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Adding a method to uncompress a gzipped std::string #420

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5b99706
TRestTools::GzipInflate added
jgalan May 16, 2023
ec48069
Merge branch 'master' into jgalan_tools_gzip
jgalan May 21, 2023
8d69da3
Merge branch 'master' into jgalan_tools_gzip
jgalan May 31, 2023
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2 changes: 2 additions & 0 deletions source/framework/tools/inc/TRestTools.h
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Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,8 @@ class TRestTools {

static std::string POSTRequest(const std::string& url, const std::map<std::string, std::string>& keys);
static void ChangeDirectory(const std::string& toDirectory);

static bool GzipInflate(const std::string& compressedBytes, std::string& uncompressedBytes);
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I think we should avoid passing mutable references and instead use the method's return. One strong reason to avoid doing so is that these functions are much more difficult to call from the python bindings (it's possible but much more complicated as just passing python objects as strings and so on).

};

namespace REST_InitTools {
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69 changes: 69 additions & 0 deletions source/framework/tools/src/TRestTools.cxx
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Expand Up @@ -51,6 +51,9 @@
#include <curl/curl.h>
#endif

#include "zconf.h"
#include "zlib.h"

#ifdef WIN32
#include <io.h>
#else
Expand Down Expand Up @@ -1264,3 +1267,69 @@ string ToTimeStringLong(double seconds) {
return TString::Format("%.2f %s", seconds / (60.0 * 60.0 * 24.0), "days").Data();
}
}

///////////////////////////////////////////////
/// It will decompress a std::string that has been initialized from a gzip file.
///
bool TRestTools::GzipInflate(const std::string& compressedBytes, std::string& uncompressedBytes) {
if (compressedBytes.size() == 0) {
uncompressedBytes = compressedBytes;
return true;
}

uncompressedBytes.clear();

unsigned full_length = compressedBytes.size();
unsigned half_length = compressedBytes.size() / 2;

unsigned uncompLength = full_length;
char* uncomp = (char*)calloc(sizeof(char), uncompLength);

z_stream strm;
strm.next_in = (Bytef*)compressedBytes.c_str();
strm.avail_in = compressedBytes.size();
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;

bool done = false;

if (inflateInit2(&strm, (16 + MAX_WBITS)) != Z_OK) {
free(uncomp);
return false;
}

while (!done) {
// If our output buffer is too small
if (strm.total_out >= uncompLength) {
// Increase size of output buffer
char* uncomp2 = (char*)calloc(sizeof(char), uncompLength + half_length);
memcpy(uncomp2, uncomp, uncompLength);
uncompLength += half_length;
free(uncomp);
uncomp = uncomp2;
}

strm.next_out = (Bytef*)(uncomp + strm.total_out);
strm.avail_out = uncompLength - strm.total_out;

// Inflate another chunk.
int err = inflate(&strm, Z_SYNC_FLUSH);
if (err == Z_STREAM_END)
done = true;
else if (err != Z_OK) {
break;
}
}

if (inflateEnd(&strm) != Z_OK) {
free(uncomp);
return false;
}

for (size_t i = 0; i < strm.total_out; ++i) {
uncompressedBytes += uncomp[i];
}
free(uncomp);
return true;
}