c-common.c (check_format_info): Warn for non-constant format strings with strftime formats if -Wformat-nonliteral.

	* c-common.c (check_format_info): Warn for non-constant format
	strings with strftime formats if -Wformat-nonliteral.  Where the
	format can convert arguments, if the format is not a string
	literal and there are no arguments to the format, give a different
	warning message from the general non-string-literal case.

testsuite:
	* gcc.dg/format-nonlit-3.c: New test.

From-SVN: r38105

4 files changed, 51 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2119c93..ab777ca 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,13 @@
 2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>
 
+	* c-common.c (check_format_info): Warn for non-constant format
+	strings with strftime formats if -Wformat-nonliteral.  Where the
+	format can convert arguments, if the format is not a string
+	literal and there are no arguments to the format, give a different
+	warning message from the general non-string-literal case.
+
+2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>
+
 	* c-common.c (format_wanted_type): Add reading_from_flag.
 	(print_char_table): Mark %s and %S formats with flag "R".
 	(check_format_info_main): Set up reading_from_flag appropriately.
diff --git a/gcc/c-common.c b/gcc/c-common.c
index 7359b04..5e7666a 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -2345,8 +2345,29 @@ check_format_info (status, info, params)
       /* Functions taking a va_list normally pass a non-literal format
 	 string.  These functions typically are declared with
 	 first_arg_num == 0, so avoid warning in those cases.  */
-      if (info->first_arg_num != 0 && warn_format_nonliteral)
-	status_warning (status, "format not a string literal, argument types not checked");
+      if (!(format_types[info->format_type].flags & FMT_FLAG_ARG_CONVERT))
+	{
+	  /* For strftime-like formats, warn for not checking the format
+	     string; but there are no arguments to check.  */
+	  if (warn_format_nonliteral)
+	    status_warning (status, "format not a string literal, format string not checked");
+	}
+      else if (info->first_arg_num != 0)
+	{
+	  /* If there are no arguments for the format at all, we may have
+	     printf (foo) which is likely to be a security hole.  */
+	  while (arg_num + 1 < info->first_arg_num)
+	    {
+	      if (params == 0)
+		break;
+	      params = TREE_CHAIN (params);
+	      ++arg_num;
+	    }
+	  if (params == 0 && warn_format_nonliteral)
+	    status_warning (status, "format not a string literal and no format arguments");
+	  else if (warn_format_nonliteral)
+	    status_warning (status, "format not a string literal, argument types not checked");
+	}
     }
 
   /* If there were extra arguments to the format, normally warn.  However,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 444f2d6..d597494 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>
 
+	* gcc.dg/format-nonlit-3.c: New test.
+
+2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>
+
 	* gcc.dg/c90-printf-1.c: Add test for printf formats reading
 	through a null pointer.
 
diff --git a/gcc/testsuite/gcc.dg/format-nonlit-3.c b/gcc/testsuite/gcc.dg/format-nonlit-3.c
new file mode 100644
index 0000000..4423151
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/format-nonlit-3.c
@@ -0,0 +1,16 @@
+/* Test for warnings for non-string-literal formats.  Test for strftime formats.  */
+/* Origin: Joseph Myers <jsm28@cam.ac.uk> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat -Wformat-nonliteral" } */
+
+typedef __SIZE_TYPE__ size_t;
+
+struct tm;
+
+extern size_t strftime (char *, size_t, const char *, const struct tm *);
+
+void
+foo (char *s, size_t m, const struct tm *tp, char *fmt)
+{
+  strftime (s, m, fmt, tp); /* { dg-warning "format string" "non-literal" } */
+}