X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=format_check.c;h=5d7f0a1dad7a8abde5277fe7d285427977c24aed;hb=76ebc662b0acb3571f519f150fce9eeba3f619f6;hp=870b5d3fb0cbf5da6b7543a47a0438b077fc50fb;hpb=f3f57226195059ecb38d482c469a4c665fc9c2d1;p=cparser

diff --git a/format_check.c b/format_check.c
index 870b5d3..5d7f0a1 100644
--- a/format_check.c
+++ b/format_check.c
@@ -17,16 +17,19 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  * 02111-1307, USA.
  */
+#include <ctype.h>
 #include <wctype.h>
 
+#include "adt/util.h"
 #include "format_check.h"
 #include "symbol_t.h"
 #include "ast_t.h"
+#include "entity_t.h"
 #include "diagnostic.h"
 #include "types.h"
 #include "type_t.h"
 #include "warning.h"
-
+#include "lang_features.h"
 
 typedef enum format_flag_t {
 	FMT_FLAG_NONE  = 0,
@@ -50,9 +53,21 @@ typedef enum format_length_modifier_t {
 	FMT_MOD_j,
 	FMT_MOD_t,
 	FMT_MOD_z,
-	FMT_MOD_q
+	FMT_MOD_q,
+	/* only in microsoft mode */
+	FMT_MOD_w,
+	FMT_MOD_I,
+	FMT_MOD_I32,
+	FMT_MOD_I64
 } format_length_modifier_t;
 
+typedef struct format_spec_t {
+	const char    *name;     /**< name of the function */
+	format_kind_t  fmt_kind; /**< kind */
+	unsigned       fmt_idx;  /**< index of the format string */
+	unsigned       arg_idx;  /**< index of the first argument */
+} format_spec_t;
+
 static const char* get_length_modifier_name(const format_length_modifier_t mod)
 {
 	static const char* const names[] = {
@@ -65,13 +80,18 @@ static const char* get_length_modifier_name(const format_length_modifier_t mod)
 		[FMT_MOD_j]    = "j",
 		[FMT_MOD_t]    = "t",
 		[FMT_MOD_z]    = "z",
-		[FMT_MOD_q]    = "q"
+		[FMT_MOD_q]    = "q",
+		/* only in microsoft mode */
+		[FMT_MOD_w]    = "w",
+		[FMT_MOD_I]    = "I",
+		[FMT_MOD_I32]  = "I32",
+		[FMT_MOD_I64]  = "I64"
 	};
-	assert(mod < sizeof(names) / sizeof(*names));
+	assert(mod < lengthof(names));
 	return names[mod];
 }
 
-static void warn_invalid_length_modifier(const source_position_t pos,
+static void warn_invalid_length_modifier(const source_position_t *pos,
                                          const format_length_modifier_t mod,
                                          const wchar_rep_t conversion)
 {
@@ -81,41 +101,128 @@ static void warn_invalid_length_modifier(const source_position_t pos,
 	);
 }
 
-static void check_format_arguments(const call_argument_t *const fmt_arg, const call_argument_t* arg)
+typedef struct vchar_t vchar_t;
+struct vchar_t {
+	const void *string;   /**< the string */
+	size_t     position;  /**< current position */
+	size_t     size;      /**< size of the string */
+
+	/** return the first character of the string and setthe position to 0. */
+	unsigned (*first)(vchar_t *self);
+	/** return the next character of the string */
+	unsigned (*next)(vchar_t *self);
+	/** return non_zero if the given character is a digit */
+	int (*is_digit)(unsigned vchar);
+};
+
+static unsigned string_first(vchar_t *self)
+{
+	self->position = 0;
+	const string_t *string = self->string;
+	return string->begin[0];
+}
+
+static unsigned string_next(vchar_t *self)
+{
+	++self->position;
+	const string_t *string = self->string;
+	return string->begin[self->position];
+}
+
+static int string_isdigit(unsigned vchar)
+{
+	return isdigit(vchar);
+}
+
+static unsigned wstring_first(vchar_t *self)
+{
+	self->position = 0;
+	const wide_string_t *wstring = self->string;
+	return wstring->begin[0];
+}
+
+static unsigned wstring_next(vchar_t *self)
+{
+	++self->position;
+	const wide_string_t *wstring = self->string;
+	return wstring->begin[self->position];
+}
+
+static int wstring_isdigit(unsigned vchar)
+{
+	return iswdigit(vchar);
+}
+
+static bool atend(vchar_t *self)
 {
-	const expression_t *fmt_expr = fmt_arg->expression;
+	return self->position + 1 == self->size;
+}
+
+/**
+ * Check printf-style format.
+ */
+static void check_printf_format(const call_argument_t *arg, const format_spec_t *spec)
+{
+	/* find format arg */
+	unsigned idx = 0;
+	for (; idx < spec->fmt_idx; ++idx) {
+		if (arg == NULL)
+			return;
+		arg = arg->next;
+	}
+
+	const expression_t *fmt_expr = arg->expression;
 	if (fmt_expr->kind == EXPR_UNARY_CAST_IMPLICIT) {
 		fmt_expr = fmt_expr->unary.value;
 	}
 
-	if (fmt_expr->kind != EXPR_WIDE_STRING_LITERAL)
+	vchar_t vchar;
+	if (fmt_expr->kind == EXPR_WIDE_STRING_LITERAL) {
+		vchar.string   = &fmt_expr->wide_string.value;
+		vchar.size     = fmt_expr->wide_string.value.size;
+		vchar.first    = wstring_first;
+		vchar.next     = wstring_next;
+		vchar.is_digit = wstring_isdigit;
+	} else if (fmt_expr->kind == EXPR_STRING_LITERAL) {
+		vchar.string   = &fmt_expr->string.value;
+		vchar.size     = fmt_expr->string.value.size;
+		vchar.first    = string_first;
+		vchar.next     = string_next;
+		vchar.is_digit = string_isdigit;
+	} else {
 		return;
+	}
+	/* find the real args */
+	for(; idx < spec->arg_idx && arg != NULL; ++idx)
+		arg = arg->next;
 
-	const source_position_t    pos     = fmt_expr->base.source_position;
-	const wide_string_t *const wstring = &fmt_expr->wide_string.value;
-	const wchar_rep_t *fmt = wstring->begin;
-	for (; *fmt != '\0'; ++fmt) {
-		if (*fmt != '%')
+	const source_position_t *pos = &fmt_expr->base.source_position;
+	unsigned fmt     = vchar.first(&vchar);
+	unsigned num_fmt = 0;
+	for (; fmt != '\0'; fmt = vchar.next(&vchar)) {
+		if (fmt != '%')
 			continue;
-		++fmt;
+		fmt = vchar.next(&vchar);
 
-		if (*fmt == '%')
+		if (fmt == '%')
 			continue;
 
+		++num_fmt;
+
 		format_flags_t fmt_flags = FMT_FLAG_NONE;
-		if (*fmt == '0') {
-			++fmt;
+		if (fmt == '0') {
+			fmt = vchar.next(&vchar);
 			fmt_flags |= FMT_FLAG_ZERO;
 		}
 
 		/* argument selector or minimum field width */
-		if (iswdigit(*fmt)) {
+		if (vchar.is_digit(fmt)) {
 			do {
-				++fmt;
-			} while (iswdigit(*fmt));
+				fmt = vchar.next(&vchar);
+			} while (vchar.is_digit(fmt));
 
 			/* digit string was ... */
-			if (*fmt == '$') {
+			if (fmt == '$') {
 				/* ... argument selector */
 				fmt_flags = FMT_FLAG_NONE; /* reset possibly set 0-flag */
 				/* TODO implement */
@@ -126,7 +233,7 @@ static void check_format_arguments(const call_argument_t *const fmt_arg, const c
 			/* flags */
 			for (;;) {
 				format_flags_t flag;
-				switch (*fmt) {
+				switch (fmt) {
 					case '#':  flag = FMT_FLAG_HASH;  break;
 					case '0':  flag = FMT_FLAG_ZERO;  break;
 					case '-':  flag = FMT_FLAG_MINUS; break;
@@ -134,14 +241,14 @@ static void check_format_arguments(const call_argument_t *const fmt_arg, const c
 
 					case ' ':
 						if (fmt_flags & FMT_FLAG_PLUS) {
-							warningf(pos, "' ' is overridden by prior '+' in conversion specification");
+							warningf(pos, "' ' is overridden by prior '+' in conversion specification %u", num_fmt);
 						}
 						flag = FMT_FLAG_SPACE;
 						break;
 
 					case '+':
 						if (fmt_flags & FMT_FLAG_SPACE) {
-							warningf(pos, "'+' overrides prior ' ' in conversion specification");
+							warningf(pos, "'+' overrides prior ' ' in conversion specification %u", num_fmt);
 						}
 						flag = FMT_FLAG_PLUS;
 						break;
@@ -149,59 +256,61 @@ static void check_format_arguments(const call_argument_t *const fmt_arg, const c
 					default: goto break_fmt_flags;
 				}
 				if (fmt_flags & flag) {
-					warningf(pos, "repeated flag '%c' in conversion specification", (char)*fmt);
+					warningf(pos, "repeated flag '%c' in conversion specification %u", (char)fmt, num_fmt);
 				}
 				fmt_flags |= flag;
-				++fmt;
+				fmt = vchar.next(&vchar);
 			}
 break_fmt_flags:
 
 			/* minimum field width */
-			if (*fmt == '*') {
+			if (fmt == '*') {
+				fmt = vchar.next(&vchar);
 				if (arg == NULL) {
-					warningf(pos, "missing argument for '*' field width in conversion specification");
+					warningf(pos, "missing argument for '*' field width in conversion specification %u", num_fmt);
 					return;
 				}
 				const type_t *const arg_type = arg->expression->base.type;
 				if (arg_type != type_int) {
-					warningf(pos, "argument for '*' field width in conversion specification is not an 'int', but an '%T'", arg_type);
+					warningf(pos, "argument for '*' field width in conversion specification %u is not an 'int', but an '%T'", num_fmt, arg_type);
 				}
 				arg = arg->next;
 			} else {
-				while (iswdigit(*fmt)) {
-					++fmt;
+				while (vchar.is_digit(fmt)) {
+					fmt = vchar.next(&vchar);
 				}
 			}
 		}
 
 		/* precision */
-		if (*fmt == '.') {
-			++fmt;
-			if (*fmt == '*') {
+		if (fmt == '.') {
+			fmt = vchar.next(&vchar);
+			if (fmt == '*') {
+				fmt = vchar.next(&vchar);
 				if (arg == NULL) {
-					warningf(pos, "missing argument for '*' precision in conversion specification");
+					warningf(pos, "missing argument for '*' precision in conversion specification %u", num_fmt);
 					return;
 				}
 				const type_t *const arg_type = arg->expression->base.type;
 				if (arg_type != type_int) {
-					warningf(pos, "argument for '*' precision in conversion specification is not an 'int', but an '%T'", arg_type);
+					warningf(pos, "argument for '*' precision in conversion specification %u is not an 'int', but an '%T'", num_fmt, arg_type);
 				}
 				arg = arg->next;
 			} else {
 				/* digit string may be omitted */
-				while (iswdigit(*fmt)) {
-					++fmt;
+				while (vchar.is_digit(fmt)) {
+					fmt = vchar.next(&vchar);
 				}
 			}
 		}
 
 		/* length modifier */
 		format_length_modifier_t fmt_mod;
-		switch (*fmt) {
+		switch (fmt) {
 			case 'h':
-				++fmt;
-				if (*fmt == 'h') {
-					++fmt;
+				fmt = vchar.next(&vchar);
+				if (fmt == 'h') {
+					fmt = vchar.next(&vchar);
 					fmt_mod = FMT_MOD_hh;
 				} else {
 					fmt_mod = FMT_MOD_h;
@@ -209,32 +318,68 @@ break_fmt_flags:
 				break;
 
 			case 'l':
-				++fmt;
-				if (*fmt == 'l') {
-					++fmt;
+				fmt = vchar.next(&vchar);
+				if (fmt == 'l') {
+					fmt = vchar.next(&vchar);
 					fmt_mod = FMT_MOD_ll;
 				} else {
 					fmt_mod = FMT_MOD_l;
 				}
 				break;
 
-			case 'L': ++fmt; fmt_mod = FMT_MOD_L;    break;
-			case 'j': ++fmt; fmt_mod = FMT_MOD_j;    break;
-			case 't': ++fmt; fmt_mod = FMT_MOD_t;    break;
-			case 'z': ++fmt; fmt_mod = FMT_MOD_z;    break;
-			case 'q': ++fmt; fmt_mod = FMT_MOD_q;    break;
-			default:         fmt_mod = FMT_MOD_NONE; break;
+			case 'L': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_L;    break;
+			case 'j': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_j;    break;
+			case 't': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_t;    break;
+			case 'z': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_z;    break;
+			case 'q': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_q;    break;
+			/* microsoft mode */
+			case 'w':
+				if (c_mode & _MS) {
+					fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_w;
+				} else {
+					fmt_mod = FMT_MOD_NONE;
+				}
+				break;
+			case 'I':
+				if (c_mode & _MS) {
+					fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_I;
+					if (fmt == '3') {
+						fmt = vchar.next(&vchar);
+						if (fmt == '2') {
+							fmt = vchar.next(&vchar);
+							fmt_mod = FMT_MOD_I32;
+						} else {
+							/* rewind */
+							--vchar.position;
+						}
+					} else if (fmt == '6') {
+						fmt = vchar.next(&vchar);
+						if (fmt == '4') {
+							fmt = vchar.next(&vchar);
+							fmt_mod = FMT_MOD_I64;
+						} else {
+							/* rewind */
+							--vchar.position;
+						}
+					}
+				} else {
+					fmt_mod = FMT_MOD_NONE;
+				}
+				break;
+			default:
+				fmt_mod = FMT_MOD_NONE;
+				break;
 		}
 
-		if (*fmt == '\0') {
+		if (fmt == '\0') {
 			warningf(pos, "dangling %% in format string");
 			break;
 		}
 
-		const type_t      *expected_type;
+		type_t            *expected_type;
 		type_qualifiers_t  expected_qual = TYPE_QUALIFIER_NONE;
 		format_flags_t     allowed_flags;
-		switch (*fmt) {
+		switch (fmt) {
 			case 'd':
 			case 'i':
 				switch (fmt_mod) {
@@ -246,9 +391,12 @@ break_fmt_flags:
 					case FMT_MOD_j:    expected_type = type_intmax_t;  break;
 					case FMT_MOD_z:    expected_type = type_ssize_t;   break;
 					case FMT_MOD_t:    expected_type = type_ptrdiff_t; break;
+					case FMT_MOD_I:    expected_type = type_ptrdiff_t; break;
+					case FMT_MOD_I32:  expected_type = type_int32;     break;
+					case FMT_MOD_I64:  expected_type = type_int64;     break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				allowed_flags = FMT_FLAG_MINUS | FMT_FLAG_SPACE | FMT_FLAG_PLUS | FMT_FLAG_ZERO;
@@ -259,7 +407,6 @@ break_fmt_flags:
 			case 'x':
 				allowed_flags = FMT_FLAG_MINUS | FMT_FLAG_HASH | FMT_FLAG_ZERO;
 				goto eval_fmt_mod_unsigned;
-				break;
 
 			case 'u':
 				allowed_flags = FMT_FLAG_MINUS | FMT_FLAG_ZERO;
@@ -273,9 +420,12 @@ eval_fmt_mod_unsigned:
 					case FMT_MOD_j:    expected_type = type_uintmax_t;          break;
 					case FMT_MOD_z:    expected_type = type_size_t;             break;
 					case FMT_MOD_t:    expected_type = type_uptrdiff_t;         break;
+					case FMT_MOD_I:    expected_type = type_size_t;             break;
+					case FMT_MOD_I32:  expected_type = type_unsigned_int32;     break;
+					case FMT_MOD_I64:  expected_type = type_unsigned_int64;     break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				break;
@@ -294,7 +444,7 @@ eval_fmt_mod_unsigned:
 					case FMT_MOD_L:    expected_type = type_long_double; break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				allowed_flags = FMT_FLAG_MINUS | FMT_FLAG_SPACE | FMT_FLAG_PLUS | FMT_FLAG_HASH | FMT_FLAG_ZERO;
@@ -302,7 +452,7 @@ eval_fmt_mod_unsigned:
 
 			case 'C':
 				if (fmt_mod != FMT_MOD_NONE) {
-					warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
 					goto next_arg;
 				}
 				expected_type = type_wchar_t;
@@ -312,11 +462,12 @@ eval_fmt_mod_unsigned:
 			case 'c':
 				expected_type = type_int;
 				switch (fmt_mod) {
-					case FMT_MOD_NONE: expected_type = type_int;    break; /* TODO promoted char */
-					case FMT_MOD_l:    expected_type = type_wint_t; break;
+					case FMT_MOD_NONE: expected_type = type_int;     break; /* TODO promoted char */
+					case FMT_MOD_l:    expected_type = type_wint_t;  break;
+					case FMT_MOD_w:    expected_type = type_wchar_t; break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				allowed_flags = FMT_FLAG_NONE;
@@ -324,30 +475,31 @@ eval_fmt_mod_unsigned:
 
 			case 'S':
 				if (fmt_mod != FMT_MOD_NONE) {
-					warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
 					goto next_arg;
 				}
 				expected_type = type_wchar_t_ptr;
 				expected_qual = TYPE_QUALIFIER_CONST;
-				allowed_flags = FMT_FLAG_NONE;
+				allowed_flags = FMT_FLAG_MINUS;
 				break;
 
 			case 's':
 				switch (fmt_mod) {
 					case FMT_MOD_NONE: expected_type = type_char_ptr;    break;
 					case FMT_MOD_l:    expected_type = type_wchar_t_ptr; break;
+					case FMT_MOD_w:    expected_type = type_wchar_t_ptr; break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				expected_qual = TYPE_QUALIFIER_CONST;
-				allowed_flags = FMT_FLAG_NONE;
+				allowed_flags = FMT_FLAG_MINUS;
 				break;
 
 			case 'p':
 				if (fmt_mod != FMT_MOD_NONE) {
-					warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
 					goto next_arg;
 				}
 				expected_type = type_void_ptr;
@@ -366,20 +518,34 @@ eval_fmt_mod_unsigned:
 					case FMT_MOD_t:    expected_type = type_ptrdiff_t_ptr;   break;
 
 					default:
-						warn_invalid_length_modifier(pos, fmt_mod, *fmt);
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
 						goto next_arg;
 				}
 				allowed_flags = FMT_FLAG_NONE;
 				break;
 
 			default:
-				warningf(pos, "encountered unknown conversion specifier '%%%C'", (wint_t)*fmt);
+				warningf(pos, "encountered unknown conversion specifier '%%%C' at position %u", (wint_t)fmt, num_fmt);
+				if (arg == NULL) {
+					warningf(pos, "too few arguments for format string");
+					return;
+				}
 				goto next_arg;
 		}
 
-		if ((fmt_flags & ~allowed_flags) != 0) {
-			/* TODO better warning message text */
-			warningf(pos, "invalid format flags in conversion specification");
+		format_flags_t wrong_flags = fmt_flags & ~allowed_flags;
+		if (wrong_flags != 0) {
+			char  wrong[8];
+			char *p = wrong;
+			if (wrong_flags & FMT_FLAG_HASH)  *p++ = '#';
+			if (wrong_flags & FMT_FLAG_ZERO)  *p++ = '0';
+			if (wrong_flags & FMT_FLAG_MINUS) *p++ = '-';
+			if (wrong_flags & FMT_FLAG_SPACE) *p++ = ' ';
+			if (wrong_flags & FMT_FLAG_PLUS)  *p++ = '+';
+			if (wrong_flags & FMT_FLAG_TICK)  *p++ = '\'';
+			*p = '\0';
+
+			warningf(pos, "invalid format flags \"%s\" in conversion specification %%%c at position %u", wrong, fmt, num_fmt);
 		}
 
 		if (arg == NULL) {
@@ -388,11 +554,19 @@ eval_fmt_mod_unsigned:
 		}
 
 		{	/* create a scope here to prevent warning about the jump to next_arg */
-			type_t *const arg_type = arg->expression->base.type;
-			if (is_type_pointer(expected_type)) {
-				type_t *const arg_skip = skip_typeref(arg_type);
+			type_t *const arg_type           = arg->expression->base.type;
+			type_t *const arg_skip           = skip_typeref(arg_type);
+			type_t *const expected_type_skip = skip_typeref(expected_type);
+
+			if (fmt == 'p') {
+				/* allow any pointer type for %p, not just void */
+				if (is_type_pointer(arg_skip))
+					goto next_arg;
+			}
+
+			if (is_type_pointer(expected_type_skip)) {
 				if (is_type_pointer(arg_skip)) {
-					type_t *const exp_to = skip_typeref(expected_type->pointer.points_to);
+					type_t *const exp_to = skip_typeref(expected_type_skip->pointer.points_to);
 					type_t *const arg_to = skip_typeref(arg_skip->pointer.points_to);
 					if ((arg_to->base.qualifiers & ~expected_qual) == 0 &&
 						get_unqualified_type(arg_to) == exp_to) {
@@ -400,42 +574,441 @@ eval_fmt_mod_unsigned:
 					}
 				}
 			} else {
-				if (get_unqualified_type(skip_typeref(arg_type)) == expected_type) {
+				if (get_unqualified_type(arg_skip) == expected_type_skip) {
+					goto next_arg;
+				}
+			}
+			if (is_type_valid(arg_skip)) {
+				warningf(pos,
+					"argument type '%T' does not match conversion specifier '%%%s%c' at position %u",
+					arg_type, get_length_modifier_name(fmt_mod), (char)fmt, num_fmt);
+			}
+		}
+next_arg:
+		arg = arg->next;
+	}
+	if (!atend(&vchar)) {
+		warningf(pos, "format string contains '\\0'");
+	}
+	if (arg != NULL) {
+		unsigned num_args = num_fmt;
+		while (arg != NULL) {
+			++num_args;
+			arg = arg->next;
+		}
+		warningf(pos, "%u argument%s but only %u format specifier%s",
+			num_args, num_args != 1 ? "s" : "",
+			num_fmt, num_fmt != 1 ? "s" : "");
+	}
+}
+
+/**
+ * Check scanf-style format.
+ */
+static void check_scanf_format(const call_argument_t *arg, const format_spec_t *spec)
+{
+	/* find format arg */
+	unsigned idx = 0;
+	for (; idx < spec->fmt_idx; ++idx) {
+		if (arg == NULL)
+			return;
+		arg = arg->next;
+	}
+
+	const expression_t *fmt_expr = arg->expression;
+	if (fmt_expr->kind == EXPR_UNARY_CAST_IMPLICIT) {
+		fmt_expr = fmt_expr->unary.value;
+	}
+
+	vchar_t vchar;
+	if (fmt_expr->kind == EXPR_WIDE_STRING_LITERAL) {
+		vchar.string   = &fmt_expr->wide_string.value;
+		vchar.size     = fmt_expr->wide_string.value.size;
+		vchar.first    = wstring_first;
+		vchar.next     = wstring_next;
+		vchar.is_digit = wstring_isdigit;
+	} else if (fmt_expr->kind == EXPR_STRING_LITERAL) {
+		vchar.string   = &fmt_expr->string.value;
+		vchar.size     = fmt_expr->string.value.size;
+		vchar.first    = string_first;
+		vchar.next     = string_next;
+		vchar.is_digit = string_isdigit;
+	} else {
+		return;
+	}
+	/* find the real args */
+	for (; idx < spec->arg_idx && arg != NULL; ++idx)
+		arg = arg->next;
+
+	const source_position_t *pos = &fmt_expr->base.source_position;
+	unsigned fmt     = vchar.first(&vchar);
+	unsigned num_fmt = 0;
+	for (; fmt != '\0'; fmt = vchar.next(&vchar)) {
+		if (fmt != '%')
+			continue;
+		fmt = vchar.next(&vchar);
+
+		if (fmt == '%')
+			continue;
+
+		++num_fmt;
+
+		/* length modifier */
+		format_length_modifier_t fmt_mod;
+		switch (fmt) {
+			case 'h':
+				fmt = vchar.next(&vchar);
+				if (fmt == 'h') {
+					fmt = vchar.next(&vchar);
+					fmt_mod = FMT_MOD_hh;
+				} else {
+					fmt_mod = FMT_MOD_h;
+				}
+				break;
+
+			case 'l':
+				fmt = vchar.next(&vchar);
+				if (fmt == 'l') {
+					fmt = vchar.next(&vchar);
+					fmt_mod = FMT_MOD_ll;
+				} else {
+					fmt_mod = FMT_MOD_l;
+				}
+				break;
+
+			case 'L': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_L;    break;
+			case 'j': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_j;    break;
+			case 't': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_t;    break;
+			case 'z': fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_z;    break;
+			/* microsoft mode */
+			case 'w':
+				if (c_mode & _MS) {
+					fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_w;
+				} else {
+					fmt_mod = FMT_MOD_NONE;
+				}
+				break;
+			case 'I':
+				if (c_mode & _MS) {
+					fmt = vchar.next(&vchar); fmt_mod = FMT_MOD_I;
+					if (fmt == '3') {
+						fmt = vchar.next(&vchar);
+						if (fmt == '2') {
+							fmt = vchar.next(&vchar);
+							fmt_mod = FMT_MOD_I32;
+						} else {
+							/* rewind */
+							--vchar.position;
+						}
+					} else if (fmt == '6') {
+						fmt = vchar.next(&vchar);
+						if (fmt == '4') {
+							fmt = vchar.next(&vchar);
+							fmt_mod = FMT_MOD_I64;
+						} else {
+							/* rewind */
+							--vchar.position;
+						}
+					}
+				} else {
+					fmt_mod = FMT_MOD_NONE;
+				}
+				break;
+			default:
+				fmt_mod = FMT_MOD_NONE;
+				break;
+		}
+
+		if (fmt == '\0') {
+			warningf(pos, "dangling %% in format string");
+			break;
+		}
+
+		type_t            *expected_type;
+		switch (fmt) {
+			case 'd':
+			case 'i':
+				switch (fmt_mod) {
+					case FMT_MOD_NONE: expected_type = type_int;         break;
+					case FMT_MOD_hh:   expected_type = type_signed_char; break;
+					case FMT_MOD_h:    expected_type = type_short;       break;
+					case FMT_MOD_l:    expected_type = type_long;        break;
+					case FMT_MOD_ll:   expected_type = type_long_long;   break;
+					case FMT_MOD_j:    expected_type = type_intmax_t;    break;
+					case FMT_MOD_z:    expected_type = type_ssize_t;     break;
+					case FMT_MOD_t:    expected_type = type_ptrdiff_t;   break;
+					case FMT_MOD_I:    expected_type = type_ptrdiff_t;   break;
+					case FMT_MOD_I32:  expected_type = type_int32;       break;
+					case FMT_MOD_I64:  expected_type = type_int64;       break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			case 'o':
+			case 'X':
+			case 'x':
+				goto eval_fmt_mod_unsigned;
+
+			case 'u':
+eval_fmt_mod_unsigned:
+				switch (fmt_mod) {
+					case FMT_MOD_NONE: expected_type = type_unsigned_int;       break;
+					case FMT_MOD_hh:   expected_type = type_unsigned_char;      break;
+					case FMT_MOD_h:    expected_type = type_unsigned_short;     break;
+					case FMT_MOD_l:    expected_type = type_unsigned_long;      break;
+					case FMT_MOD_ll:   expected_type = type_unsigned_long_long; break;
+					case FMT_MOD_j:    expected_type = type_uintmax_t;          break;
+					case FMT_MOD_z:    expected_type = type_size_t;             break;
+					case FMT_MOD_t:    expected_type = type_uptrdiff_t;         break;
+					case FMT_MOD_I:    expected_type = type_size_t;             break;
+					case FMT_MOD_I32:  expected_type = type_unsigned_int32;     break;
+					case FMT_MOD_I64:  expected_type = type_unsigned_int64;     break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			case 'A':
+			case 'a':
+			case 'E':
+			case 'e':
+			case 'F':
+			case 'f':
+			case 'G':
+			case 'g':
+				switch (fmt_mod) {
+					case FMT_MOD_l:    /* l modifier is ignored */
+					case FMT_MOD_NONE: expected_type = type_double;      break;
+					case FMT_MOD_L:    expected_type = type_long_double; break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			case 'C':
+				if (fmt_mod != FMT_MOD_NONE) {
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
+					goto next_arg;
+				}
+				expected_type = type_wchar_t;
+				break;
+
+			case 'c':
+				expected_type = type_int;
+				switch (fmt_mod) {
+					case FMT_MOD_NONE: expected_type = type_int;     break; /* TODO promoted char */
+					case FMT_MOD_l:    expected_type = type_wint_t;  break;
+					case FMT_MOD_w:    expected_type = type_wchar_t; break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			case 'S':
+				if (fmt_mod != FMT_MOD_NONE) {
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
+					goto next_arg;
+				}
+				expected_type = type_wchar_t;
+				break;
+
+			case 's':
+			case '[':
+				switch (fmt_mod) {
+					case FMT_MOD_NONE: expected_type = type_char;    break;
+					case FMT_MOD_l:    expected_type = type_wchar_t; break;
+					case FMT_MOD_w:    expected_type = type_wchar_t; break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			case 'p':
+				if (fmt_mod != FMT_MOD_NONE) {
+					warn_invalid_length_modifier(pos, fmt_mod, fmt);
 					goto next_arg;
 				}
+				expected_type = type_void_ptr;
+				break;
+
+			case 'n':
+				switch (fmt_mod) {
+					case FMT_MOD_NONE: expected_type = type_int;         break;
+					case FMT_MOD_hh:   expected_type = type_signed_char; break;
+					case FMT_MOD_h:    expected_type = type_short;       break;
+					case FMT_MOD_l:    expected_type = type_long;        break;
+					case FMT_MOD_ll:   expected_type = type_long_long;   break;
+					case FMT_MOD_j:    expected_type = type_intmax_t;    break;
+					case FMT_MOD_z:    expected_type = type_ssize_t;     break;
+					case FMT_MOD_t:    expected_type = type_ptrdiff_t;   break;
+
+					default:
+						warn_invalid_length_modifier(pos, fmt_mod, fmt);
+						goto next_arg;
+				}
+				break;
+
+			default:
+				warningf(pos, "encountered unknown conversion specifier '%%%C' at position %u", (wint_t)fmt, num_fmt);
+				if (arg == NULL) {
+					warningf(pos, "too few arguments for format string");
+					return;
+				}
+				goto next_arg;
+		}
+
+		if (arg == NULL) {
+			warningf(pos, "too few arguments for format string");
+			return;
+		}
+
+		{	/* create a scope here to prevent warning about the jump to next_arg */
+			type_t *const arg_type           = arg->expression->base.type;
+			type_t *const arg_skip           = skip_typeref(arg_type);
+			type_t *const expected_type_skip = skip_typeref(expected_type);
+
+			if (! is_type_pointer(arg_skip))
+				goto error_arg_type;
+			type_t *const ptr_skip = skip_typeref(arg_skip->pointer.points_to);
+
+			if (fmt == 'p') {
+				/* allow any pointer type for %p, not just void */
+				if (is_type_pointer(ptr_skip))
+					goto next_arg;
+			}
+
+			/* do NOT allow const or restrict, all other should be ok */
+			if (ptr_skip->base.qualifiers & (TYPE_QUALIFIER_CONST | TYPE_QUALIFIER_VOLATILE))
+				goto error_arg_type;
+			type_t *const unqual_ptr = get_unqualified_type(ptr_skip);
+			if (unqual_ptr == expected_type_skip) {
+				goto next_arg;
+			} else if (expected_type_skip == type_char) {
+				/* char matches with unsigned char AND signed char */
+				if (unqual_ptr == type_signed_char || unqual_ptr == type_unsigned_char)
+					goto next_arg;
 			}
-			if (is_type_valid(arg_type)) {
+error_arg_type:
+			if (is_type_valid(arg_skip)) {
 				warningf(pos,
-					"argument type '%T' does not match conversion specifier '%%%s%c'",
-					arg_type, get_length_modifier_name(fmt_mod), (char)*fmt);
+					"argument type '%T' does not match conversion specifier '%%%s%c' at position %u",
+					arg_type, get_length_modifier_name(fmt_mod), (char)fmt, num_fmt);
 			}
 		}
 next_arg:
 		arg = arg->next;
 	}
-	if (fmt + 1 != wstring->begin + wstring->size) {
-		warningf(pos, "format string contains NUL");
+	if (!atend(&vchar)) {
+		warningf(pos, "format string contains '\\0'");
 	}
 	if (arg != NULL) {
-		warningf(pos, "too many arguments for format string");
+		unsigned num_args = num_fmt;
+		while (arg != NULL) {
+			++num_args;
+			arg = arg->next;
+		}
+		warningf(pos, "%u argument%s but only %u format specifier%s",
+			num_args, num_args != 1 ? "s" : "",
+			num_fmt, num_fmt != 1 ? "s" : "");
 	}
 }
 
+static const format_spec_t builtin_table[] = {
+	{ "printf",        FORMAT_PRINTF,   0, 1 },
+	{ "wprintf",       FORMAT_PRINTF,   0, 1 },
+	{ "sprintf",       FORMAT_PRINTF,   1, 2 },
+	{ "swprintf",      FORMAT_PRINTF,   1, 2 },
+	{ "snprintf",      FORMAT_PRINTF,   2, 3 },
+	{ "snwprintf",     FORMAT_PRINTF,   2, 3 },
+	{ "fprintf",       FORMAT_PRINTF,   1, 2 },
+	{ "fwprintf",      FORMAT_PRINTF,   1, 2 },
+	{ "snwprintf",     FORMAT_PRINTF,   2, 3 },
+	{ "snwprintf",     FORMAT_PRINTF,   2, 3 },
+
+	{ "scanf",         FORMAT_SCANF,    0, 1 },
+	{ "wscanf",        FORMAT_SCANF,    0, 1 },
+	{ "sscanf",        FORMAT_SCANF,    1, 2 },
+	{ "swscanf",       FORMAT_SCANF,    1, 2 },
+	{ "fscanf",        FORMAT_SCANF,    1, 2 },
+	{ "fwscanf",       FORMAT_SCANF,    1, 2 },
+
+	{ "strftime",      FORMAT_STRFTIME, 3, 4 },
+	{ "wcstrftime",    FORMAT_STRFTIME, 3, 4 },
+
+	{ "strfmon",       FORMAT_STRFMON,  3, 4 },
+
+	/* MS extensions */
+	{ "_snprintf",     FORMAT_PRINTF,   2, 3 },
+	{ "_snwprintf",    FORMAT_PRINTF,   2, 3 },
+	{ "_scrintf",      FORMAT_PRINTF,   0, 1 },
+	{ "_scwprintf",    FORMAT_PRINTF,   0, 1 },
+	{ "printf_s",      FORMAT_PRINTF,   0, 1 },
+	{ "wprintf_s",     FORMAT_PRINTF,   0, 1 },
+	{ "sprintf_s",     FORMAT_PRINTF,   3, 4 },
+	{ "swprintf_s",    FORMAT_PRINTF,   3, 4 },
+	{ "fprintf_s",     FORMAT_PRINTF,   1, 2 },
+	{ "fwprintf_s",    FORMAT_PRINTF,   1, 2 },
+	{ "_sprintf_l",    FORMAT_PRINTF,   1, 3 },
+	{ "_swprintf_l",   FORMAT_PRINTF,   1, 3 },
+	{ "_printf_l",     FORMAT_PRINTF,   0, 2 },
+	{ "_wprintf_l",    FORMAT_PRINTF,   0, 2 },
+	{ "_fprintf_l",    FORMAT_PRINTF,   1, 3 },
+	{ "_fwprintf_l",   FORMAT_PRINTF,   1, 3 },
+	{ "_printf_s_l",   FORMAT_PRINTF,   0, 2 },
+	{ "_wprintf_s_l",  FORMAT_PRINTF,   0, 2 },
+	{ "_sprintf_s_l",  FORMAT_PRINTF,   3, 5 },
+	{ "_swprintf_s_l", FORMAT_PRINTF,   3, 5 },
+	{ "_fprintf_s_l",  FORMAT_PRINTF,   1, 3 },
+	{ "_fwprintf_s_l", FORMAT_PRINTF,   1, 3 },
+};
+
 void check_format(const call_expression_t *const call)
 {
-	if (!warning.check_format)
+	if (!warning.format)
 		return;
 
 	const expression_t *const func_expr = call->function;
 	if (func_expr->kind != EXPR_REFERENCE)
 		return;
 
-	const char            *const name = func_expr->reference.symbol->string;
-	const call_argument_t *      arg  = call->arguments;
-	if (strcmp(name, "wprintf") == 0) { /* TODO gammlig */
-		check_format_arguments(arg, arg->next);
-	} else if (strcmp(name, "swprintf") == 0) {
-		arg = arg->next->next; /* skip destination buffer and size */
-		check_format_arguments(arg, arg->next);
+	const entity_t        *const entity = func_expr->reference.entity;
+	const call_argument_t *      arg    = call->arguments;
+
+	if (false) {
+		/* the declaration has a GNU format attribute, check it */
+	} else {
+		/*
+		 * For some functions we always check the format, even if it was not specified.
+		 * This allows to check format even in MS mode or without header included.
+		 */
+		const char *const name = entity->base.symbol->string;
+		for (size_t i = 0; i < lengthof(builtin_table); ++i) {
+			if (strcmp(name, builtin_table[i].name) == 0) {
+				switch (builtin_table[i].fmt_kind) {
+				case FORMAT_PRINTF:
+					check_printf_format(arg, &builtin_table[i]);
+					break;
+				case FORMAT_SCANF:
+					check_scanf_format(arg, &builtin_table[i]);
+					break;
+				case FORMAT_STRFTIME:
+				case FORMAT_STRFMON:
+					/* TODO: implement other cases */
+					break;
+				}
+				break;
+			}
+		}
 	}
 }