this cleaned up functions and global constants and hid them away in to their header and source files

CMakeLists.txt

@@ -4,4 +4,4 @@ project(Tarstats__)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror -std=c++20")
 
-add_executable(tarstats_pp main.cpp)
+add_executable(tarstats_pp main.cpp tarconst.h tarfunc.cpp tarfunc.h)

main.cpp

@@ -1,95 +1,30 @@
+/*
+ * by Marcel Nowicki (github@epenis.de | github.com/blindi0815)
+ */
+
 #include <iostream>
 #include <fstream>
 #include <string>
 #include <vector>
-#include <cmath>
 #include <map>
 #include <filesystem>
-
-// global itemtype definition
-std::string const typeFile = "FILES";
-std::string const typeDir = "DIRECTORIES";
-std::string const typeSym = "SYMLINKS";
-std::string const typeHard = "HARDLINKS";
-std::string const typeOther = "OTHER";
-
-// checks if a valid modern tar file - ustar
-bool validTar (std::istream & file) {
-    file.seekg(257);
-    char* buffer = new char [6];
-    file.read(buffer, 6);
-    std::string magicfield(&buffer[0], 5);
-    delete[] buffer;
-    file.seekg(0);
-    return magicfield == "ustar" ? true: false;
-}
-
-// checks if a 512byte block consist only of 0 or \0
-bool eof (const char* buf) {
-    std::string test(&buf[0]);
-    std::erase(test, '\0');
-    std::erase(test, '0');
-    if (test.size() == 0)
-        return 1;
-    return 0;
-}
-
-// gets size of an item in bytes. assumes octal encoding.
-uint64_t getitemsize(const char* buf){
-    std::string asciisize(&buf[124], 11); // at offset 124 because first byte marks octal or base256 coding
-    uint64_t itemsize{};
-    uint8_t power = 10;
-    for (auto i : asciisize) {
-        uint8_t value = i - '0';
-        itemsize += static_cast<uint64_t >(value * std::pow(8, power));
-        power--;
-    }
-    return itemsize;
-}
-
-// gets type of an item
-std::string getitemtype(char &n) {
-    // read itemtype
-    switch (n){
-        case '0': case '\0':
-            return typeFile;
-        case '1':
-            return typeHard;
-        case '2':
-            return typeSym;
-        case '5':
-            return typeDir;
-        default:
-            return typeOther;
-    }
-}
-
-
+#include "tarconst.h"
+#include "tarfunc.h"
 
 int main(int argc, char** argv) {
 
     // GENERAL VARIABLES
     //count the types of all items
     std::map<std::string, uint> typecount{
-        {typeFile, 0}, {typeDir, 0}, {typeSym, 0},
-        {typeHard, 0}, {typeOther, 0}
+        {tarconstant::typeFile, 0}, {tarconstant::typeDir, 0}, {tarconstant::typeSym, 0},
+        {tarconstant::typeHard, 0}, {tarconstant::typeOther, 0}
     };
 
     uint64_t sizeof_allfiles{}; // total size of all files in the archive
 
-    std::string helptext
-    {"usage: tarstats-pp [-h] [-j] [-f] tarfile.\n"
-     "A tool to calculate basics statistics on tarball. Shamelessly inspired by github.com/isotopp/tarstats!\n\n"
-     "mandatory argument:\n"
-     "tarfile   a tarfile to calculate stats on\n\n"
-     "optional arguments\n"
-     "-h        this helptext\n"
-     "-j        stats in JSON format printed to stdout\n"
-     "-f        print stats to file <tarfilename>.txt or .json if -j invoked"};
-
     // Trivial check for arguments. Errorprone and has to be changed.
     if (argc < 2) {
-        std::cout << helptext << '\n';
+        std::cout << tarconstant::helptext << '\n';
         return 9;
     }
     // Getting name from argument lists on startup. Trivial and errorprone. Placeholder for now.
@@ -99,39 +34,36 @@ int main(int argc, char** argv) {
     std::ifstream file(archiveFilename, std::ios::binary);
     if(!file) {
         std::cout << "Error opening file!" << '\n' << '\n';
-        std::cout << helptext << '\n';
+        std::cout << tarconstant::helptext << '\n';
         return 9;
     }
 
-    if (!validTar(file)) {
+    if (!tar::validTar(file)) {
         std::cout << archiveFilename << " is not a valid tar file for tarstats-pp" << '\n';
         return 9;
     }
 
-    // Tar spec is working with continous 512 byte size blocks. Header is 512 bytes.
-    int buffersize = 512;
     while (file) {
-        //Read header of first item in tar archive
-        char *headbuffer = new char[buffersize];
-        file.read(headbuffer, buffersize);
+        //Read header of next item in tar archive
+        char *headbuffer = new char[tarconstant::blocksize];
+        file.read(headbuffer, tarconstant::blocksize);
 
         // tar file ends with 2 512byte blocks of 0. As no block should ever be 0 unless at the end, we check only once.
-        if (eof(headbuffer)) {
+        if (tar::eof(headbuffer)) {
             break;
         }
 
         // Read type of item
-        std::string itemtype{};
-        itemtype = getitemtype(headbuffer[156]);
+        std::string itemtype = tar::getitemtype(headbuffer[tarconstant::itemtypeByte]);
         typecount[itemtype] += 1;
 
-
         // read itemsize and add to total
-        sizeof_allfiles += getitemsize(headbuffer);
+        sizeof_allfiles += tar::getitemsize(headbuffer);
 
         // ignore file content. we want to get to the next header. item types != FILE have no content blocks (0 byte)
-        if (getitemsize(headbuffer)!=0) {
-            file.ignore((getitemsize(headbuffer) / 512) * 512 + 512);
+        if (tar::getitemsize(headbuffer)!=0) {
+            file.ignore((tar::getitemsize(headbuffer) / tarconstant::blocksize)
+                        * tarconstant::blocksize + tarconstant::blocksize);
         }
 
         // empty the headerbuffer

tarconst.h

@@ -0,0 +1,40 @@
+/* this headerfile contains global constant variables needed during parsing of a tar file
+ *
+ * by Marcel Nowicki (github@epenis.de | github.com/blindi0815)
+ */
+
+#ifndef TARSTATS___TARCONST_H
+#define TARSTATS___TARCONST_H
+
+#include <string>
+#include <utility>
+
+namespace tarconstant {
+    // global itemtype definition
+    inline std::string const typeFile = "FILES";
+    inline std::string const typeDir = "DIRECTORIES";
+    inline std::string const typeSym = "SYMLINKS";
+    inline std::string const typeHard = "HARDLINKS";
+    inline std::string const typeOther = "OTHER";
+
+    // valid magicfield
+    inline std::string const mgcfield = "ustar";
+
+    // Byte offsets
+    inline uint16_t blocksize = 512; // tar consists of continuous 512 Byte data blocks
+    inline uint8_t itemtypeByte = 156;
+    inline std::pair<uint16_t, uint8_t> mgcfieldByte {257,6};      // { offset , length }
+    inline std::pair<uint8_t , uint8_t> itemoctlnByte {124,11};    // at offset 124 because first byte
+                                                                        // marks octal or base256 coding
+    inline std::string helptext
+            {"usage: tarstats-pp [-h] [-j] [-f] tarfile.\n"
+             "A tool to calculate basics statistics on tarball. Shamelessly inspired by github.com/isotopp/tarstats!\n\n"
+             "mandatory argument:\n"
+             "tarfile   a tarfile to calculate stats on\n\n"
+             "optional arguments\n"
+             "-h        this helptext\n"
+             "-j        stats in JSON format printed to stdout\n"
+             "-f        print stats to file <tarfilename>.txt or .json if -j invoked"};
+}
+
+#endif //TARSTATS___TARCONST_H

tarfunc.cpp

@@ -0,0 +1,60 @@
+/* this file contains function definitions for parsing a tar file.
+ *
+ * by Marcel Nowicki (github@epenis.de | github.com/blindi0815)
+ */
+
+#include "tarfunc.h"
+#include "tarconst.h"
+#include <string>
+#include <cmath>
+
+// checks if a valid modern tar file - ustar
+bool tar::validTar(std::istream &file) {
+    file.seekg(tarconstant::mgcfieldByte.first);
+    char* buffer = new char [tarconstant::mgcfieldByte.second];
+    file.read(buffer, tarconstant::mgcfieldByte.second);
+    std::string magicfield(&buffer[0], 5);
+    delete[] buffer;
+    file.seekg(0);
+    return magicfield == tarconstant::mgcfield ? true: false;
+}
+
+// checks if a 512byte block consist only of 0 or \0
+bool tar::eof (const char* buf) {
+    std::string test(&buf[0]);
+    std::erase(test, '\0');
+    std::erase(test, '0');
+    if (test.empty())
+        return true;
+    return false;
+}
+
+// gets size of an item in bytes. assumes octal encoding.
+uint64_t tar::getitemsize(const char* buf){
+    std::string asciisize(&buf[tarconstant::itemoctlnByte.first], tarconstant::itemoctlnByte.second);
+    uint64_t itemsize{};
+    uint8_t power = tarconstant::itemoctlnByte.second - 1;
+    for (auto i : asciisize) {
+        uint8_t value = i - '0';
+        itemsize += static_cast<uint64_t >(value * std::pow(8, power));
+        power--;
+    }
+    return itemsize;
+}
+
+// gets type of an item
+std::string tar::getitemtype(char &n) {
+    // read itemtype
+    switch (n){
+        case '0': case '\0':
+            return tarconstant::typeFile;
+        case '1':
+            return tarconstant::typeHard;
+        case '2':
+            return tarconstant::typeSym;
+        case '5':
+            return tarconstant::typeDir;
+        default:
+            return tarconstant::typeOther;
+    }
+}

tarfunc.h

@@ -0,0 +1,26 @@
+/* this header file contains function declarations used parsing a tar file
+ *
+ * by Marcel Nowicki (github@epenis.de | github.com/blindi0815)
+ */
+
+#include <fstream>
+
+
+#ifndef TARSTATS___TARFUNC_H
+#define TARSTATS___TARFUNC_H
+namespace tar {
+// checks if a valid modern tar file - ustar
+    bool validTar(std::istream &file);
+
+// checks if a 512byte block consist only of 0 or \0
+    bool eof(const char *buf);
+
+// gets size of an item in bytes. assumes octal encoding.
+    uint64_t getitemsize(const char *buf);
+
+// gets type of an item
+    std::string getitemtype(char &n);
+}
+
+
+#endif //TARSTATS___TARFUNC_H