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BR 3392906: error out on bad syntax "db 1 2"

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NASM would try to "eat the comma token" in db expressions, even for
cases where the token was not a comma. Fix that and error out
properly.

To give better error messages, track where in the input string a token
starts or ends. This information is only valid as long as the input
string is kept, but that is just fine for error messages during
parsing.

Reported-by: Peter Cordes <pcordes@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2023-10-11 12:01:22 -07:00
parent 816f50e5f5
commit 73676357de
5 changed files with 76 additions and 27 deletions
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60
asm/parser.c
View File

@ -1,6 +1,6 @@
/* ----------------------------------------------------------------------- *
*
* Copyright 1996-2020 The NASM Authors - All Rights Reserved
* Copyright 1996-2023 The NASM Authors - All Rights Reserved
* See the file AUTHORS included with the NASM distribution for
* the specific copyright holders.
*
@ -55,6 +55,21 @@ static int end_expression_next(void);
static struct tokenval tokval;
/*
* Human-readable description of a token, intended for error messages.
* The resulting string needs to be freed.
*/
static char *tokstr(const struct tokenval *tok)
{
if (tok->t_type == TOKEN_EOS) {
return nasm_strdup("end of line");
} else if (tok->t_len) {
return nasm_asprintf("`%.*s'", tok->t_len, tok->t_start);
} else {
return nasm_strdup("invalid token");
}
}
static void process_size_override(insn *result, operand *op)
{
if (tasm_compatible_mode) {
@ -384,6 +399,7 @@ static int parse_eops(extop **result, bool critical, int elem)
/* End of string is obvious; ) ends a sub-expression list e.g. DUP */
for (i = tokval.t_type; i != TOKEN_EOS; i = stdscan(NULL, &tokval)) {
bool skip;
char endparen = ')'; /* Is a right paren the end of list? */
if (i == ')')
@ -397,12 +413,9 @@ static int parse_eops(extop **result, bool critical, int elem)
}
sign = +1;
/*
* end_expression_next() here is to distinguish this from
* a string used as part of an expression...
*/
if (i == TOKEN_QMARK) {
eop->type = EOT_DB_RESERVE;
skip = true;
} else if (do_subexpr && i == '(') {
extop *subexpr;
@ -432,12 +445,13 @@ static int parse_eops(extop **result, bool critical, int elem)
/* We should have ended on a closing paren */
if (tokval.t_type != ')') {
nasm_nonfatal("expected `)' after subexpression, got `%s'",
i == TOKEN_EOS ?
"end of line" : tokval.t_charptr);
char *tp = tokstr(&tokval);
nasm_nonfatal("expected `)' after subexpression, got %s", tp);
nasm_free(tp);
goto fail;
}
endparen = 0; /* This time the paren is not the end */
skip = true;
} else if (i == '%') {
/* %(expression_list) */
do_subexpr = true;
@ -448,9 +462,14 @@ static int parse_eops(extop **result, bool critical, int elem)
do_subexpr = true;
continue;
} else if (i == TOKEN_STR && end_expression_next()) {
/*
* end_expression_next() is to distinguish this from
* a string used as part of an expression...
*/
eop->type = EOT_DB_STRING;
eop->val.string.data = tokval.t_charptr;
eop->val.string.len = tokval.t_inttwo;
skip = true;
} else if (i == TOKEN_STRFUNC) {
bool parens = false;
const char *funcname = tokval.t_charptr;
@ -463,8 +482,10 @@ static int parse_eops(extop **result, bool critical, int elem)
i = stdscan(NULL, &tokval);
}
if (i != TOKEN_STR) {
nasm_nonfatal("%s must be followed by a string constant",
funcname);
char *tp = tokstr(&tokval);
nasm_nonfatal("%s must be followed by a string constant, got %s",
funcname, tp);
nasm_free(tp);
eop->type = EOT_NOTHING;
} else {
eop->type = EOT_DB_STRING_FREE;
@ -481,6 +502,7 @@ static int parse_eops(extop **result, bool critical, int elem)
if (i != ')')
nasm_nonfatal("unterminated %s function", funcname);
}
skip = i != ',';
} else if (i == '-' || i == '+') {
char *save = stdscan_get();
struct tokenval tmptok;
@ -522,6 +544,7 @@ static int parse_eops(extop **result, bool critical, int elem)
}
if (!eop->val.string.len)
eop->type = EOT_NOTHING;
skip = true;
} else {
/* anything else, assume it is an expression */
expr *value;
@ -548,6 +571,7 @@ static int parse_eops(extop **result, bool critical, int elem)
if (value_to_extop(value, eop, location.segment)) {
nasm_nonfatal("expression is not simple or relocatable");
}
skip = false;
}
if (eop->dup == 0 || eop->type == EOT_NOTHING) {
@ -568,6 +592,11 @@ static int parse_eops(extop **result, bool critical, int elem)
oper_num++;
eop = NULL; /* Done with this operand */
if (skip) {
/* Consume the (last) token if that didn't happen yet */
i = stdscan(NULL, &tokval);
}
/*
* We're about to call stdscan(), which will eat the
* comma that we're currently sitting on between
@ -577,13 +606,10 @@ static int parse_eops(extop **result, bool critical, int elem)
if (i == TOKEN_EOS || i == endparen) /* Already at end? */
break;
if (i != ',') {
i = stdscan(NULL, &tokval); /* eat the comma or final paren */
if (i == TOKEN_EOS || i == ')') /* got end of expression */
break;
if (i != ',') {
nasm_nonfatal("comma expected after operand");
goto fail;
}
char *tp = tokstr(&tokval);
nasm_nonfatal("comma expected after operand, got %s", tp);
nasm_free(tp);
goto fail;
}
}

24
asm/stdscan.c
View File

@ -1,6 +1,6 @@
/* ----------------------------------------------------------------------- *
*
* Copyright 1996-2018 The NASM Authors - All Rights Reserved
* Copyright 1996-2023 The NASM Authors - All Rights Reserved
* See the file AUTHORS included with the NASM distribution for
* the specific copyright holders.
*
@ -122,19 +122,33 @@ static int stdscan_handle_brace(struct tokenval *tv)
return tv->t_type;
}
static int stdscan_token(struct tokenval *tv);
int stdscan(void *private_data, struct tokenval *tv)
{
const char *r;
int i;
(void)private_data; /* Don't warn that this parameter is unused */
nasm_zero(*tv);
stdscan_bufptr = nasm_skip_spaces(stdscan_bufptr);
tv->t_start = stdscan_bufptr;
if (!*stdscan_bufptr)
return tv->t_type = TOKEN_EOS;
/* we have a token; either an id, a number or a char */
i = stdscan_token(tv);
tv->t_len = stdscan_bufptr - tv->t_start;
return i;
}
static int stdscan_token(struct tokenval *tv)
{
const char *r;
/* we have a token; either an id, a number, operator or char */
if (nasm_isidstart(*stdscan_bufptr) ||
(*stdscan_bufptr == '$' && nasm_isidstart(stdscan_bufptr[1]))) {
/* now we've got an identifier */
@ -341,6 +355,8 @@ int stdscan(void *private_data, struct tokenval *tv)
} else if (stdscan_bufptr[0] == '|' && stdscan_bufptr[1] == '|') {
stdscan_bufptr += 2;
return tv->t_type = TOKEN_DBL_OR;
} else /* just an ordinary char */
} else {
/* just an ordinary char */
return tv->t_type = (uint8_t)(*stdscan_bufptr++);
}
}

2
include/nasm.h
View File

@ -316,6 +316,8 @@ struct tokenval {
int64_t t_inttwo;
enum token_type t_type;
int8_t t_flag;
const char *t_start; /* Pointer to token in input buffer */
int t_len; /* Length of token in input buffer */
};
typedef int (*scanner)(void *private_data, struct tokenval *tv);

5
test/baddb.asm Normal file
View File

@ -0,0 +1,5 @@
;; This should error
db 1 2
;; This should work
db 1, 2

12
travis/test/utf-error.stderr
View File

@ -1,15 +1,15 @@
./travis/test/utf.asm:63: error: __?utf16?__ must be followed by a string constant
./travis/test/utf.asm:64: error: __?utf16?__ must be followed by a string constant
./travis/test/utf.asm:63: error: __?utf16?__ must be followed by a string constant, got `33'
./travis/test/utf.asm:64: error: __?utf16?__ must be followed by a string constant, got `,'
./travis/test/utf.asm:65: error: unterminated __?utf16?__ function
./travis/test/utf.asm:66: error: unterminated __?utf16?__ function
./travis/test/utf.asm:67: error: invalid input string to __?utf16?__
./travis/test/utf.asm:69: error: __?utf16le?__ must be followed by a string constant
./travis/test/utf.asm:70: error: __?utf16le?__ must be followed by a string constant
./travis/test/utf.asm:69: error: __?utf16le?__ must be followed by a string constant, got `33'
./travis/test/utf.asm:70: error: __?utf16le?__ must be followed by a string constant, got `,'
./travis/test/utf.asm:71: error: unterminated __?utf16le?__ function
./travis/test/utf.asm:72: error: unterminated __?utf16le?__ function
./travis/test/utf.asm:73: error: invalid input string to __?utf16le?__
./travis/test/utf.asm:75: error: __?utf16be?__ must be followed by a string constant
./travis/test/utf.asm:76: error: __?utf16be?__ must be followed by a string constant
./travis/test/utf.asm:75: error: __?utf16be?__ must be followed by a string constant, got `33'
./travis/test/utf.asm:76: error: __?utf16be?__ must be followed by a string constant, got `,'
./travis/test/utf.asm:77: error: unterminated __?utf16be?__ function
./travis/test/utf.asm:78: error: unterminated __?utf16be?__ function
./travis/test/utf.asm:79: error: invalid input string to __?utf16be?__