{"record":{"id":"124a7232293950da","repo":"Yalantis/uCrop","slug":"cimg-load-network-specified-destination-string","errorCode":null,"errorMessage":"cimg::load_network(): Specified destination string is (null).","messagePattern":"cimg::load_network\\(\\): Specified destination string is \\(null\\)\\.","errorType":"exception","errorClass":"CImgArgumentException","httpStatus":null,"severity":"error","filePath":"ucrop/src/main/jni/CImg.h","lineNumber":70063,"sourceCode":"\n    //! Load file from network as a local temporary file.\n    /**\n       \\param url URL of the filename, as a C-string.\n       \\param[out] filename_local C-string containing the path to a local copy of \\c filename.\n       \\param timeout Maximum time (in seconds) authorized for downloading the file from the URL.\n       \\param try_fallback When using libcurl, tells using system calls as fallbacks in case of libcurl failure.\n       \\param referer Referer used, as a C-string.\n       \\param user_agent User agent used, as a C-string.\n       \\return Value of \\c filename_local.\n       \\note Use the \\c libcurl library, or the external binaries \\c wget or \\c curl to perform the download.\n    **/\n    inline char *load_network(const char *const url, char *const filename_local,\n                              const unsigned int timeout, const bool try_fallback,\n                              const char *const referer, const char *const user_agent) {\n      if (!url)\n        throw CImgArgumentException(\"cimg::load_network(): Specified URL is (null).\");\n      if (!filename_local)\n        throw CImgArgumentException(\"cimg::load_network(): Specified destination string is (null).\");\n      if (!network_mode())\n        throw CImgIOException(\"cimg::load_network(): Loading files from network is disabled.\");\n\n      const char *const __ext = cimg::split_filename(url), *const _ext = (*__ext && __ext>url)?__ext - 1:__ext;\n      CImg<char> ext = CImg<char>::string(_ext);\n      *filename_local = 0;\n      if (ext._width>16 || !cimg::strncasecmp(ext,\"cgi\",3)) *ext = 0;\n      else cimg::strwindows_reserved(ext);\n      do {\n        cimg_snprintf(filename_local,256,\"%s%c%s%s\",\n                      cimg::temporary_path(),cimg_file_separator,cimg::filenamerand(),ext._data);\n      } while (cimg::path_exists(filename_local));\n\n#ifdef cimg_use_curl\n      const unsigned int omode = cimg::exception_mode();\n      cimg::exception_mode(0);\n      try {\n        CURL *curl = 0;","sourceCodeStart":70045,"sourceCodeEnd":70081,"githubUrl":"https://github.com/Yalantis/uCrop/blob/f788b534b48c144edf786c8cddbf0e029e637804/ucrop/src/main/jni/CImg.h#L70045-L70081","documentation":"cimg::load_network() requires a writable local destination buffer (char*) where the downloaded file path is stored. This CImgArgumentException is thrown when that destination pointer is null. The URL may be perfectly valid — only the output location is missing.","triggerScenarios":"Calling cimg::load_network(url, NULL, timeout, ...) directly, or passing an uninitialized/failed std::vector<char>.data(), or a null local-path variable forwarded from a wrapper like CImg<T>::load_network.","commonSituations":"Callers who only prepared the URL and forgot the destination string; dynamic allocation that failed and returned null without being checked; JNI code dropping the local-path parameter.","solutions":["Allocate/prepare a non-null destination buffer (sufficient for the resulting local filename) before the call.","Check any pointer-producing expression (malloc, .data(), c_str() of a temporary) for null before passing it.","Catch CImgArgumentException to report 'missing destination path' instead of a native crash.","Simplify by passing a std::string-backed buffer owned for the call's duration."],"exampleFix":"// before\nchar *local = NULL;\ncimg::load_network(url, local, 0, true, 0, 0); // throws\n// after\nchar local[1024];\ncimg::load_network(url, local, 0, true, 0, 0);","handlingStrategy":"validation","validationCode":"char localPath[1024]; // preallocated before the call\ncimg::load_network(url, localPath, 30, true, 0, 0);","typeGuard":"bool writableBuffer(char *buf, size_t n) { return buf != nullptr && n >= 512; }","tryCatchPattern":"try { img.load_network(url, local, 30, true, 0, 0); } catch (const CImgArgumentException &e) { fprintf(stderr, \"destination buffer missing: %s\", e.what()); }","preventionTips":["Always pass a stack buffer or properly sized std::vector<char> as the destination","Check the result of dynamic allocation before passing pointers into CImg","Keep the destination buffer alive for the duration of the call (no temporaries)","Wrap load_network in a helper with a std::string destination to make misuse harder"],"tags":["null-argument","network","cimg"],"backgroundTag":"null-argument","analyzedSha":"f788b534b48c144edf786c8cddbf0e029e637804","analyzedAt":"2026-09-08T08:36:04.887Z","contentChangedAt":"2026-09-08T08:36:04.887Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}