add support for -Wmemcpy-max-count

sparse will warn if memcpy() (or memset(), copy_from_user(),
copy_to_user()) is called with a very large static byte-count.

But this warning is given unconditionaly while there are projects
where this warning may not be not desired.

Change this by making this warning conditional on a new warning
flag: -W[no-]memcpy-max-count

Signed-off-by: Luc Van Oostenryck <[email protected]>

Author: lucvoo

cgcc

@@ -101,7 +101,7 @@ exit 0;
 
 sub check_only_option {
     my ($arg) = @_;
-    return 1 if $arg =~ /^-W(no-?)?(address-space|bitwise|cast-to-as|cast-truncate|context|decl|default-bitfield-sign|designated-init|do-while|enum-mismatch|init-cstring|non-pointer-null|old-initializer|one-bit-signed-bitfield|override-init-all|paren-string|ptr-subtraction-blows|return-void|sizeof-bool|sparse-all|sparse-error|transparent-union|typesign|undef|unknown-attribute)$/;
+    return 1 if $arg =~ /^-W(no-?)?(address-space|bitwise|cast-to-as|cast-truncate|context|decl|default-bitfield-sign|designated-init|do-while|enum-mismatch|init-cstring|memcpy-max-count|non-pointer-null|old-initializer|one-bit-signed-bitfield|override-init-all|paren-string|ptr-subtraction-blows|return-void|sizeof-bool|sparse-all|sparse-error|transparent-union|typesign|undef|unknown-attribute)$/;
     return 1 if $arg =~ /^-v(no-?)?(entry|dead)$/;
     return 1 if $arg =~ /^-f(dump-linearize)(=\S*)?$/;
     return 0;

lib.c

@@ -230,6 +230,7 @@ int Wdo_while = 0;
 int Winit_cstring = 0;
 int Wenum_mismatch = 1;
 int Wsparse_error = 0;
+int Wmemcpy_max_count = 1;
 int Wnon_pointer_null = 1;
 int Wold_initializer = 1;
 int Wone_bit_signed_bitfield = 1;
@@ -506,6 +507,7 @@ static const struct warning {
 	{ "do-while", &Wdo_while },
 	{ "enum-mismatch", &Wenum_mismatch },
 	{ "init-cstring", &Winit_cstring },
+	{ "memcpy-max-count", &Wmemcpy_max_count },
 	{ "non-pointer-null", &Wnon_pointer_null },
 	{ "old-initializer", &Wold_initializer },
 	{ "one-bit-signed-bitfield", &Wone_bit_signed_bitfield },

lib.h

@@ -120,6 +120,7 @@ extern int Wdo_while;
 extern int Wenum_mismatch;
 extern int Wsparse_error;
 extern int Winit_cstring;
+extern int Wmemcpy_max_count;
 extern int Wnon_pointer_null;
 extern int Wold_initializer;
 extern int Wone_bit_signed_bitfield;

sparse.1

@@ -210,6 +210,14 @@ trouble.
 Sparse does not issue these warnings by default.
 .
 .TP
+.B \-Wmemcpy\-max\-count
+Warn about call of \fBmemcpy()\fR, \fBmemset()\fR, \fBcopy_from_user()\fR, or
+\fBcopy_to_user()\fR with a large compile-time byte count.
+
+Sparse issues these warnings by default. To turn them off, use
+\fB\-Wno\-memcpy\-max\-count\fR.
+.
+.TP
 .B \-Wnon\-pointer\-null
 Warn about the use of 0 as a NULL pointer.
 

sparse.c

@@ -153,7 +153,8 @@ static void check_byte_count(struct instruction *insn, pseudo_t count)
 		return;
 	if (count->type == PSEUDO_VAL) {
 		unsigned long long val = count->value;
-		if (val > 100000ULL)
+		if (Wmemcpy_max_count && val > 100000ULL)
+
 			warning(insn->pos, "%s with byte count of %llu",
 				show_ident(insn->func->sym->ident), val);
 		return;