[Path] Fix off-by-one in finding filename for win style paths#78055
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[Path] Fix off-by-one in finding filename for win style paths#78055
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@llvm/pr-subscribers-llvm-support Author: Matheus Izvekov (mizvekov) ChangesThis fixes a crash where On Windows machine, with runtime checks enabled build, upon Ideally, we can look for the last colon starting from the last character, but we can instead start from second to last, and handle empty paths by abusing Full diff: https://github.com/llvm/llvm-project/pull/78055.diff 2 Files Affected:
diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index c2456dcac0974a..1c441100679ed7 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -104,7 +104,7 @@ namespace {
if (is_style_windows(style)) {
if (pos == StringRef::npos)
- pos = str.find_last_of(':', str.size() - 2);
+ pos = str.find_last_of(':', str.size() - 1);
}
if (pos == StringRef::npos || (pos == 1 && is_separator(str[0], style)))
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index a7b7e6a0f5044d..837ca03216f87a 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -190,6 +190,7 @@ TEST(Support, Path) {
paths.push_back("c:\\foo\\");
paths.push_back("c:\\foo/");
paths.push_back("c:/foo\\bar");
+ paths.push_back(":");
for (SmallVector<StringRef, 40>::const_iterator i = paths.begin(),
e = paths.end();
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dwblaikie
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Jan 17, 2024
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dwblaikie
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Didn't think about it too hard - but sounds plausible.
This fixes a crash where `path::parent_path` causes an invalid access on a string upon receiving a path that consists of a single colon. On Windows machine, with runtime checks enabled build, upon `clang -I: test.cc` produces: ``` Assertion failed: Index < Length && "Invalid index!", file llvm\include\llvm/ADT/StringRef.h, line 232 ... #6 0x00007ff7816201eb `anonymous namespace'::parent_path_end llvm\lib\Support\Path.cpp:144:0 #7 0x00007ff781620135 llvm::sys::path::parent_path(class llvm::StringRef, enum llvm::sys::path::Style) llvm\lib\Support\Path.cpp:470:0 ``` Ideally, we can look for the last colon starting from the last character, but we can instead start from second to last, and handle empty paths by abusing `0 - 1 == npos`.
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…8055) This fixes a crash where `path::parent_path` causes an invalid access on a string upon receiving a path that consists of a single colon. On Windows machine, with runtime checks enabled build, upon `clang -I: test.cc` produces: ``` Assertion failed: Index < Length && "Invalid index!", file llvm\include\llvm/ADT/StringRef.h, line 232 ... llvm#6 0x00007ff7816201eb `anonymous namespace'::parent_path_end llvm\lib\Support\Path.cpp:144:0 llvm#7 0x00007ff781620135 llvm::sys::path::parent_path(class llvm::StringRef, enum llvm::sys::path::Style) llvm\lib\Support\Path.cpp:470:0 ``` Ideally, we can look for the last colon starting from the last character, but we can instead start from second to last, and handle empty paths by abusing `0 - 1 == npos`.
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This fixes a crash where
path::parent_pathcauses an invalid access on a string upon receiving a path that consists of a single colon.On Windows machine, with runtime checks enabled build, upon
clang -I: test.ccproduces:Ideally, we can look for the last colon starting from the last character, but we can instead start from second to last, and handle empty paths by abusing
0 - 1 == npos.