r/utils.h

// Written by retoor@molodetz.nl

// This header file contains utility functions for manipulating file system paths, focusing primarily on expanding paths starting with '~' to the home directory.

// This code uses standard libraries: stdio.h, stdlib.h, and string.h, and conditionally includes the posix libraries pwd.h and unistd.h when expanding the home directory manually.

// MIT License
//
// Permission is granted to use, copy, modify, merge, distribute, sublicense, and/or sell copies of the Software.
// The license includes conditions about providing a copy of the license and the limitation of liability and warranty.

#ifndef UTILS_H
#define UTILS_H

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* expand_home_directory(const char* path) {
    if (path == NULL) return NULL;

    if (path[0] == '~' && path[1] == '/') {
        const char* home_dir = getenv("HOME");
        if (home_dir == NULL) {
            #include <pwd.h>
            #include <unistd.h>
            struct passwd* pw = getpwuid(getuid());
            if (pw == NULL) return NULL;
            home_dir = pw->pw_dir;
        }

        size_t home_len = strlen(home_dir);
        size_t path_len = strlen(path) - 1;
        char* expanded_path = malloc(home_len + path_len + 1);

        if (expanded_path == NULL) return NULL;

        strcpy(expanded_path, home_dir);
        strcat(expanded_path, path + 1);

        return expanded_path;
    } else {
        return strdup(path);
    }
}
char * read_file(const char * path) {
    char * expanded_path = expand_home_directory(path);
    FILE *file = fopen(expanded_path, "r");
    free(expanded_path);
    if (file == NULL) {
        return NULL;
    }
    fseek(file, 0, SEEK_END);
    long size = ftell(file);
    fseek(file, 0, SEEK_SET);

    char *buffer = (char *)malloc(size + 1);
    size_t read = fread(buffer, 1, size, file);
    if (read == 0) {
        free(buffer);
        return NULL;
    }

    fclose(file);
    buffer[read] = '\0';
    return buffer;
}
#endif