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