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[lldb][NFC] Make GetShellSafeArgument simpler and faster 

Escaping by inserting characters in the middle of a std::string isn't cheap.
It's much more verbose than just prepending a backslash in a loop.
This commit is contained in:
Raphael Isemann 2020-10-26 15:03:58 +01:00
parent 16f126df43
commit d0ee1d8efe
1 changed files with 9 additions and 12 deletions
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21
lldb/source/Utility/Args.cpp
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@ -383,7 +383,7 @@ std::string Args::GetShellSafeArgument(const FileSpec &shell,
llvm::StringRef unsafe_arg) {
struct ShellDescriptor {
ConstString m_basename;
const char *m_escapables;
llvm::StringRef m_escapables;
};
static ShellDescriptor g_Shells[] = {{ConstString("bash"), " '\"<>()&"},
@ -391,7 +391,7 @@ std::string Args::GetShellSafeArgument(const FileSpec &shell,
{ConstString("sh"), " '\"<>()&"}};
// safe minimal set
const char *escapables = " '\"";
llvm::StringRef escapables = " '\"";
if (auto basename = shell.GetFilename()) {
for (const auto &Shell : g_Shells) {
@ -402,16 +402,13 @@ std::string Args::GetShellSafeArgument(const FileSpec &shell,
}
}
std::string safe_arg(unsafe_arg);
size_t prev_pos = 0;
while (prev_pos < safe_arg.size()) {
// Escape spaces and quotes
size_t pos = safe_arg.find_first_of(escapables, prev_pos);
if (pos != std::string::npos) {
safe_arg.insert(pos, 1, '\\');
prev_pos = pos + 2;
} else
break;
std::string safe_arg;
safe_arg.reserve(unsafe_arg.size());
// Add a \ before every character that needs to be escaped.
for (char c : unsafe_arg) {
if (escapables.contains(c))
safe_arg.push_back('\\');
safe_arg.push_back(c);
}
return safe_arg;
}