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Codechange: Pass buffers for TarFile's ExtractString as span. (#12567) 

ExtractString does not need to find a string terminator as StrMakeValid already does this, so simply pass the full bounds of the buffer.

Removes lengthof, array indices, and needs only the buffer as a parameter.
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Peter Nelson 2024-04-24 21:34:21 +01:00 committed by GitHub
parent 5159aa81d4
commit e8249e9075
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1 changed files with 8 additions and 11 deletions
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19
src/fileio.cpp
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@ -473,17 +473,14 @@ bool TarScanner::AddFile(Subdirectory sd, const std::string &filename)
* header contains garbage and is malicious. So, we cannot rely on the string
* being properly terminated.
* As such, do not use strlen to determine the actual length (explicitly or
* implictly via the std::string constructor), but also do not create a string
* of the buffer length as that makes the string contain essentially garbage.
* implictly via the std::string constructor), but pass the buffer bounds
* explicitly.
* @param buffer The buffer to read from.
* @param buffer_length The length of the buffer to read from.
* @return The string data.
*/
static std::string ExtractString(char *buffer, size_t buffer_length)
static std::string ExtractString(std::span<char> buffer)
{
size_t length = 0;
for (; length < buffer_length && buffer[length] != '\0'; length++) {}
return StrMakeValid(std::string_view(buffer, length));
return StrMakeValid(std::string_view(buffer.begin(), buffer.end()));
}
bool TarScanner::AddFile(const std::string &filename, size_t, [[maybe_unused]] const std::string &tar_filename)
@ -557,15 +554,15 @@ bool TarScanner::AddFile(const std::string &filename, size_t, [[maybe_unused]] c
/* The prefix contains the directory-name */
if (th.prefix[0] != '\0') {
name = ExtractString(th.prefix, lengthof(th.prefix));
name = ExtractString(th.prefix);
name += PATHSEP;
}
/* Copy the name of the file in a safe way at the end of 'name' */
name += ExtractString(th.name, lengthof(th.name));
name += ExtractString(th.name);
/* The size of the file, for some strange reason, this is stored as a string in octals. */
std::string size = ExtractString(th.size, lengthof(th.size));
std::string size = ExtractString(th.size);
size_t skip = size.empty() ? 0 : std::stoul(size, nullptr, 8);
switch (th.typeflag) {
@ -591,7 +588,7 @@ bool TarScanner::AddFile(const std::string &filename, size_t, [[maybe_unused]] c
case '1': // hard links
case '2': { // symbolic links
/* Copy the destination of the link in a safe way at the end of 'linkname' */
std::string link = ExtractString(th.linkname, lengthof(th.linkname));
std::string link = ExtractString(th.linkname);
if (name.empty() || link.empty()) break;