auth_service_c/src/file.c

#include "file.h"

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

char *read_file(const char *path) {
  create_file_if_not_exists(path);
  FILE *fp = fopen(path, "rb");
  if (fp == NULL) {
    perror("Error opening file");
    return nullptr;
  }

  fseek(fp, 0, SEEK_END);
  long file_size = ftell(fp);
  rewind(fp);

  char *buffer = (char *) malloc(file_size + 1);
  if (!buffer) {
    perror("Error allocating memory");
    fclose(fp);
    return nullptr;
  }

  size_t bytes_read = fread(buffer, 1, file_size, fp);
  if (bytes_read != file_size) {
    perror("Error reading file");
    free(buffer);
    fclose(fp);
    return nullptr;
  }

  buffer[file_size] = '\0';
  fclose(fp);
  return buffer;
}

char *write_file(const char *path, const char *data) {
  create_file_if_not_exists(path);
  FILE *fp = fopen(path, "w");
  if (fp == NULL) {
    printf("%s\n", path);
    perror("Error opening file");
    return nullptr;
  }
  if (fprintf(fp, "%s", data) < 0) {
    perror("Error write file");
    return nullptr;
  }
  fclose(fp);
  char *ret = strdup(data);
  return ret;
}

int create_file_if_not_exists(const char *filename) {
  if (!check_file_exists(filename)) {
    return 0;
  }
  FILE *file = fopen(filename, "w");
  if (file == nullptr) {
    perror("Error creating file");
    return -1;
  }
  fclose(file);
  return 0;
}

int check_file_exists(const char *filename) {
  if (access(filename, F_OK) == 0) {
    return 0;
  }
  return -1;
}