path: root/src/libdisfluid/disfluid-cache-entry.h

#ifndef DISFLUID_DISFLUID_CACHE_ENTRY_INCLUDED
# define DISFLUID_DISFLUID_CACHE_ENTRY_INCLUDED

MAYBE_UNUSED static struct disfluid_cache_entry *cache_entry_alloc (void);

MAYBE_UNUSED static void
cache_entry_free (struct disfluid_cache_entry *entry);

MAYBE_UNUSED static struct disfluid_cache_entry
  *cache_entry_from_file_name (const char *file_name);

MAYBE_UNUSED static struct disfluid_cache_entry *cache_entry_from_fd (int fd);

MAYBE_UNUSED static struct disfluid_cache_entry
  *cache_entry_dup (const struct disfluid_cache_entry *entry);

MAYBE_UNUSED static int
cache_entry_save_other_file_name (const struct disfluid_cache_entry *entry,
				  const char *file_name);

MAYBE_UNUSED static int
cache_entry_save_other_fd (const struct disfluid_cache_entry *entry, int fd);

MAYBE_UNUSED static void
cache_entry_set_request_date (struct disfluid_cache_entry *entry,
			      const struct timespec *date);

MAYBE_UNUSED static void
cache_entry_set_response_date (struct disfluid_cache_entry *entry,
			       const struct timespec *date);

MAYBE_UNUSED static void
cache_entry_invalidate (struct disfluid_cache_entry *entry);

MAYBE_UNUSED static void
cache_entry_set_invalidated (struct disfluid_cache_entry *entry,
			     bool invalidated);

MAYBE_UNUSED static void
cache_entry_set_file_name (struct disfluid_cache_entry *entry,
			   const char *file_name);

MAYBE_UNUSED static void
cache_entry_get_request_date (const struct disfluid_cache_entry *entry,
			      struct timespec *date);

MAYBE_UNUSED static void
cache_entry_get_response_date (const struct disfluid_cache_entry *entry,
			       struct timespec *date);

MAYBE_UNUSED static bool
cache_entry_invalidated (const struct disfluid_cache_entry *entry);

MAYBE_UNUSED static char *cache_entry_get_file_name (const struct
						     disfluid_cache_entry
						     *entry);

# include <assert.h>

# include "disfluid-init.h"

struct disfluid_cache_entry
{
  char *file_name;		/* Might be NULL */
  int fd;			/* Might be < 0, but must be >= 0 if there is a file_name. */
  off_t start;
  off_t header_stop;
  struct timespec request_date;
  struct timespec response_date;
  bool invalidated;
};

static struct disfluid_cache_entry *
cache_entry_alloc (void)
{
  ensure_init ();
  struct disfluid_cache_entry *ret =
    malloc (sizeof (struct disfluid_cache_entry));
  if (ret == NULL)
    {
      abort ();
    }
  ret->file_name = NULL;
  ret->fd = -1;
  ret->start = 0;
  ret->header_stop = 0;
  ret->request_date.tv_sec = 0;
  ret->request_date.tv_nsec = 0;
  ret->response_date.tv_sec = 0;
  ret->response_date.tv_nsec = 0;
  ret->invalidated = false;
  return ret;
}

static void
cache_entry_free (struct disfluid_cache_entry *entry)
{
  if (entry != NULL)
    {
      free (entry->file_name);
      if (entry->fd >= 0)
	{
	  close (entry->fd);
	}
    }
  free (entry);
}

static struct disfluid_cache_entry *
cache_entry_from_file_name (const char *file_name)
{
  int fd = open (file_name, O_RDONLY, S_IRUSR);
  if (fd < 0)
    {
      abort ();
    }
  struct disfluid_cache_entry *ret = cache_entry_from_fd (fd);
  if (ret == NULL)
    {
      abort ();
    }
  cache_entry_set_file_name (ret, file_name);
  return ret;
}

static struct disfluid_cache_entry *
cache_entry_dup (const struct disfluid_cache_entry *entry)
{
  struct disfluid_cache_entry *ret = cache_entry_alloc ();
  if (ret != NULL && entry->fd >= 0)
    {
      ret->fd = dup (entry->fd);
      if (ret->fd < 0)
	{
	  cache_entry_free (ret);
	  ret = NULL;
	}
    }
  if (ret != NULL && entry->file_name != NULL)
    {
      ret->file_name = strdup (entry->file_name);
      if ((ret->file_name == NULL) != (entry->file_name == NULL))
	{
	  cache_entry_free (ret);
	  ret = NULL;
	}
    }
  if (ret != NULL)
    {
      ret->start = entry->start;
      ret->header_stop = entry->header_stop;
      ret->request_date.tv_sec = entry->request_date.tv_sec;
      ret->request_date.tv_nsec = entry->request_date.tv_nsec;
      ret->response_date.tv_sec = entry->response_date.tv_sec;
      ret->response_date.tv_nsec = entry->response_date.tv_nsec;
      ret->invalidated = entry->invalidated;
    }
  return ret;
}

static inline void
cache_entry_string_append (char **str, size_t *max, size_t *n,
			   size_t suffix_length, const char *suffix)
{
  if (*n + suffix_length > *max)
    {
      *str = realloc (*str, 2 * *max);
      if (*str == NULL)
	{
	  abort ();
	}
      *max *= 2;
      cache_entry_string_append (str, max, n, suffix_length, suffix);
    }
  else
    {
      memcpy (&((*str)[*n]), suffix, suffix_length);
      *n += suffix_length;
    }
}

static inline ssize_t
cache_entry_read_next_line_aux (int fd, size_t *restrict buffer_max,
				size_t *restrict buffer_length, char **buffer,
				size_t checked)
{
  while (checked + 1 < *buffer_length
	 && ((*buffer)[checked] != '\r' || (*buffer)[checked + 1] != '\n'))
    {
      checked++;
    }
  if (checked + 1 < *buffer_length)
    {
      return checked + 2;
    }
  if (*buffer_length == *buffer_max)
    {
      *buffer = realloc (*buffer, 2 * *buffer_max);
      if (*buffer == NULL)
	{
	  abort ();
	}
      *buffer_max *= 2;
    }
  assert (*buffer_max > *buffer_length);
  ssize_t n_added =
    read (fd, &((*buffer)[*buffer_length]), *buffer_max - *buffer_length);
  if (n_added < 0)
    {
      abort ();
    }
  else if (n_added == 0)
    {
      return *buffer_length;
    }
  else
    {
      assert (*buffer_length + n_added <= *buffer_max);
      *buffer_length += n_added;
    }
  return cache_entry_read_next_line_aux (fd, buffer_max, buffer_length,
					 buffer, checked);
}

static inline void
cache_entry_read_next_line (int fd, size_t *restrict buffer_max,
			    size_t *restrict buffer_length, char **buffer,
			    char **line, size_t *line_length)
{
  ssize_t length =
    cache_entry_read_next_line_aux (fd, buffer_max, buffer_length, buffer, 0);
  if (length < 0)
    {
      abort ();
    }
  *line = malloc (length + 1);
  if (*line == NULL)
    {
      abort ();
    }
  *line_length = length;
  memcpy (*line, *buffer, length);
  (*line)[length] = '\0';
  memmove (*buffer, &((*buffer)[length]), *buffer_length - length);
  *buffer_length -= length;
}

static inline void
cache_entry_enumerate_header_lines (const struct disfluid_cache_entry *entry,
				    void (*cb) (void *, const char *,
						const char *), void *context)
{
  off_t start_offset = lseek (entry->fd, 0, SEEK_CUR);
  if (start_offset < 0)
    {
      abort ();
    }
  size_t buffer_max = 1;
  size_t buffer_length = 0;
  char *buffer = malloc (buffer_max);
  if (buffer == NULL)
    {
      abort ();
    }
  char *line;
  size_t line_length;
  while (true)
    {
      cache_entry_read_next_line (entry->fd, &buffer_max, &buffer_length,
				  &buffer, &line, &line_length);
      if (line == NULL)
	{
	  /* Memory error */
	  abort ();
	}
      if (STREQ (line, "\r\n"))
	{
	  /* End of parse */
	  ssize_t undo = buffer_length;
	  lseek (entry->fd, -undo, SEEK_CUR);
	  free (buffer);
	  free (line);
	  return;
	}
      char *header_name = malloc (line_length + 1);
      if (header_name == NULL)
	{
	  abort ();
	}
      size_t header_name_length = 0;
      for (header_name_length = 0;
	   header_name_length < line_length
	   && line[header_name_length] != ':'; header_name_length++)
	{
	  if (line[header_name_length] >= 'A'
	      && line[header_name_length] <= 'Z')
	    {
	      line[header_name_length] =
		(line[header_name_length] - 'A') + 'a';
	    }
	  header_name[header_name_length] = line[header_name_length];
	}
      header_name[header_name_length] = '\0';
      if (line[header_name_length] != ':')
	{
	  /* HTTP bad header, restore position */
	  lseek (entry->fd, start_offset, SEEK_SET);
	  free (buffer);
	  free (line);
	  free (header_name);
	  return;
	}
      header_name_length++;
      cb (context, header_name, &(line[header_name_length]));
      free (line);
      free (header_name);
    }
}

static inline void
cache_entry_parse_timespec (const char *data, struct timespec *ts)
{
  /* A timespec is represented as SSS.NNN where SSS is the number of seconds, and NNN the number of nanoseconds. */
  while (*data == ' ' || *data == '\t' || *data == '\r' || *data == '\n')
    {
      data++;
    }
  struct timespec r = {.tv_sec = 0,.tv_nsec = 0 };
  size_t n_seconds_digits = 0;
  for (n_seconds_digits = 0;
       data[n_seconds_digits] >= '0' && data[n_seconds_digits] <= '9';
       n_seconds_digits++)
    {
      r.tv_sec *= 10;
      r.tv_sec += (data[n_seconds_digits] - '0');
    }
  data += n_seconds_digits;
  const bool has_dot = (data[0] == '.');
  if (has_dot)
    {
      data++;
    }
  int nano_digits[9] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
  for (size_t i = 0; i < 9 && data[i] >= '0' && data[i] <= '9'; i++)
    {
      nano_digits[i] = (data[i] - '0');
    }
  for (size_t i = 0; i < 9; i++)
    {
      r.tv_nsec *= 10;
      r.tv_nsec += nano_digits[i];
    }
  ts->tv_sec = r.tv_sec;
  ts->tv_nsec = r.tv_nsec;
}

static inline void
cache_entry_iterate_metadata (void *ctx, const char *header,
			      const char *value)
{
  struct disfluid_cache_entry *entry = ctx;
  if (STREQ (header, "request-date"))
    {
      cache_entry_parse_timespec (value, &(entry->request_date));
    }
  else if (STREQ (header, "response-date"))
    {
      cache_entry_parse_timespec (value, &(entry->response_date));
    }
  else if (STREQ (header, "invalidated"))
    {
      while (*value == ' ' || *value == '\t' || *value == '\r'
	     || *value == '\n')
	{
	  value++;
	}
      if (STREQ (value, "true\r\n"))
	{
	  entry->invalidated = true;
	}
      else if (STREQ (value, "false\r\n"))
	{
	  entry->invalidated = false;
	}
    }
}

static inline void
cache_entry_scan (struct disfluid_cache_entry *entry)
{
  entry->start = lseek (entry->fd, 0, SEEK_CUR);
  cache_entry_enumerate_header_lines (entry, cache_entry_iterate_metadata,
				      entry);
  entry->header_stop = lseek (entry->fd, 0, SEEK_CUR);
  /* Reset the file descriptor position, in case it is shared */
  lseek (entry->fd, entry->start, SEEK_SET);
}

static struct disfluid_cache_entry *
cache_entry_from_fd (int fd)
{
  struct disfluid_cache_entry *ret = cache_entry_alloc ();
  if (ret == NULL)
    {
      abort ();
    }
  ret->fd = dup (fd);
  if (ret->fd < 0)
    {
      abort ();
    }
  cache_entry_scan (ret);
  assert (ret->start >= 0);
  assert (ret->header_stop >= 0);
  if (ret->header_stop == ret->start)
    {
      /* Assume that reading failed. */
      cache_entry_free (ret);
      ret = NULL;
    }
  return ret;
}

static int
cache_entry_save_other_file_name (const struct disfluid_cache_entry *entry,
				  const char *file_name)
{
  int fd = open (file_name, O_WRONLY | O_CREAT | O_TRUNC,
		 S_IRUSR | S_IWUSR | S_IRGRP);
  if (fd < 0)
    {
      return errno;
    }
  return cache_entry_save_other_fd (entry, fd);
}

static int
cache_entry_save_other_fd (const struct disfluid_cache_entry *entry, int fd)
{
  char *set_request_date;
  char *set_response_date;
  char *set_invalidated;
  char *meta_header;
  int status;
  status =
    asprintf (&set_request_date, "Request-Date: %lld.%09ld\r\n",
	      (long long) entry->request_date.tv_sec,
	      (long) entry->request_date.tv_nsec);
  if (status < 0)
    {
      abort ();
    }
  status =
    asprintf (&set_response_date, "Response-Date: %lld.%09ld\r\n",
	      (long long) entry->response_date.tv_sec,
	      (long) entry->response_date.tv_nsec);
  if (status < 0)
    {
      abort ();
    }
  if (entry->invalidated)
    {
      status = asprintf (&set_invalidated, "Invalidated: true\r\n");
      if (status < 0)
	{
	  abort ();
	}
    }
  else
    {
      set_invalidated = strdup ("");
      if (set_invalidated == NULL)
	{
	  abort ();
	}
    }
  status =
    asprintf (&meta_header, "%s%s%s\r\n", set_request_date, set_response_date,
	      set_invalidated);
  free (set_request_date);
  free (set_response_date);
  free (set_invalidated);
  if (status < 0)
    {
      abort ();
    }
  size_t n_written = 0;
  while (n_written < strlen (meta_header))
    {
      ssize_t n_written_this_time = write (fd, &(meta_header[n_written]),
					   strlen (meta_header) - n_written);
      if (n_written_this_time <= 0)
	{
	  free (meta_header);
	  return 2;
	}
      n_written += n_written_this_time;
    }
  free (meta_header);
  return 0;
}

static void
cache_entry_set_request_date (struct disfluid_cache_entry *entry,
			      const struct timespec *date)
{
  entry->request_date.tv_sec = date->tv_sec;
  entry->request_date.tv_nsec = date->tv_nsec;
}

static void
cache_entry_set_response_date (struct disfluid_cache_entry *entry,
			       const struct timespec *date)
{
  entry->response_date.tv_sec = date->tv_sec;
  entry->response_date.tv_nsec = date->tv_nsec;
}

static void
cache_entry_invalidate (struct disfluid_cache_entry *entry)
{
  cache_entry_set_invalidated (entry, true);
}

static void
cache_entry_set_invalidated (struct disfluid_cache_entry *entry,
			     bool invalidated)
{
  entry->invalidated = invalidated;
}

static void
cache_entry_set_file_name (struct disfluid_cache_entry *entry,
			   const char *file_name)
{
  free (entry->file_name);
  entry->file_name = NULL;
  if (file_name != NULL)
    {
      entry->file_name = strdup (file_name);
      if (entry->file_name == NULL)
	{
	  abort ();
	}
    }
}

static void
cache_entry_get_request_date (const struct disfluid_cache_entry *entry,
			      struct timespec *date)
{
  date->tv_sec = entry->request_date.tv_sec;
  date->tv_nsec = entry->request_date.tv_nsec;
}

static void
cache_entry_get_response_date (const struct disfluid_cache_entry *entry,
			       struct timespec *date)
{
  date->tv_sec = entry->response_date.tv_sec;
  date->tv_nsec = entry->response_date.tv_nsec;
}

static bool
cache_entry_invalidated (const struct disfluid_cache_entry *entry)
{
  return entry->invalidated;
}

static char *
cache_entry_get_file_name (const struct disfluid_cache_entry *entry)
{
  if (entry->file_name == NULL)
    {
      return NULL;
    }
  char *ret = strdup (entry->file_name);
  if (ret == NULL)
    {
      abort ();
    }
  return ret;
}

#endif /* DISFLUID_DISFLUID_CACHE_ENTRY_INCLUDED */