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Fix the assertion failure in expand_variables()

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expand_variables() is slightly confused about how to handle last_idx. On
input, it expects it to be the index to start processing at, but when
called recursively it always passes the current index. This means that
it may sometimes pass an index 1 past the end of the input string.
Notably, that happens when typing something like

> echo "$foo

(where "foo" is any string that is not a prefix of some existing
variable name)

Fix this by explicitly defining last_idx as being the last processed
index, meaning the next index to process is actually last_idx-1. This
means we should call it with next.size() instead of next.size()-1.
This commit is contained in:
Kevin Ballard 2014-08-28 13:19:38 -07:00
parent 02a07164f3
commit b92a09d5e7
1 changed files with 14 additions and 9 deletions
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19
expand.cpp
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@ -1051,14 +1051,20 @@ static size_t parse_slice(const wchar_t *in, wchar_t **end_ptr, std::vector<long
and do proper testing afterwards. and do proper testing afterwards.
This function operates on strings backwards, starting at last_idx. This function operates on strings backwards, starting at last_idx.
Note: last_idx is considered to be where it previously finished
procesisng. This means it actually starts operating on last_idx-1.
As such, to process a string fully, pass string.size() as last_idx
instead of string.size()-1.
*/ */
static int expand_variables(parser_t &parser, const wcstring &instr, std::vector<completion_t> &out, long last_idx, parse_error_list_t *errors) static int expand_variables(parser_t &parser, const wcstring &instr, std::vector<completion_t> &out, long last_idx, parse_error_list_t *errors)
{ {
// We permit last_idx to be beyond the end of the string if and only if the string is empty const size_t insize = instr.size();
assert(instr.empty() || (last_idx >= 0 && (size_t)last_idx < instr.size()));
// Make this explicit // last_idx may be 1 past the end of the string, but no further
if (instr.empty()) assert(last_idx >= 0 && (size_t)last_idx <= insize);
if (last_idx == 0)
{ {
append_completion(out, instr); append_completion(out, instr);
return true; return true;
@ -1066,7 +1072,6 @@ static int expand_variables(parser_t &parser, const wcstring &instr, std::vector
bool is_ok = true; bool is_ok = true;
bool empty = false; bool empty = false;
const size_t insize = instr.size();
wcstring var_tmp; wcstring var_tmp;
@ -1078,7 +1083,7 @@ static int expand_variables(parser_t &parser, const wcstring &instr, std::vector
// CHECK( out, 0 ); // CHECK( out, 0 );
for (long i=last_idx; (i>=0) && is_ok && !empty; i--) for (long i=last_idx-1; (i>=0) && is_ok && !empty; i--)
{ {
const wchar_t c = instr.at(i); const wchar_t c = instr.at(i);
if ((c == VARIABLE_EXPAND) || (c == VARIABLE_EXPAND_SINGLE)) if ((c == VARIABLE_EXPAND) || (c == VARIABLE_EXPAND_SINGLE))
@ -1809,7 +1814,7 @@ int expand_string(const wcstring &input, std::vector<completion_t> &output, expa
} }
else else
{ {
if (!expand_variables(parser, next, *out, next.size() - 1, errors)) if (!expand_variables(parser, next, *out, next.size(), errors))
{ {
return EXPAND_ERROR; return EXPAND_ERROR;
} }