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tmpfile_windows: fix temp file name collisions when appending an extension 

Formerly, tmpnam_s was used to ensure a unique file name, but then we'd
append an extension to it, invalidating its uniqueness. Instead, we now
do our own uniqueness check by attempting to create a unique empty file
for write with new names until it succeeds.

Bug: tint:812
Change-Id: I90b85074ad2281f9904f24e8fddda80d67e61ba7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/53061
Auto-Submit: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
This commit is contained in:
Antonio Maiorano 2021-06-02 23:22:44 +00:00 committed by Tint LUCI CQ
parent a7f47b49e7
commit 8324d227a1
1 changed files with 14 additions and 5 deletions
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19
src/utils/io/tmpfile_windows.cc
View File

@ -22,17 +22,26 @@ namespace utils {
namespace { namespace {
std::string TmpFilePath() { std::string TmpFilePath(const std::string& ext) {
char name[L_tmpnam]; char name[L_tmpnam];
if (tmpnam_s(name, L_tmpnam - 1) == 0) { // As we're adding an extension, to ensure the file is really unique, try
return name; // creating it, failing if it already exists.
while (tmpnam_s(name, L_tmpnam - 1) == 0) {
std::string name_with_ext = std::string(name) + ext;
FILE* f = nullptr;
// The "x" arg forces the function to fail if the file already exists.
fopen_s(&f, name_with_ext.c_str(), "wbx");
if (f) {
fclose(f);
return name_with_ext;
}
} }
return ""; return {};
} }
} // namespace } // namespace
TmpFile::TmpFile(std::string ext) : path_(TmpFilePath() + ext) {} TmpFile::TmpFile(std::string ext) : path_(TmpFilePath(ext)) {}
TmpFile::~TmpFile() { TmpFile::~TmpFile() {
if (!path_.empty()) { if (!path_.empty()) {