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Fix gzopen/gzclose correctness issues #66

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Merged
asonje merged 2 commits into from
Jul 30, 2026
Merged

Fix gzopen/gzclose correctness issues #66

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e199188
Fix gzopen/gzclose correctness issues
mulugetam Jul 28, 2026
8b44479
gzclose: unregister the file before closing it
asonje Jul 30, 2026
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18 changes: 14 additions & 4 deletions zlib_accel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -923,8 +923,14 @@ gzFile ZEXPORT gzopen(const char* path, const char* mode) {
FileMode file_mode = FileMode::NONE;
int oflag = GetOpenFlags(mode, &file_mode);
int fd = open((const char*)path, oflag, 0666);
if (fd < 0) {
return nullptr;
}
gzFile file = orig_gzdopen(fd, mode);
// TODO in case of error fall back to zlib and set execution path.
if (file == nullptr) {
close(fd);
return nullptr;
}

Log(LogLevel::LOG_INFO, "gzopen Line ", __LINE__, ", file ",
static_cast<void*>(file), ", path ", path, ", mode ", mode, "\n");
Expand Down Expand Up @@ -1323,6 +1329,12 @@ int ZEXPORT gzread(gzFile file, voidp buf, unsigned len) {
int ZEXPORT gzclose(gzFile file) {
auto gz = gzip_files.Get(file);

// Unregister up front, before orig_gzclose frees the gzFile. Unsetting after
// the free would erase the entry of whatever file has since been allocated at
// the same address, so do it once here rather than on each exit path. Holding
// gz (a shared_ptr) keeps this file's state alive until we return.
gzip_files.Unset(file);

Log(LogLevel::LOG_INFO, "gzclose Line ", __LINE__, ", file ",
static_cast<void*>(file), ", buffered ", gz->data_buf_content, ", path ",
static_cast<int>(gz->path), "\n");
Expand All @@ -1337,14 +1349,13 @@ int ZEXPORT gzclose(gzFile file) {
}

// Capture file size and name before gzclose
int file_size = lseek(gz->fd, 0, SEEK_CUR);
off_t file_size = lseek(gz->fd, 0, SEEK_CUR);
char file_path[MAXPATHLEN];
ssize_t readlink_ret =
readlink(("/proc/self/fd/" + std::to_string(gz->fd)).c_str(), file_path,
MAXPATHLEN - 1);
if (readlink_ret == -1) {
ret = orig_gzclose(file);
gzip_files.Unset(file);
Log(LogLevel::LOG_ERROR, "gzclose Line ", __LINE__,
", readlink_ret return error \n");
return ret;
Expand Down Expand Up @@ -1373,7 +1384,6 @@ int ZEXPORT gzclose(gzFile file) {
Log(LogLevel::LOG_INFO, "gzclose Line ", __LINE__, ", file ",
static_cast<void*>(file), ", return code ", ret, ", buffered processed ",
gz->data_buf_pos, "\n");
gzip_files.Unset(file);
return ret;
}

Expand Down