PR c/81117 - Improve buffer overflow checking in strncpy

gcc/ChangeLog:

	PR c/81117
	* builtins.c (compute_objsize): Handle arrays that
	compute_builtin_object_size likes to fail for.  Make extern.
	* builtins.h (compute_objsize): Declare.
	(check_strncpy_sizes): New function.
	(expand_builtin_strncpy): Call check_strncpy_sizes.
	* gimple-fold.c (gimple_fold_builtin_strncpy): Implement
	-Wstringop-truncation.
	(gimple_fold_builtin_strncat): Same.
	* gimple.c (gimple_build_call_from_tree): Set call location.
	* tree-ssa-strlen.c (strlen_to_stridx): New global variable.
	(maybe_diag_bound_equal_length, is_strlen_related_p): New functions.
	(handle_builtin_stxncpy, handle_builtin_strncat): Same.
	(handle_builtin_strlen): Use strlen_to_stridx.
	(strlen_optimize_stmt): Handle flavors of strncat, strncpy, and
	stpncpy.
	Use strlen_to_stridx.
	(pass_strlen::execute): Release strlen_to_stridx.
	* doc/invoke.texi (-Wsizeof-pointer-memaccess): Document enhancement.
	(-Wstringop-truncation): Document new option.

gcc/ada/ChangeLog:

	PR c/81117
	* ada/adadecode.c (__gnat_decode): Use memcpy instead of strncpy.
	* ada/argv.c (__gnat_fill_arg, __gnat_fill_env): Same.

gcc/c-family/ChangeLog:

	PR c/81117
	* c-common.c (catenate_strings): Use memcpy instead of strncpy.
	* c-warn.c (sizeof_pointer_memaccess_warning): Handle arrays.
	* c.opt (-Wstringop-truncation): New option.

gcc/fortran/ChangeLog:

	PR c/81117
	* gcc/fortran/decl.c (build_sym): Use strcpy instead of strncpy.

gcc/objc/ChangeLog:

	PR c/81117
	* objc-encoding.c (encode_type): Use memcpy instead of strncpy.

gcc/testsuite/ChangeLog:

	PR c/81117
	* c-c++-common/Wsizeof-pointer-memaccess3.c: New test.
	* c-c++-common/Wstringop-overflow.c: Same.
	* c-c++-common/Wstringop-truncation.c: Same.
	* c-c++-common/Wsizeof-pointer-memaccess2.c: Adjust.
	* c-c++-common/attr-nonstring-2.c: New test.
	* g++.dg/torture/Wsizeof-pointer-memaccess1.C: Adjust.
	* g++.dg/torture/Wsizeof-pointer-memaccess2.C: Same.
	* gcc.dg/torture/pr63554.c: Same.
	* gcc.dg/Walloca-1.c: Disable macro tracking.

From-SVN: r254630

4 files changed, 21 insertions, 10 deletions

diff --git a/gcc/testsuite/gcc.dg/Walloca-1.c b/gcc/testsuite/gcc.dg/Walloca-1.c
index ad39373..85e9160 100644
--- a/gcc/testsuite/gcc.dg/Walloca-1.c
+++ b/gcc/testsuite/gcc.dg/Walloca-1.c
@@ -1,6 +1,6 @@
 /* { dg-do compile } */
 /* { dg-require-effective-target alloca } */
-/* { dg-options "-Walloca-larger-than=2000 -O2" } */
+/* { dg-options "-Walloca-larger-than=2000 -O2 -ftrack-macro-expansion=0" } */
 
 #define alloca __builtin_alloca
 
diff --git a/gcc/testsuite/gcc.dg/builtin-stpncpy.c b/gcc/testsuite/gcc.dg/builtin-stpncpy.c
index e4290d5..9200798 100644
--- a/gcc/testsuite/gcc.dg/builtin-stpncpy.c
+++ b/gcc/testsuite/gcc.dg/builtin-stpncpy.c
@@ -1,6 +1,6 @@
 /* PR tree-optimization/80669 - Bad -Wstringop-overflow warnings for stpncpy
    { dg-do compile }
-   { dg-options "-O2 -Wall" } */
+   { dg-options "-O2 -Wall -Wno-stringop-truncation" } */
 
 #define SIZE_MAX __SIZE_MAX__
 
@@ -18,7 +18,9 @@ size_t range (size_t min, size_t max)
   return val < min || max < val ? min : val;
 }
 
-/* Verify that no warning is issued for stpncpy with constant size.  */
+/* Verify that no -Wstringop-overflow warning is issued for stpncpy
+   with constant size.  (Some tests cause -Wstringop-truncation and
+   that's expected).  */
 void test_cst (char *d)
 {
   __builtin_stpncpy (d, "123", 0);
@@ -37,7 +39,8 @@ void test_cst (char *d)
 }
 
 
-/* Verify that no warning is issued for stpncpy with size in some range.  */
+/* Verify that no -Wstringop-overflow warning is issued for stpncpy
+   with size in some range.  */
 void test_rng (char *d)
 {
 #define R(min, max) range (min, max)
diff --git a/gcc/testsuite/gcc.dg/torture/Wsizeof-pointer-memaccess1.c b/gcc/testsuite/gcc.dg/torture/Wsizeof-pointer-memaccess1.c
index f9bc57c..cd9dc72 100644
--- a/gcc/testsuite/gcc.dg/torture/Wsizeof-pointer-memaccess1.c
+++ b/gcc/testsuite/gcc.dg/torture/Wsizeof-pointer-memaccess1.c
@@ -1,6 +1,6 @@
 /* Test -Wsizeof-pointer-memaccess warnings.  */
 /* { dg-do compile } */
-/* { dg-options "-Wall -Wno-sizeof-array-argument -Wno-stringop-overflow" } */
+/* { dg-options "-Wall -Wno-sizeof-array-argument -Wno-stringop-overflow -Wno-stringop-truncation" } */
 /* Test just twice, once with -O0 non-fortified, once with -O2 fortified.  */
 /* { dg-skip-if "" { *-*-* }  { "*" } { "-O0" "-O2" } } */
 /* { dg-skip-if "" { *-*-* }  { "-flto" } { "" } } */
@@ -704,12 +704,17 @@ f4 (char *x, char **y, int z, char w[64])
   strncat (w, s2, sizeof (w));		    /* { dg-warning "call is the same expression as the destination; did you mean to provide an explicit length" } */
   stpncpy (w, s1, sizeof (w));		    /* { dg-warning "call is the same expression as the destination; did you mean to provide an explicit length" } */
 
-  /* These are correct, no warning.  */
+  /* These are pointless when the destination is large enough, and
+     cause overflow otherwise.  If the copies are guaranteed to be
+     safe the calls might as well be replaced by strcat(), strcpy(),
+     or memcpy().  */
   const char s3[] = "foobarbaz";
   const char s4[] = "abcde12345678";
-  strncpy (x, s3, sizeof (s3));
-  strncat (x, s4, sizeof (s4));
-  stpncpy (x, s3, sizeof (s3));
+  strncpy (x, s3, sizeof (s3));             /* { dg-warning "call is the same expression as the source; did you mean to use the size of the destination?" } */
+  strncat (x, s4, sizeof (s4));             /* { dg-warning "call is the same expression as the source; did you mean to use the size of the destination?" } */
+  stpncpy (x, s3, sizeof (s3));             /* { dg-warning "call is the same expression as the source; did you mean to use the size of the destination?" } */
+
+  /* These are correct, no warning.  */
   y[1] = strndup (s3, sizeof (s3));
   z += strncmp (s3, s4, sizeof (s3));
   z += strncmp (s3, s4, sizeof (s4));
diff --git a/gcc/testsuite/gcc.dg/torture/pr63554.c b/gcc/testsuite/gcc.dg/torture/pr63554.c
index fa06c5a..9162266 100644
--- a/gcc/testsuite/gcc.dg/torture/pr63554.c
+++ b/gcc/testsuite/gcc.dg/torture/pr63554.c
@@ -1,4 +1,5 @@
-/* { dg-do compile } */
+/* PR c/63554 - ice in "execute_todo, at passes.c:1797" with -O3
+   { dg-do compile } */
 
 char *a;
 void
@@ -7,3 +8,5 @@ nssutil_ReadSecmodDB (void)
   long b = __builtin_object_size (0, 0);
   a = __builtin___strncat_chk (a, " ", 1, b);
 }
+
+/* { dg-prune-output "\\\[-Wstringop-overflow=]" } */