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

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* 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
This commit is contained in:
Joseph Myers 2000-12-07 07:52:20 +00:00 • committed by Joseph Myers
parent 014e7f1d30
commit 1c248308f4
4 changed files with 51 additions and 2 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
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.

25
gcc/c-common.c
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@ -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,

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
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

16
gcc/testsuite/gcc.dg/format-nonlit-3.c Normal file
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@ -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" } */
}