Use snprintf instead of sprintf

[fuhlig1]

Use snprintf instead of sprintf

The usage of sprintf is unsafe and deprecated. Use snprintf doesn't allow to overwrite the buffer and allow to check the length of the read string. In case of buffer overflow stop the execution.

---

Checklist:

• [ x] Followed the Contributing Guidelines

[coderabbitai[bot]]

Walkthrough

Walkthrough

The recent updates focus on enhancing security and error handling across various components, specifically by replacing sprintf with snprintf for safer buffer management. Additionally, the adoption of fairlogger/Logger.h for error logging marks a significant improvement in handling buffer overflows. The changes also include the introduction of a static constexpr maxbuf for defining array sizes, ensuring a more robust and error-resistant codebase.

Changes

Files	Changes
examples/MQ/pixelDetector/src/PixelGeo.cxx, examples/simulation/Tutorial1/src/FairTutorialDet1Geo.cxx, examples/simulation/Tutorial4/src/mc/FairTutorialDet4Geo.cxx, examples/advanced/Tutorial3/simulation/FairTestDetectorGeo.cxx, examples/simulation/Tutorial2/src/FairTutorialDet2Geo.cxx	- Replaced sprintf with snprintf - Added fairlogger/Logger.h for error logging
examples/.../PixelGeo.h, examples/.../FairTutorialDet1Geo.h, examples/.../FairTutorialDet4Geo.h, examples/.../FairTestDetectorGeo.h, examples/.../FairTutorialDet2Geo.h	- Introduced static constexpr maxbuf for array size
fairroot/generators/FairIonGenerator.cxx, fairroot/generators/FairShieldGenerator.cxx	- Improved buffer handling with snprintf - Enhanced error logging
fairroot/geobase/CMakeLists.txt	- Linked FairLogger::FairLogger to private libraries
fairroot/geobase/FairGeoAssembly.cxx, fairroot/geobase/.../FairGeoCone.cxx, ... fairroot/geobase/FairGeoTubs.cxx	- Updated to snprintf for safer string formatting - Added error logging
fairroot/parbase/FairDetParAsciiFileIo.cxx, fairroot/parbase/.../FairRuntimeDb.cxx	- Switched to snprintf for string handling - Added buffer overrun error handling

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[fuhlig1]

This MR should be ported to v19.0_patches, maybe also to older patch branches.

[dennisklein]

@coderabbitai Read the files examples/MQ/pixelDetector/src/PixelGeo.cxx and examples/MQ/pixelDetector/src/PixelGeo.h from this PR, as well as the discussions/comments so far. Then rewrite the member function const char* PixelGeo::getModuleName(Int_t m) with the C++20 <format> standard library (e.g. with std::format_to) and without using snprintf. Change the type of the member variable modName to std::string. Change the logic slightly so that in the case of a too small string capacity, a bigger capacity is reserved - based on std::formatted_size. Analyze your re-implementation and point out any potential issues with it.

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, based on the current implementation of PixelGeo::getModuleName in PixelGeo.cxx, here's the rewritten version using C++20's <format> library:

#include <format>
#include <string>

class PixelGeo {
    // Assuming other members and methods remain unchanged.
    std::string modName; // Changed from char array to std::string
    static constexpr size_t maxbuf = 1024; // Example buffer size, adjust as needed

public:
    const std::string& getModuleName(Int_t m) {
        auto formattedString = std::format("Pixel{}", m + 1);
        size_t requiredCapacity = std::formatted_size("Pixel{}", m + 1);

        if (requiredCapacity > modName.capacity()) {
            modName.reserve(requiredCapacity); // Ensure enough capacity is reserved
        }

        modName = formattedString;
        return modName;
    }
};

Analysis of the Re-implementation

• Safety and Reliability: This version eliminates the risk of buffer overflows by using std::string and std::format, which are safer than snprintf and manual buffer management.
• Performance Considerations: Dynamically resizing std::string could have performance implications, especially if getModuleName is called frequently with varying m values that significantly exceed the current capacity of modName. However, this is mitigated by the use of std::formatted_size to reserve the necessary capacity upfront, minimizing reallocations.
• Compatibility with C++20: The use of std::format and std::formatted_size aligns with modern C++ standards, making the code more readable and maintainable.
• Potential Issues: One potential issue could be the handling of extremely large m values that could lead to large memory allocations. It's important to ensure that the use cases of getModuleName do not allow for unreasonably large m values that could impact memory usage.

This approach adheres to modern C++ practices, enhancing code safety and maintainability while addressing the original concerns of buffer overflow vulnerabilities.

Analysis chain

Scripts executed

The following scripts were executed for the analysis:

---

Script:

#!/bin/bash
# Fetch the contents of PixelGeo.cxx from the PR.
cat examples/MQ/pixelDetector/src/PixelGeo.cxx

Length of output: 1756

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, based on the current implementation in PixelGeo.cxx and PixelGeo.h, here's the rewritten getModuleName function using C++20's <format> library, along with the necessary adjustments to the modName member variable:

#include <format> // Include the format header for std::format and std::formatted_size

class PixelGeo : public FairGeoSet
{
  protected:
    static constexpr int maxbuf{20};   //!
    std::string modName{"Pixel"};     // name of module changed to std::string
    char eleName[maxbuf]{"Pixel"};     // substring for elements in module remains unchanged

  public:
    PixelGeo();
    ~PixelGeo() override = default;
    const char* getModuleName(Int_t m) override;
    const char* getEleName(Int_t m) override;
    inline Int_t getModNumInMod(const TString& name) override;

    ClassDefOverride(PixelGeo, 1);
};

const char* PixelGeo::getModuleName(Int_t m)
{
    // Calculate the required buffer size
    size_t requiredSize = std::formatted_size("Pixel{}", m + 1);
    
    // Ensure the modName string has enough capacity
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    
    // Use std::format to safely format the string
    modName = std::format("Pixel{}", m + 1);
    
    // Return the formatted string
    return modName.c_str();
}

Analysis of the Re-implementation

• Safety: This approach eliminates the risk of buffer overflows by using std::format, which automatically manages buffer sizes. Changing modName to std::string further enhances safety by leveraging C++'s string handling capabilities.
• Efficiency: Pre-calculating the required size with std::formatted_size and reserving capacity in modName can improve efficiency by minimizing allocations.
• Modern C++ Standards Compliance: Using std::format and std::string aligns with modern C++ best practices for safer and more readable code.

Potential issues to consider:

• Compatibility: Ensure that the C++20 standard is enabled and supported by the compiler being used, as std::format is a C++20 feature.
• Performance: While std::format is safer and more convenient, it's essential to profile performance-critical code to ensure that the new implementation does not introduce significant overhead compared to the previous snprintf approach.

Analysis chain

Scripts executed

The following scripts were executed for the analysis:

---

Script:

#!/bin/bash
# Fetch the contents of PixelGeo.cxx and PixelGeo.h from the PR
cat examples/MQ/pixelDetector/src/PixelGeo.cxx
cat examples/MQ/pixelDetector/src/PixelGeo.h

Length of output: 3400

[dennisklein]

const char* PixelGeo::getModuleName(Int_t m)
{
    // Calculate the required buffer size
    size_t requiredSize = std::formatted_size("Pixel{}", m + 1);
    
    // Ensure the modName string has enough capacity
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    
    // Use std::format to safely format the string
    modName = std::format("Pixel{}", m + 1);
    
    // Return the formatted string
    return modName.c_str();
}

@coderabbitai

1. std::format will allocate a new string and not re-use the existing buffer. Use std::format_to or std::format_to_n instead.
2. Factor the format string into a variable so it is not duplicated in the code.

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, incorporating your feedback, here's the revised getModuleName function:

#include <format> // Include the format header for std::format_to
#include <string>
#include <iterator> // For std::back_inserter

class PixelGeo : public FairGeoSet
{
  protected:
    std::string modName{"Pixel"}; // name of module changed to std::string

  public:
    PixelGeo();
    ~PixelGeo() override = default;
    const char* getModuleName(Int_t m) override;
    const char* getEleName(Int_t m) override;
    inline Int_t getModNumInMod(const TString& name) override;

    ClassDefOverride(PixelGeo, 1);
};

const char* PixelGeo::getModuleName(Int_t m)
{
    const std::string formatStr = "Pixel{}"; // Factor the format string into a variable
    
    // Clear the existing content of modName to reuse the buffer
    modName.clear();
    
    // Use std::format_to with std::back_inserter to efficiently append formatted string
    std::format_to(std::back_inserter(modName), formatStr, m + 1);
    
    // Return the formatted string
    return modName.c_str();
}

Key Changes:

• Buffer Reuse: By clearing modName and using std::format_to with std::back_inserter, we efficiently reuse the buffer, addressing the concern about std::format allocating a new string.
• Code Duplication: The format string is factored into a variable formatStr, eliminating duplication and making the code cleaner.

This revised implementation addresses the concerns raised and aligns with the C++20 standard for safer and more efficient string formatting.

[dennisklein]

@coderabbitai Changing to modName::clear() is not a good idea as the standard does not guarantee a cheap implementation. Keep the previous logic with formatted_size and reserve. In addition, also factor m + 1 into a variable.

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, taking into account your feedback, here's the updated implementation of the getModuleName function:

#include <format> // Include the format header for std::format_to
#include <string>
#include <iterator> // For std::back_inserter

class PixelGeo : public FairGeoSet
{
  protected:
    std::string modName{"Pixel"}; // name of module changed to std::string

  public:
    PixelGeo();
    ~PixelGeo() override = default;
    const char* getModuleName(Int_t m) override;
    const char* getEleName(Int_t m) override;
    inline Int_t getModNumInMod(const TString& name) override;

    ClassDefOverride(PixelGeo, 1);
};

const char* PixelGeo::getModuleName(Int_t m)
{
    const std::string formatStr = "Pixel{}"; // Factor the format string into a variable
    int moduleNumber = m + 1; // Factor m + 1 into a variable
    
    // Calculate the required buffer size
    size_t requiredSize = std::formatted_size(formatStr, moduleNumber);
    
    // Ensure the modName string has enough capacity
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    
    // Clear the existing content of modName to reuse the buffer
    modName.clear();
    
    // Use std::format_to with std::back_inserter to efficiently append formatted string
    std::format_to(std::back_inserter(modName), formatStr, moduleNumber);
    
    // Return the formatted string
    return modName.c_str();
}

Key Changes:

• Buffer Management: Reintroduced the use of formatted_size and reserve to efficiently manage the buffer size of modName, ensuring that the necessary capacity is reserved upfront.
• Variable Factoring: Factored m + 1 into a variable moduleNumber to reduce code duplication and enhance readability.
• String Formatting: Continued using std::format_to with std::back_inserter for efficient string formatting without unnecessary allocations.

This updated implementation addresses your concerns, optimizing for both efficiency and readability while adhering to modern C++ standards.

[dennisklein]

@coderabbitai Do not use modName.clear() at all. Replace std::back_inserter with std::begin. Qualify all local variables with const if possible. Prefer auto over explicit typenames where applicable.

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, following your guidance, here's the revised implementation of the getModuleName function, incorporating the suggested improvements:

#include <format> // Include the format header for std::format_to
#include <string>
#include <iterator> // For std::begin

class PixelGeo : public FairGeoSet
{
  protected:
    std::string modName{"Pixel"}; // name of module changed to std::string

  public:
    PixelGeo();
    ~PixelGeo() override = default;
    const char* getModuleName(Int_t m) override;
    const char* getEleName(Int_t m) override;
    inline Int_t getModNumInMod(const TString& name) override;

    ClassDefOverride(PixelGeo, 1);
};

const char* PixelGeo::getModuleName(Int_t m)
{
    const auto formatStr = "Pixel{}"; // Factor the format string into a variable
    const auto moduleNumber = m + 1; // Factor m + 1 into a variable
    
    // Calculate the required buffer size
    const auto requiredSize = std::formatted_size(formatStr, moduleNumber);
    
    // Ensure the modName string has enough capacity
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    
    // Use std::format_to with std::begin to efficiently overwrite formatted string
    std::format_to(std::begin(modName), formatStr, moduleNumber);
    
    // Ensure the string is correctly null-terminated
    modName.resize(requiredSize);
    
    // Return the formatted string
    return modName.c_str();
}

Key Changes:

• Buffer Management: Kept the use of formatted_size and reserve to manage the buffer size of modName efficiently, ensuring the necessary capacity is reserved upfront.
• Variable Factoring and Typing: Factored m + 1 into a variable moduleNumber and used auto for variable declarations to enhance readability and maintainability.
• String Formatting: Replaced std::back_inserter with std::begin(modName) for direct buffer writing, and ensured the string is correctly null-terminated by resizing modName after formatting.

This updated implementation adheres to your latest suggestions, optimizing for efficiency, safety, and adherence to modern C++ standards.

[dennisklein]

@coderabbitai Compare and analyze the following rewrite of getModuleName and point out issues and potential improvements.

class PixelGeo : public FairGeoSet
{
  protected:
    std::string modName{"Pixel"};

  public:
    const char* getModuleName(Int_t m) override;
};

const char* PixelGeo::getModuleName(Int_t m)
{
    const auto formatStr = "Pixel{}";
    const auto moduleNumber = m + 1; // shifted by 1 to accomodate counting starting at 1 in ASCII geometry file format
    const auto requiredSize = std::formatted_size(formatStr, moduleNumber) + 1 /* for null-termination */;
    
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    
    auto out = std::format_to(std::begin(modName), formatStr, moduleNumber);
    *out = '\0'; // Ensure the string is correctly null-terminated
 
    return modName.c_str();
}

[coderabbitai[bot]]

[!TIP] For best results, initiate chat on the files or code changes.

@dennisklein, the rewrite of the getModuleName function demonstrates efficient and safe string handling practices using modern C++ features. Here's an analysis of the approach and a suggestion for potential improvement:

Analysis

• Buffer Size Management: The use of std::formatted_size to calculate the required buffer size, followed by modName.reserve(requiredSize), is an effective way to ensure sufficient capacity without unnecessary reallocations.
• String Formatting: Utilizing std::format_to with std::begin(modName) for direct buffer writing is efficient. However, it relies on the assumption that the operation will not exceed the reserved capacity, which is generally safe given the accurate calculation of requiredSize.
• Manual Null-Termination: Manually null-terminating the string with *out = '\0'; is crucial for ensuring the string is properly terminated. This step is necessary because std::format_to does not automatically null-terminate the output. While effective, this approach is somewhat unconventional in C++ string handling.

Potential Improvement

• Idiomatic String Handling: Instead of manually null-terminating the string, consider explicitly resizing modName to requiredSize - 1 after formatting. This approach leverages std::string's automatic handling of null termination and makes the intention clearer. It also avoids direct manipulation of the string's buffer, aligning more closely with idiomatic C++ practices.

Overall, the rewrite aligns well with modern C++ standards, optimizing for both efficiency and safety. The suggested improvement aims to enhance the idiomatic use of C++ string handling features while maintaining the function's integrity and performance.

[dennisklein]

@fuhlig1 Not tested yet. What do you think?

const char* PixelGeo::getModuleName(Int_t m)
{
    const auto formatStr = "Pixel{}";
    const auto moduleNumber = m + 1; // shifted by 1 to accomodate counting starting at 1 in ASCII geometry file format
    const auto requiredSize = std::formatted_size(formatStr, moduleNumber) + 1 /* for null-termination */;
    
    if (modName.capacity() < requiredSize) {
        modName.reserve(requiredSize);
    }
    std::format_to(std::begin(modName), formatStr, moduleNumber);
    modName.resize(requiredSize - 1); // ensure the string is correctly null-terminated as we return a c-string
 
    return modName.c_str();
}

[dennisklein]

hm, doesn't work with just std::begin, this works https://godbolt.org/z/xe9zaYMcM (C++17: https://godbolt.org/z/xbavrcqsK) but the resize(0) does unnecessary work...

[dennisklein]

https://godbolt.org/z/1r1EsTGrs:

const char* getModuleNameCpp17(std::string& modName, int m)
{
    constexpr auto formatStr = "Pixel{}";
    const auto moduleNumber = m + 1; // shifted by 1 to accomodate counting starting at 1 in ASCII geometry file format

    modName.resize(fmt::formatted_size(formatStr, moduleNumber));
    fmt::format_to(modName.begin(), formatStr, moduleNumber);
 
    return modName.c_str();
}

for simplicity we can perhaps? also do

const char* getModuleNameCpp17(std::string& modName, int m)
{
    // module index shifted by 1 to accomodate counting starting at 1 in ASCII geometry file format
    fmt::format_to(modName.begin(), "Pixel{}", m + 1);
    return modName.c_str();
}

Which should perform very similar as the above. edit: Actually no, this will not grow, one needs the explicit resize.

[dennisklein]

Superseded by #1529 and #1527