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Catch more zero-index expressions

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This expands the sanity check for literal zero indexes that was not
updated when range expansions was introduced.

Closes #8213
This commit is contained in:
Mahmoud Al-Qudsi 2021-08-15 13:40:45 -05:00
parent 7f34b8ab53
commit 5326462116
1 changed files with 46 additions and 33 deletions
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79
src/expand.cpp
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@ -174,16 +174,21 @@ wcstring expand_escape_string(const wcstring &el) {
return buff;
}
enum class parse_slice_error_t {
none,
zero_index,
invalid_index,
};
/// Parse an array slicing specification Returns 0 on success. If a parse error occurs, returns the
/// index of the bad token. Note that 0 can never be a bad index because the string always starts
/// with [.
static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long> &idx,
size_t array_size) {
static size_t parse_slice(const wchar_t * const in, wchar_t ** const end_ptr,
std::vector<long> &idx, size_t array_size, parse_slice_error_t * const error) {
const long size = static_cast<long>(array_size);
size_t pos = 1; // skip past the opening square brace
int zero_index = -1;
bool literal_zero_index = true;
*error = parse_slice_error_t::none;
while (true) {
while (iswspace(in[pos]) || (in[pos] == INTERNAL_SEPARATOR)) pos++;
@ -192,17 +197,6 @@ static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long
break;
}
// Explicitly refuse $foo[0] as valid syntax, regardless of whether or not we're going
// to show an error if the index ultimately evaluates to zero. This will help newcomers
// to fish avoid a common off-by-one error. See #4862.
if (literal_zero_index) {
if (in[pos] == L'0') {
zero_index = pos;
} else {
literal_zero_index = false;
}
}
const wchar_t *end;
long tmp;
if (idx.empty() && in[pos] == L'.' && in[pos + 1] == L'.') {
@ -216,6 +210,13 @@ static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long
// We don't test `*end` as is typically done because we expect it to not be the null
// char. Ignore the case of errno==-1 because it means the end char wasn't the null
// char.
*error = parse_slice_error_t::invalid_index;
return pos;
} else if (tmp == 0) {
// Explicitly refuse $foo[0] as valid syntax, regardless of whether or not we're going
// to show an error if the index ultimately evaluates to zero. This will help newcomers
// to fish avoid a common off-by-one error. See #4862.
*error = parse_slice_error_t::zero_index;
return pos;
}
}
@ -238,6 +239,10 @@ static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long
tmp1 = fish_wcstol(&in[pos], &end);
// Ignore the case of errno==-1 because it means the end char wasn't the null char.
if (errno > 0) {
*error = parse_slice_error_t::invalid_index;
return pos;
} else if (tmp1 == 0) {
*error = parse_slice_error_t::zero_index;
return pos;
}
}
@ -268,14 +273,9 @@ static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long
continue;
}
literal_zero_index = literal_zero_index && tmp == 0;
idx.push_back(i1);
}
if (literal_zero_index && zero_index != -1) {
return zero_index;
}
if (end_ptr) {
*end_ptr = const_cast<wchar_t *>(in + pos);
}
@ -385,14 +385,20 @@ static expand_result_t expand_variables(wcstring instr, completion_receiver_t *o
} else if (history) {
effective_val_count = history->size();
}
size_t bad_pos =
parse_slice(in + slice_start, &slice_end, var_idx_list, effective_val_count);
parse_slice_error_t parse_error;
size_t bad_pos = parse_slice(in + slice_start, &slice_end, var_idx_list, effective_val_count, &parse_error);
if (bad_pos != 0) {
if (in[slice_start + bad_pos] == L'0') {
append_syntax_error(errors, slice_start + bad_pos,
L"array indices start at 1, not 0.");
} else {
append_syntax_error(errors, slice_start + bad_pos, L"Invalid index value");
switch (parse_error) {
case parse_slice_error_t::none:
assert(false && "bad_pos != 0 but parse_slice_error_t::none!");
break;
case parse_slice_error_t::zero_index:
append_syntax_error(errors, slice_start + bad_pos,
L"array indices start at 1, not 0.");
break;
case parse_slice_error_t::invalid_index:
append_syntax_error(errors, slice_start + bad_pos, L"Invalid index value");
break;
}
return expand_result_t::make_error(STATUS_EXPAND_ERROR);
}
@ -679,13 +685,20 @@ static expand_result_t expand_cmdsubst(wcstring input, const operation_context_t
std::vector<long> slice_idx;
const wchar_t *const slice_begin = in + tail_begin;
wchar_t *slice_end = nullptr;
size_t bad_pos = parse_slice(slice_begin, &slice_end, slice_idx, sub_res.size());
parse_slice_error_t parse_error;
size_t bad_pos = parse_slice(slice_begin, &slice_end, slice_idx, sub_res.size(), &parse_error);
if (bad_pos != 0) {
if (slice_begin[bad_pos] == L'0') {
append_syntax_error(errors, slice_begin - in + bad_pos,
L"array indices start at 1, not 0.");
} else {
append_syntax_error(errors, slice_begin - in + bad_pos, L"Invalid index value");
switch (parse_error) {
case parse_slice_error_t::none:
assert(false && "bad_pos != 0 but parse_slice_error_t::none!");
break;
case parse_slice_error_t::zero_index:
append_syntax_error(errors, slice_begin - in + bad_pos,
L"array indices start at 1, not 0.");
break;
case parse_slice_error_t::invalid_index:
append_syntax_error(errors, slice_begin - in + bad_pos, L"Invalid index value");
break;
}
return expand_result_t::make_error(STATUS_EXPAND_ERROR);
}