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Guard heredoc terminator checking by length #4266

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Merged
kddnewton merged 1 commit into from
Oct 13, 2026
Merged

Guard heredoc terminator checking by length #4266

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101 changes: 60 additions & 41 deletions src/prism.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12298,34 +12298,43 @@ parser_lex(pm_parser_t *parser) {
}
}

const uint8_t *terminator_start = ident_end - ident_length;
const uint8_t *cursor = start;
/*
* The line on which we are looking for the terminator runs
* from `start` to `ident_end`. If that line is shorter than
* the identifier, the terminator cannot fit and we skip the
* match. This also keeps `terminator_start` from pointing
* before `start`.
*/
if ((size_t) (ident_end - start) >= ident_length) {
const uint8_t *terminator_start = ident_end - ident_length;
const uint8_t *cursor = start;

if (heredoc_lex_mode->indent == PM_HEREDOC_INDENT_DASH || heredoc_lex_mode->indent == PM_HEREDOC_INDENT_TILDE) {
while (cursor < terminator_start && pm_char_is_inline_whitespace(*cursor)) {
cursor++;
if (heredoc_lex_mode->indent == PM_HEREDOC_INDENT_DASH || heredoc_lex_mode->indent == PM_HEREDOC_INDENT_TILDE) {
while (cursor < terminator_start && pm_char_is_inline_whitespace(*cursor)) {
cursor++;
}
}
}

if (
(cursor == terminator_start) &&
(memcmp(terminator_start, ident_start, ident_length) == 0)
) {
if (newline != NULL) {
pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, U32(newline - parser->start + 1));
}
if (
(cursor == terminator_start) &&
(memcmp(terminator_start, ident_start, ident_length) == 0)
) {
if (newline != NULL) {
pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, U32(newline - parser->start + 1));
}

parser->current.end = terminator_end;
if (*lex_mode->as.heredoc.next_start == '\\') {
parser->next_start = NULL;
} else {
parser->next_start = lex_mode->as.heredoc.next_start;
parser->heredoc_end = parser->current.end;
}
parser->current.end = terminator_end;
if (*lex_mode->as.heredoc.next_start == '\\') {
parser->next_start = NULL;
} else {
parser->next_start = lex_mode->as.heredoc.next_start;
parser->heredoc_end = parser->current.end;
}

lex_state_set(parser, PM_LEX_STATE_END);
lex_mode_pop(parser);
LEX(PM_TOKEN_HEREDOC_END);
lex_state_set(parser, PM_LEX_STATE_END);
lex_mode_pop(parser);
LEX(PM_TOKEN_HEREDOC_END);
}
}
}

Expand Down Expand Up @@ -12401,26 +12410,36 @@ parser_lex(pm_parser_t *parser) {
newline--; // Remove \r
}

// Start of a possible terminator.
const uint8_t *terminator_start = newline - ident_length;

// Cursor to check for the leading whitespace. We skip the
// leading whitespace if we have a - or ~ heredoc.
const uint8_t *cursor = start;

if (heredoc_lex_mode->indent == PM_HEREDOC_INDENT_DASH || heredoc_lex_mode->indent == PM_HEREDOC_INDENT_TILDE) {
while (cursor < terminator_start && pm_char_is_inline_whitespace(*cursor)) {
cursor++;
/*
* The line on which we are looking for the
* terminator runs from `start` to `newline`. If
* that line is shorter than the identifier the
* terminator cannot fit and we skip the match.
* This also keeps `terminator_start` from pointing
* before `start`.
*/
if ((size_t) (newline - start) >= ident_length) {
// Start of a possible terminator.
const uint8_t *terminator_start = newline - ident_length;

// Cursor to check for the leading whitespace. We skip the
// leading whitespace if we have a - or ~ heredoc.
const uint8_t *cursor = start;

if (heredoc_lex_mode->indent == PM_HEREDOC_INDENT_DASH || heredoc_lex_mode->indent == PM_HEREDOC_INDENT_TILDE) {
while (cursor < terminator_start && pm_char_is_inline_whitespace(*cursor)) {
cursor++;
}
}
}

if (
cursor == terminator_start &&
(memcmp(terminator_start, ident_start, ident_length) == 0)
) {
parser->current.end = breakpoint + 1;
pm_token_buffer_flush(parser, &token_buffer);
LEX(PM_TOKEN_STRING_CONTENT);
if (
cursor == terminator_start &&
(memcmp(terminator_start, ident_start, ident_length) == 0)
) {
parser->current.end = breakpoint + 1;
pm_token_buffer_flush(parser, &token_buffer);
LEX(PM_TOKEN_STRING_CONTENT);
}
}
}

Expand Down
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