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fuchsia-mirror
fuchsia.googlesource.com-third_party-abseil-cpp
Commits
27c30ec6
Commit
27c30ec6
authored
5 years ago
by
Roman Gershman
Committed by
Derek Mauro
5 years ago
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Avoid undefined behavior when nullptr is passed to memcpy with size 0
parent
ce65f5ac
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Changes
2
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2 changed files
absl/strings/str_cat.cc
+11
-5
11 additions, 5 deletions
absl/strings/str_cat.cc
absl/strings/str_cat_test.cc
+14
-0
14 additions, 0 deletions
absl/strings/str_cat_test.cc
with
25 additions
and
5 deletions
absl/strings/str_cat.cc
+
11
−
5
View file @
27c30ec6
...
...
@@ -89,7 +89,9 @@ static char* Append(char* out, const AlphaNum& x) {
// memcpy is allowed to overwrite arbitrary memory, so doing this after the
// call would force an extra fetch of x.size().
char
*
after
=
out
+
x
.
size
();
memcpy
(
out
,
x
.
data
(),
x
.
size
());
if
(
x
.
size
()
!=
0
)
{
memcpy
(
out
,
x
.
data
(),
x
.
size
());
}
return
after
;
}
...
...
@@ -146,8 +148,10 @@ std::string CatPieces(std::initializer_list<absl::string_view> pieces) {
char
*
out
=
begin
;
for
(
const
absl
::
string_view
piece
:
pieces
)
{
const
size_t
this_size
=
piece
.
size
();
memcpy
(
out
,
piece
.
data
(),
this_size
);
out
+=
this_size
;
if
(
this_size
!=
0
)
{
memcpy
(
out
,
piece
.
data
(),
this_size
);
out
+=
this_size
;
}
}
assert
(
out
==
begin
+
result
.
size
());
return
result
;
...
...
@@ -176,8 +180,10 @@ void AppendPieces(std::string* dest,
char
*
out
=
begin
+
old_size
;
for
(
const
absl
::
string_view
piece
:
pieces
)
{
const
size_t
this_size
=
piece
.
size
();
memcpy
(
out
,
piece
.
data
(),
this_size
);
out
+=
this_size
;
if
(
this_size
!=
0
)
{
memcpy
(
out
,
piece
.
data
(),
this_size
);
out
+=
this_size
;
}
}
assert
(
out
==
begin
+
dest
->
size
());
}
...
...
This diff is collapsed.
Click to expand it.
absl/strings/str_cat_test.cc
+
14
−
0
View file @
27c30ec6
...
...
@@ -408,6 +408,20 @@ TEST(StrCat, VectorBoolReferenceTypes) {
EXPECT_EQ
(
result
,
"1010"
);
}
// Passing nullptr to memcpy is undefined behavior and this test
// provides coverage of codepaths that handle empty strings with nullptrs.
TEST
(
StrCat
,
AvoidsMemcpyWithNullptr
)
{
EXPECT_EQ
(
absl
::
StrCat
(
42
,
absl
::
string_view
{}),
"42"
);
// Cover CatPieces code.
EXPECT_EQ
(
absl
::
StrCat
(
1
,
2
,
3
,
4
,
5
,
absl
::
string_view
{}),
"12345"
);
// Cover AppendPieces.
std
::
string
result
;
absl
::
StrAppend
(
&
result
,
1
,
2
,
3
,
4
,
5
,
absl
::
string_view
{});
EXPECT_EQ
(
result
,
"12345"
);
}
#ifdef GTEST_HAS_DEATH_TEST
TEST
(
StrAppend
,
Death
)
{
std
::
string
s
=
"self"
;
...
...
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