf_symbol::get_crc): Now returns an optional uint64_t.
>	(elf_symbol::set_src): Now takes an optional uint64_t.
>	* src/abg-comp-filter.cc (crc_changed): Simplify comparison.
>	* src/abg-ir.cc (elf_symbol::priv): Member crc_ is now an
>	optional uint64_t.
>	(elf_symbol::priv::priv): Argument crc is now an optional
>	uint64_t.
>	(elf_symbol::elf_symbol): Likewise.
>	(elf_symbol::create): Argument crc is now an optional uint64_t
>	and defaults to absent.
>	(textually_equals): Simplify comparison.
>	(elf_symbol::get_crc): Now returns an optional uint64_t.
>	(elf_symbol::set_crc): Now takes an optional uint64_t.
>	* src/abg-reader.cc (build_elf_symbol): Treat CRC 0 the same
>	as other CRC values.
>	* src/abg-reporter-priv.cc (maybe_report_diff_for_symbol):
>	Treat CRC 0 the same as other CRC values and also report
>	changes to CRC presence.
>	* src/abg-writer.cc (write_elf_symbol): Treat CRC 0 the same
>	as other CRC values.
>	* tests/data/Makefile: Remove test-abidiff/test-crc-report.txt
>	and add test-abidiff/test-crc-report-{0-1,1-0,1-2}.txt.
>	* tests/data/test-abidiff/test-crc-report-0-1.txt: Report
>	showing additional of CRCs.
>	* tests/data/test-abidiff/test-crc-report-1-0.txt: Report
>	showing removal of CRCs.
>	* tests/data/test-abidiff/test-crc-report-1-2.txt: Renamed
>	from tests/data/test-abidiff/test-crc-report.txt.
>	* tests/test-abidiff.cc: Update test cases that no longer
>	generate empty reports.
>	* tests/test-symtab.cc: Update KernelSymtabsWithCRC test.
>
>Signed-off-by: Giuliano Procida <gprocida@google.com>

Reviewed-by: Matthias Maennich <maennich@google.com>

Cheers,
Matthias

>---
> include/abg-ir.h                              |  8 ++++----
> src/abg-comp-filter.cc                        |  4 +---
> src/abg-ir.cc                                 | 19 +++++++++---------
> src/abg-reader.cc                             |  8 ++------
> src/abg-reporter-priv.cc                      | 20 ++++++++++++++-----
> src/abg-writer.cc                             |  6 +++---
> tests/data/Makefile.am                        |  4 +++-
> .../data/test-abidiff/test-crc-report-0-1.txt | 16 +++++++++++++++
> .../data/test-abidiff/test-crc-report-1-0.txt | 16 +++++++++++++++
> ...crc-report.txt => test-crc-report-1-2.txt} |  0
> tests/test-abidiff.cc                         |  6 +++---
> tests/test-symtab.cc                          |  8 ++++----
> 12 files changed, 76 insertions(+), 39 deletions(-)
> create mode 100644 tests/data/test-abidiff/test-crc-report-0-1.txt
> create mode 100644 tests/data/test-abidiff/test-crc-report-1-0.txt
> rename tests/data/test-abidiff/{test-crc-report.txt => test-crc-report-1-2.txt} (100%)
>
>diff --git a/include/abg-ir.h b/include/abg-ir.h
>index 7c42bea7..7c558828 100644
>--- a/include/abg-ir.h
>+++ b/include/abg-ir.h
>@@ -921,7 +921,7 @@ private:
> 	     const version&	ve,
> 	     visibility		vi,
> 	     bool		is_in_ksymtab = false,
>-	     uint64_t		crc = 0,
>+	     const abg_compat::optional<uint64_t>&	crc = {},
> 	     const abg_compat::optional<std::string>&	ns = {},
> 	     bool		is_suppressed = false);
>
>@@ -947,7 +947,7 @@ public:
> 	 const version&	    ve,
> 	 visibility	    vi,
> 	 bool		    is_in_ksymtab = false,
>-	 uint64_t	    crc = 0,
>+	 const abg_compat::optional<uint64_t>&		crc = {},
> 	 const abg_compat::optional<std::string>&	ns = {},
> 	 bool		    is_suppressed = false);
>
>@@ -1020,11 +1020,11 @@ public:
>   void
>   set_is_in_ksymtab(bool is_in_ksymtab);
>
>-  uint64_t
>+  const abg_compat::optional<uint64_t>&
>   get_crc() const;
>
>   void
>-  set_crc(uint64_t crc);
>+  set_crc(const abg_compat::optional<uint64_t>& crc);
>
>   const abg_compat::optional<std::string>&
>   get_namespace() const;
>diff --git a/src/abg-comp-filter.cc b/src/abg-comp-filter.cc
>index c179b6bd..22da5244 100644
>--- a/src/abg-comp-filter.cc
>+++ b/src/abg-comp-filter.cc
>@@ -234,9 +234,7 @@ crc_changed(const function_or_var_decl_sptr& f,
>   const auto& symbol_s = s->get_symbol();
>   if (!symbol_f || !symbol_s)
>     return false;
>-  const auto crc_f = symbol_f->get_crc();
>-  const auto crc_s = symbol_s->get_crc();
>-  return crc_f != 0 && crc_s != 0 && crc_f != crc_s;
>+  return symbol_f->get_crc() != symbol_s->get_crc();
> }
>
> /// Test if the current diff tree node carries a CRC change in either a
>diff --git a/src/abg-ir.cc b/src/abg-ir.cc
>index 78154622..f90be2e4 100644
>--- a/src/abg-ir.cc
>+++ b/src/abg-ir.cc
>@@ -1727,7 +1727,7 @@ struct elf_symbol::priv
>   //     STT_COMMON definition of that name that has the largest size.
>   bool			is_common_;
>   bool			is_in_ksymtab_;
>-  uint64_t		crc_;
>+  abg_compat::optional<uint64_t>	crc_;
>   abg_compat::optional<std::string>	namespace_;
>   bool			is_suppressed_;
>   elf_symbol_wptr	main_symbol_;
>@@ -1745,7 +1745,7 @@ struct elf_symbol::priv
>       is_defined_(false),
>       is_common_(false),
>       is_in_ksymtab_(false),
>-      crc_(0),
>+      crc_(),
>       namespace_(),
>       is_suppressed_(false)
>   {}
>@@ -1761,7 +1761,7 @@ struct elf_symbol::priv
>        const elf_symbol::version& ve,
>        elf_symbol::visibility	  vi,
>        bool			  is_in_ksymtab,
>-       uint64_t			  crc,
>+       const abg_compat::optional<uint64_t>&	crc,
>        const abg_compat::optional<std::string>&	ns,
>        bool			  is_suppressed)
>     : env_(e),
>@@ -1835,7 +1835,7 @@ elf_symbol::elf_symbol(const environment* e,
> 		       const version&	  ve,
> 		       visibility	  vi,
> 		       bool		  is_in_ksymtab,
>-		       uint64_t		  crc,
>+		       const abg_compat::optional<uint64_t>&	crc,
> 		       const abg_compat::optional<std::string>&	ns,
> 		       bool		  is_suppressed)
>   : priv_(new priv(e,
>@@ -1910,7 +1910,7 @@ elf_symbol::create(const environment* e,
> 		   const version&     ve,
> 		   visibility	      vi,
> 		   bool		      is_in_ksymtab,
>-		   uint64_t	      crc,
>+		   const abg_compat::optional<uint64_t>&	crc,
> 		   const abg_compat::optional<std::string>&	ns,
> 		   bool		      is_suppressed)
> {
>@@ -1937,8 +1937,7 @@ textually_equals(const elf_symbol&l,
> 		 && l.is_defined() == r.is_defined()
> 		 && l.is_common_symbol() == r.is_common_symbol()
> 		 && l.get_version() == r.get_version()
>-		 && (l.get_crc() == 0 || r.get_crc() == 0
>-		     || l.get_crc() == r.get_crc())
>+		 && l.get_crc() == r.get_crc()
> 		 && l.get_namespace() == r.get_namespace());
>
>   if (equals && l.is_variable())
>@@ -2147,8 +2146,8 @@ elf_symbol::set_is_in_ksymtab(bool is_in_ksymtab)
>
> /// Getter of the 'crc' property.
> ///
>-/// @return the CRC (modversions) value for Linux Kernel symbols (if present)
>-uint64_t
>+/// @return the CRC (modversions) value for Linux Kernel symbols, if any
>+const abg_compat::optional<uint64_t>&
> elf_symbol::get_crc() const
> {return priv_->crc_;}
>
>@@ -2156,7 +2155,7 @@ elf_symbol::get_crc() const
> ///
> /// @param crc the new CRC (modversions) value for Linux Kernel symbols
> void
>-elf_symbol::set_crc(uint64_t crc)
>+elf_symbol::set_crc(const abg_compat::optional<uint64_t>& crc)
> {priv_->crc_ = crc;}
>
> /// Getter of the 'namespace' property.
>diff --git a/src/abg-reader.cc b/src/abg-reader.cc
>index 0a8ecd70..f9e420f1 100644
>--- a/src/abg-reader.cc
>+++ b/src/abg-reader.cc
>@@ -3239,10 +3239,6 @@ build_elf_symbol(read_context& ctxt, const xmlNodePtr node,
> 	is_default_version = true;
>     }
>
>-  uint64_t crc = 0;
>-  if (xml_char_sptr s = XML_NODE_GET_ATTRIBUTE(node, "crc"))
>-    crc = strtoull(CHAR_STR(s), NULL, 0);
>-
>   elf_symbol::type type = elf_symbol::NOTYPE_TYPE;
>   read_elf_symbol_type(node, type);
>
>@@ -3266,8 +3262,8 @@ build_elf_symbol(read_context& ctxt, const xmlNodePtr node,
>
>   e->set_is_suppressed(is_suppressed);
>
>-  if (crc != 0)
>-    e->set_crc(crc);
>+  if (xml_char_sptr s = XML_NODE_GET_ATTRIBUTE(node, "crc"))
>+    e->set_crc(strtoull(CHAR_STR(s), NULL, 0));
>
>   if (xml_char_sptr s = XML_NODE_GET_ATTRIBUTE(node, "namespace"))
>     {
>diff --git a/src/abg-reporter-priv.cc b/src/abg-reporter-priv.cc
>index 9ebcdf00..9ad733f4 100644
>--- a/src/abg-reporter-priv.cc
>+++ b/src/abg-reporter-priv.cc
>@@ -1149,13 +1149,23 @@ maybe_report_diff_for_symbol(const elf_symbol_sptr&	symbol1,
> 	  << "\n";
>     }
>
>-  if (symbol1->get_crc() != 0 && symbol2->get_crc() != 0
>-      && symbol1->get_crc() != symbol2->get_crc())
>+  const abg_compat::optional<uint64_t>& crc1 = symbol1->get_crc();
>+  const abg_compat::optional<uint64_t>& crc2 = symbol2->get_crc();
>+  if (crc1 != crc2)
>     {
>+      const std::string none = "(none)";
>       out << indent << "CRC (modversions) changed from "
>-	  << std::showbase << std::hex
>-	  << symbol1->get_crc() << " to " << symbol2->get_crc()
>-	  << std::noshowbase << std::dec
>+	  << std::showbase << std::hex;
>+      if (crc1.has_value())
>+	out << crc1.value();
>+      else
>+	out << none;
>+      out << " to ";
>+      if (crc2.has_value())
>+	out << crc2.value();
>+      else
>+	out << none;
>+      out << std::noshowbase << std::dec
> 	  << "\n";
>     }
>
>diff --git a/src/abg-writer.cc b/src/abg-writer.cc
>index 692abc75..03fb658b 100644
>--- a/src/abg-writer.cc
>+++ b/src/abg-writer.cc
>@@ -3131,10 +3131,10 @@ write_elf_symbol(const elf_symbol_sptr&	sym,
>   if (sym->is_common_symbol())
>     o << " is-common='yes'";
>
>-  if (sym->get_crc() != 0)
>+  if (sym->get_crc().has_value())
>     o << " crc='"
>-      << std::hex << std::showbase << sym->get_crc() << "'"
>-      << std::dec << std::noshowbase;
>+      << std::hex << std::showbase << sym->get_crc().value()
>+      << std::dec << std::noshowbase << "'";
>
>   if (sym->get_namespace().has_value())
>     o << " namespace='" << sym->get_namespace().value() << "'";
>diff --git a/tests/data/Makefile.am b/tests/data/Makefile.am
>index 7ea24d58..7388697b 100644
>--- a/tests/data/Makefile.am
>+++ b/tests/data/Makefile.am
>@@ -90,7 +90,9 @@ test-abidiff/test-empty-corpus-2.xml		\
> test-abidiff/test-crc-0.xml \
> test-abidiff/test-crc-1.xml \
> test-abidiff/test-crc-2.xml \
>-test-abidiff/test-crc-report.txt \
>+test-abidiff/test-crc-report-0-1.txt \
>+test-abidiff/test-crc-report-1-0.txt \
>+test-abidiff/test-crc-report-1-2.txt \
> test-abidiff/test-namespace-0.xml \
> test-abidiff/test-namespace-1.xml \
> test-abidiff/test-namespace-report.txt \
>diff --git a/tests/data/test-abidiff/test-crc-report-0-1.txt b/tests/data/test-abidiff/test-crc-report-0-1.txt
>new file mode 100644
>index 00000000..0db42f68
>--- /dev/null
>+++ b/tests/data/test-abidiff/test-crc-report-0-1.txt
>@@ -0,0 +1,16 @@
>+Functions changes summary: 0 Removed, 1 Changed, 0 Added function
>+Variables changes summary: 0 Removed, 2 Changed, 0 Added variables
>+
>+1 function with some indirect sub-type change:
>+
>+  [C] 'function void exported_function()' has some indirect sub-type changes:
>+    CRC (modversions) changed from (none) to 0xe52d5bcf
>+
>+2 Changed variables:
>+
>+  [C] 'int exported_variable' was changed:
>+    CRC (modversions) changed from (none) to 0xee94d699
>+
>+  [C] 'int exported_variable_gpl' was changed:
>+    CRC (modversions) changed from (none) to 0x41336c46
>+
>diff --git a/tests/data/test-abidiff/test-crc-report-1-0.txt b/tests/data/test-abidiff/test-crc-report-1-0.txt
>new file mode 100644
>index 00000000..e11f29c1
>--- /dev/null
>+++ b/tests/data/test-abidiff/test-crc-report-1-0.txt
>@@ -0,0 +1,16 @@
>+Functions changes summary: 0 Removed, 1 Changed, 0 Added function
>+Variables changes summary: 0 Removed, 2 Changed, 0 Added variables
>+
>+1 function with some indirect sub-type change:
>+
>+  [C] 'function void exported_function()' has some indirect sub-type changes:
>+    CRC (modversions) changed from 0xe52d5bcf to (none)
>+
>+2 Changed variables:
>+
>+  [C] 'int exported_variable' was changed:
>+    CRC (modversions) changed from 0xee94d699 to (none)
>+
>+  [C] 'int exported_variable_gpl' was changed:
>+    CRC (modversions) changed from 0x41336c46 to (none)
>+
>diff --git a/tests/data/test-abidiff/test-crc-report.txt b/tests/data/test-abidiff/test-crc-report-1-2.txt
>similarity index 100%
>rename from tests/data/test-abidiff/test-crc-report.txt
>rename to tests/data/test-abidiff/test-crc-report-1-2.txt
>diff --git a/tests/test-abidiff.cc b/tests/test-abidiff.cc
>index 009f7de5..93e44d6a 100644
>--- a/tests/test-abidiff.cc
>+++ b/tests/test-abidiff.cc
>@@ -113,19 +113,19 @@ static InOutSpec specs[] =
>   {
>     "data/test-abidiff/test-crc-0.xml",
>     "data/test-abidiff/test-crc-1.xml",
>-    "data/test-abidiff/empty-report.txt",
>+    "data/test-abidiff/test-crc-report-0-1.txt",
>     "output/test-abidiff/test-crc-report-0-1.txt"
>   },
>   {
>     "data/test-abidiff/test-crc-1.xml",
>     "data/test-abidiff/test-crc-0.xml",
>-    "data/test-abidiff/empty-report.txt",
>+    "data/test-abidiff/test-crc-report-1-0.txt",
>     "output/test-abidiff/test-crc-report-1-0.txt"
>   },
>   {
>     "data/test-abidiff/test-crc-1.xml",
>     "data/test-abidiff/test-crc-2.xml",
>-    "data/test-abidiff/test-crc-report.txt",
>+    "data/test-abidiff/test-crc-report-1-2.txt",
>     "output/test-abidiff/test-crc-report-1-2.txt"
>   },
>   {
>diff --git a/tests/test-symtab.cc b/tests/test-symtab.cc
>index 7d7a2df0..85303563 100644
>--- a/tests/test-symtab.cc
>+++ b/tests/test-symtab.cc
>@@ -420,9 +420,9 @@ TEST_CASE("Symtab::KernelSymtabsWithCRC", "[symtab, crc, kernel, ksymtab]")
>   {
>     const std::string  binary = base_path + "one_of_each.ko";
>     const corpus_sptr& corpus = assert_symbol_count(binary, 2, 2);
>-    CHECK(corpus->lookup_function_symbol("exported_function")->get_crc() != 0);
>-    CHECK(corpus->lookup_function_symbol("exported_function_gpl")->get_crc() != 0);
>-    CHECK(corpus->lookup_variable_symbol("exported_variable")->get_crc() != 0);
>-    CHECK(corpus->lookup_variable_symbol("exported_variable_gpl")->get_crc() != 0);
>+    CHECK(corpus->lookup_function_symbol("exported_function")->get_crc());
>+    CHECK(corpus->lookup_function_symbol("exported_function_gpl")->get_crc());
>+    CHECK(corpus->lookup_variable_symbol("exported_variable")->get_crc());
>+    CHECK(corpus->lookup_variable_symbol("exported_variable_gpl")->get_crc());
>   }
> }
>-- 
>2.35.1.894.gb6a874cedc-goog
>


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