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Avoid a crash in source_cache::extract_lines

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If the first requested line is larger than the number of lines in the
source buffer, source_cache::extract_lines could crash, because it
would try to pass string::npos" to string::substr.

This patch avoids the crash by checking for this case.

This version of the patch changes get_source_lines to return
std::string.

gdb/ChangeLog
2019-03-14  Tom Tromey  <tromey@adacore.com>

	* source-cache.h (class source_cache) <get_source_lines>: Return
	std::string.
	* source-cache.c (source_cache::extract_lines): Handle case where
	first_pos==npos.  Return std::string.
	(source_cache::get_source_lines): Update.
This commit is contained in:
Tom Tromey 2019-03-08 13:59:27 -07:00
parent d085f98901
commit 3b336828de
3 changed files with 25 additions and 11 deletions
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8
gdb/ChangeLog
View File

@ -1,3 +1,11 @@
2019-03-14 Tom Tromey <tromey@adacore.com>
* source-cache.h (class source_cache) <get_source_lines>: Return
std::string.
* source-cache.c (source_cache::extract_lines): Handle case where
first_pos==npos. Return std::string.
(source_cache::get_source_lines): Update.
2019-03-14 Tom Tromey <tromey@adacore.com>
* NEWS: Add item for "style sources" commands.

21
gdb/source-cache.c
View File

@ -84,9 +84,9 @@ source_cache::get_plain_source_lines (struct symtab *s, int first_line,
/* See source-cache.h. */
bool
std::string
source_cache::extract_lines (const struct source_text &text, int first_line,
int last_line, std::string *lines)
int last_line)
{
int lineno = 1;
std::string::size_type pos = 0;
@ -102,16 +102,17 @@ source_cache::extract_lines (const struct source_text &text, int first_line,
pos = new_pos;
if (lineno == last_line || pos == std::string::npos)
{
if (first_pos == std::string::npos)
return {};
if (pos == std::string::npos)
pos = text.contents.size ();
*lines = text.contents.substr (first_pos, pos - first_pos);
return true;
return text.contents.substr (first_pos, pos - first_pos);
}
++lineno;
++pos;
}
return false;
return {};
}
#ifdef HAVE_SOURCE_HIGHLIGHT
@ -187,7 +188,10 @@ source_cache::get_source_lines (struct symtab *s, int first_line,
for (const auto &item : m_source_map)
{
if (item.fullname == fullname)
return extract_lines (item, first_line, last_line, lines);
{
*lines = extract_lines (item, first_line, last_line);
return true;
}
}
const char *lang_name = get_language_name (SYMTAB_LANGUAGE (s));
@ -208,8 +212,9 @@ source_cache::get_source_lines (struct symtab *s, int first_line,
if (m_source_map.size () > MAX_ENTRIES)
m_source_map.erase (m_source_map.begin ());
return extract_lines (m_source_map.back (), first_line,
last_line, lines);
*lines = extract_lines (m_source_map.back (), first_line,
last_line);
return true;
}
}
}

7
gdb/source-cache.h
View File

@ -65,9 +65,10 @@ private:
int last_line, std::string *lines_out);
/* A helper function for get_plain_source_lines that extracts the
desired source lines from TEXT, putting them into LINES_OUT. The
arguments and return value are as for get_source_lines. */
bool extract_lines (const struct source_text &text, int first_line,
int last_line, std::string *lines_out);
arguments are as for get_source_lines. The return value is the
desired lines. */
std::string extract_lines (const struct source_text &text, int first_line,
int last_line);
/* The contents of the cache. */
std::vector<source_text> m_source_map;