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Add support for a new archetype "printf0" for the "format" function

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attribute.  It is like the existing "printf" archetype, except that
it doesn't complain if the format string is a null pointer.  See
the node "Function Attributes" in the GCC info pages if you don't
know what this is all about.

This change will allow us to add format string checking for the
err(3) family of functions.
This commit is contained in:
John Polstra 1998-07-15 04:22:45 +00:00
parent 15c7382561
commit 3bc25faee6
3 changed files with 46 additions and 23 deletions
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51
contrib/gcc/c-common.c
View File

@ -536,6 +536,7 @@ decl_attributes (node, attributes, prefix_attributes)
int format_num;
int first_arg_num;
int is_scan;
int null_format_ok;
tree argument;
int arg_num;
@ -550,15 +551,30 @@ decl_attributes (node, attributes, prefix_attributes)
&& (!strcmp (IDENTIFIER_POINTER (format_type), "printf")
|| !strcmp (IDENTIFIER_POINTER (format_type),
"__printf__")))
is_scan = 0;
{
is_scan = 0;
null_format_ok = 0;
}
else if (TREE_CODE (format_type) == IDENTIFIER_NODE
&& (!strcmp (IDENTIFIER_POINTER (format_type), "printf0")
|| !strcmp (IDENTIFIER_POINTER (format_type),
"__printf0__")))
{
is_scan = 0;
null_format_ok = 1;
}
else if (TREE_CODE (format_type) == IDENTIFIER_NODE
&& (!strcmp (IDENTIFIER_POINTER (format_type), "scanf")
|| !strcmp (IDENTIFIER_POINTER (format_type),
"__scanf__")))
is_scan = 1;
{
is_scan = 1;
null_format_ok = 0;
}
else
{
error ("unrecognized format specifier for `%s'");
error_with_decl (decl,
"unrecognized format specifier for `%s'");
continue;
}
@ -625,7 +641,8 @@ decl_attributes (node, attributes, prefix_attributes)
record_function_format (DECL_NAME (decl),
DECL_ASSEMBLER_NAME (decl),
is_scan, format_num, first_arg_num);
is_scan, null_format_ok, format_num,
first_arg_num);
break;
}
@ -730,6 +747,7 @@ typedef struct function_format_info {
tree name; /* identifier such as "printf" */
tree assembler_name; /* optional mangled identifier (for C++) */
int is_scan; /* TRUE if *scanf */
int null_format_ok; /* TRUE if the format string may be NULL */
int format_num; /* number of format argument */
int first_arg_num; /* number of first arg (zero for varargs) */
} function_format_info;
@ -748,15 +766,15 @@ static void check_format_info PROTO((function_format_info *, tree));
void
init_function_format_info ()
{
record_function_format (get_identifier ("printf"), NULL_TREE, 0, 1, 2);
record_function_format (get_identifier ("fprintf"), NULL_TREE, 0, 2, 3);
record_function_format (get_identifier ("sprintf"), NULL_TREE, 0, 2, 3);
record_function_format (get_identifier ("scanf"), NULL_TREE, 1, 1, 2);
record_function_format (get_identifier ("fscanf"), NULL_TREE, 1, 2, 3);
record_function_format (get_identifier ("sscanf"), NULL_TREE, 1, 2, 3);
record_function_format (get_identifier ("vprintf"), NULL_TREE, 0, 1, 0);
record_function_format (get_identifier ("vfprintf"), NULL_TREE, 0, 2, 0);
record_function_format (get_identifier ("vsprintf"), NULL_TREE, 0, 2, 0);
record_function_format (get_identifier ("printf"), NULL_TREE, 0, 0, 1, 2);
record_function_format (get_identifier ("fprintf"), NULL_TREE, 0, 0, 2, 3);
record_function_format (get_identifier ("sprintf"), NULL_TREE, 0, 0, 2, 3);
record_function_format (get_identifier ("scanf"), NULL_TREE, 1, 0, 1, 2);
record_function_format (get_identifier ("fscanf"), NULL_TREE, 1, 0, 2, 3);
record_function_format (get_identifier ("sscanf"), NULL_TREE, 1, 0, 2, 3);
record_function_format (get_identifier ("vprintf"), NULL_TREE, 0, 0, 1, 0);
record_function_format (get_identifier ("vfprintf"), NULL_TREE, 0, 0, 2, 0);
record_function_format (get_identifier ("vsprintf"), NULL_TREE, 0, 0, 2, 0);
}
/* Record information for argument format checking. FUNCTION_IDENT is
@ -769,11 +787,12 @@ init_function_format_info ()
(e.g. for varargs such as vfprintf). */
void
record_function_format (name, assembler_name, is_scan,
record_function_format (name, assembler_name, is_scan, null_format_ok,
format_num, first_arg_num)
tree name;
tree assembler_name;
int is_scan;
int null_format_ok;
int format_num;
int first_arg_num;
{
@ -797,6 +816,7 @@ record_function_format (name, assembler_name, is_scan,
}
info->is_scan = is_scan;
info->null_format_ok = null_format_ok;
info->format_num = format_num;
info->first_arg_num = first_arg_num;
}
@ -876,7 +896,8 @@ check_format_info (info, params)
format_tree = TREE_OPERAND (format_tree, 0); /* strip coercion */
if (integer_zerop (format_tree))
{
warning ("null format string");
if (!info->null_format_ok)
warning ("null format string");
return;
}
if (TREE_CODE (format_tree) != ADDR_EXPR)

2
contrib/gcc/c-tree.h
View File

@ -159,7 +159,7 @@ extern void gen_aux_info_record PROTO((tree, int, int, int));
extern void declare_function_name PROTO((void));
extern void decl_attributes PROTO((tree, tree, tree));
extern void init_function_format_info PROTO((void));
extern void record_function_format PROTO((tree, tree, int, int, int));
extern void record_function_format PROTO((tree, tree, int, int, int, int));
extern void check_function_format PROTO((tree, tree, tree));
/* Print an error message for invalid operands to arith operation CODE.
NOP_EXPR is used as a special case (see truthvalue_conversion). */

16
contrib/gcc/extend.texi
View File

@ -1394,13 +1394,15 @@ for consistency with the @code{printf} style format string argument
@code{my_format}.
The parameter @var{archetype} determines how the format string is
interpreted, and should be either @code{printf} or @code{scanf}. The
parameter @var{string-index} specifies which argument is the format
string argument (starting from 1), while @var{first-to-check} is the
number of the first argument to check against the format string. For
functions where the arguments are not available to be checked (such as
@code{vprintf}), specify the third parameter as zero. In this case the
compiler only checks the format string for consistency.
interpreted, and should be @code{printf}, @code{printf0}, or
@code{scanf}. @code{printf0} allows the format string to be a null
pointer, while @code{printf} does not. The parameter @var{string-index}
specifies which argument is the format string argument (starting
from 1), while @var{first-to-check} is the number of the first
argument to check against the format string. For functions where
the arguments are not available to be checked (such as @code{vprintf}),
specify the third parameter as zero. In this case the compiler
only checks the format string for consistency.
In the example above, the format string (@code{my_format}) is the second
argument of the function @code{my_print}, and the arguments to check