Initial project structure. (#1)

src/util/util.cpp

@@ -0,0 +1,100 @@
+#include "../pchheader.hpp"
+#include "util.hpp"
+
+namespace util
+{
+    /**
+     * Check whether given directory exists. 
+     * @param path Directory path.
+     * @return Returns true if given directory exists otherwise false.
+     */
+    bool is_dir_exists(std::string_view path)
+    {
+        struct stat st;
+        return (stat(path.data(), &st) == 0 && S_ISDIR(st.st_mode));
+    }
+
+    /**
+     * Check whether given file exists. 
+     * @param path File path.
+     * @return Returns true if give file exists otherwise false.
+     */
+    bool is_file_exists(std::string_view path)
+    {
+        struct stat st;
+        return (stat(path.data(), &st) == 0 && S_ISREG(st.st_mode));
+    }
+
+    /**
+     * Recursively creates directories and sub-directories if not exist. 
+     * @param path Directory path.
+     * @return Returns 0 operations succeeded otherwise -1.
+     */
+    int create_dir_tree_recursive(std::string_view path)
+    {
+        if (strcmp(path.data(), "/") == 0) // No need of checking if we are at root.
+            return 0;
+
+        // Check whether this dir exists or not.
+        struct stat st;
+        if (stat(path.data(), &st) != 0 || !S_ISDIR(st.st_mode))
+        {
+            // Check and create parent dir tree first.
+            char *path2 = strdup(path.data());
+            char *parent_dir_path = dirname(path2);
+            bool error_thrown = false;
+
+            if (create_dir_tree_recursive(parent_dir_path) == -1)
+                error_thrown = true;
+
+            free(path2);
+
+            // Create this dir.
+            if (!error_thrown && mkdir(path.data(), S_IRWXU | S_IRWXG | S_IROTH) == -1)
+            {
+                std::cerr << errno << ": Error in recursive dir creation. " << path << std::endl;
+                error_thrown = true;
+            }
+
+            if (error_thrown)
+                return -1;
+        }
+
+        return 0;
+    }
+
+    /**
+     * Reads the entire file from given file discriptor. 
+     * @param fd File descriptor to be read.
+     * @param buf String buffer to be populated.
+     * @param offset Begin offset of the file to read.
+     * @return Returns number of bytes read in a successful read and -1 on error.
+    */
+    int read_from_fd(const int fd, std::string &buf, const off_t offset)
+    {
+        struct stat st;
+        if (fstat(fd, &st) == -1)
+        {
+            std::cerr << errno << ": Error in stat for reading entire file." << std::endl;
+            return -1;
+        }
+
+        buf.resize(st.st_size - offset);
+
+        return pread(fd, buf.data(), buf.size(), offset);
+    }
+
+    /**
+     * Provide a safe std::string overload for realpath.
+     * @param path Path.
+     * @returns Returns the realpath as string.
+    */
+    const std::string realpath(std::string_view path)
+    {
+        std::array<char, PATH_MAX> buffer;
+        ::realpath(path.data(), buffer.data());
+        buffer[PATH_MAX] = '\0';
+        return buffer.data();
+    }
+
+} // namespace util