Calling std::vector<>::operator[]() with an out-of-range index argument
is undefined behavior. In two cases, Crashpad used &v[0] in situations
where it was known that the address would not be used. These calls were
wrapped in conditions guarding against vector emptiness.
While s[0] is valid on an empty string, in two cases, Crashpad used
&s[0] as an argument to a system call that would be a no-op. These calls
were wrapped in similar conditions to avoid the system call.
The two uses of vector with undefined behavior were caught by the
following tests in crashpad_snapshot_test with
UndefinedBehaviorSanitizer:
[ RUN ] CrashpadInfoClientOptions.OneModule
/Users/mark/compilatorium/llvm.build/bin/../include/c++/v1/vector:1493:12:
runtime error: reference binding to null pointer of type
'crashpad::process_types::section'
[ OK ] CrashpadInfoClientOptions.OneModule (72 ms)
[ RUN ] ProcessSnapshotMinidump.Empty
/Users/mark/compilatorium/llvm.build/bin/../include/c++/v1/vector:1493:12:
runtime error: reference binding to null pointer of type
'MINIDUMP_DIRECTORY'
[ OK ] ProcessSnapshotMinidump.Empty (1 ms)
The Crashpad codebase was audited by searching for resize() calls and
analyzing how resized strings and vectors are used.
TEST=*
BUG=
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/1283243004 .
The cl_kernels bug (Apple bug 20239912) in which cl_kernels modules show
up with an __LD,__compact_unwind section inside the __TEXT segment, is
still present in Mac OS X 10.11. This results in these warnings and a
failure to load the module:
[pid:tid:yyyymmdd,hhmmss.uuuuuu:WARNING
mach_o_image_segment_reader.cc:142] section.segname incorrect in
segment __TEXT, section __LD,__compact_unwind 3/6, load command 0x19
0/6, module cl_kernels, address 0x10e964000
BUG=crashpad:42
TEST=crashpad_snapshot_test ProcessReader.*Modules
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/1276573002 .
Add MapInsertOrReplace<>() to insert a key-value pair into a map if the
key is not already present, or replace the existing value for key if the
key is present. The original value can optionally be returned to the
caller in this case.
Map insertions now use either MapInsertOrReplace<>() or
std::map<>::insert() directly.
Use MapInsertOrReplace<>() when the map should be updated to contain a
mapping from a key to a value regardless of whether the key is already
present.
Use std::map<>::insert() to insert a mapping from a key to a value
without replacing any existing mapping from a key, if present. If it is
important to know whether an existing mapping from a key was present,
use the returned std::pair<>.second. If it is important to know the
existing value, use the returned std::pair<>.first->second.
This change has a slight positive impact on performance.
TEST=crashpad_util_test MapInsert.MapInsertOrReplace and others
BUG=
R=scottmg@chromium.org
Review URL: https://codereview.chromium.org/1044273002
