image.h File Reference

🖼️ Safe overflow-checked buffer size calculations for images and video frames More...

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Functions
asciichat_error_t	image_calc_pixel_count (size_t width, size_t height, size_t *out_pixel_count)
	Calculate pixel count with overflow checking.
asciichat_error_t	image_calc_pixel_buffer_size (size_t pixel_count, size_t bytes_per_pixel, size_t *out_size)
	Calculate pixel buffer size with overflow checking.
asciichat_error_t	image_calc_rgb_size (size_t width, size_t height, size_t *out_size)
	Calculate total RGB buffer size from dimensions.
asciichat_error_t	image_calc_total_allocation (size_t width, size_t height, size_t struct_size, size_t bytes_per_pixel, size_t *out_size)
	Calculate combined size of image struct + pixel buffer.
asciichat_error_t	image_validate_dimensions (size_t width, size_t height)
	Validate image dimensions (non-zero, within limits)
asciichat_error_t	image_validate_buffer_size (size_t requested_size)
	Validate buffer size against maximum allocation limit.

Detailed Description

🖼️ Safe overflow-checked buffer size calculations for images and video frames

Provides helpers for calculating buffer sizes with proper overflow detection. All functions return error codes and set errno for detailed error context.

Definition in file util/image.h.

Function Documentation

image_calc_pixel_buffer_size()

asciichat_error_t image_calc_pixel_buffer_size	(	size_t	pixel_count,
		size_t	bytes_per_pixel,
		size_t *	out_size
	)

Calculate pixel buffer size with overflow checking.

Parameters

pixel_count	Number of pixels
bytes_per_pixel	Size of each pixel (e.g., 3 for RGB, 4 for RGBA)
out_size	Output: calculated buffer size in bytes

Returns

ASCIICHAT_OK on success, ERROR_INVALID_PARAM on overflow

Safe wrapper for: size = pixel_count * bytes_per_pixel Prevents integer overflow by checking before multiplication

Definition at line 31 of file util/image.c.

                                                                                                             {
  if (!out_size) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "out_size is NULL");
  }
 
  if (pixel_count == 0) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Pixel count must be non-zero");
  }
 
  if (bytes_per_pixel == 0) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "bytes_per_pixel must be non-zero");
  }
 
  // Check overflow before multiplication
  if (pixel_count > SIZE_MAX / bytes_per_pixel) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Pixel buffer too large (would overflow): %zu pixels * %zu bpp", pixel_count,
                     bytes_per_pixel);
  }
 
  *out_size = pixel_count * bytes_per_pixel;
  return ASCIICHAT_OK;
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, and SET_ERRNO.

Referenced by image_calc_rgb_size(), and image_calc_total_allocation().

image_calc_pixel_count()

asciichat_error_t image_calc_pixel_count	(	size_t	width,
		size_t	height,
		size_t *	out_pixel_count
	)

Calculate pixel count with overflow checking.

Parameters

width	Image width (pixels)
height	Image height (pixels)
out_pixel_count	Output: calculated pixel count

Returns

ASCIICHAT_OK on success, ERROR_INVALID_PARAM on overflow

Safe wrapper for: pixel_count = width * height Prevents integer overflow by checking before multiplication

Definition at line 12 of file util/image.c.

                                                                                               {
  if (!out_pixel_count) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "out_pixel_count is NULL");
  }
 
  // Check for zero dimensions
  if (width == 0 || height == 0) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Image dimensions must be non-zero: %zu x %zu", width, height);
  }
 
  // Check overflow before multiplication
  if (height > SIZE_MAX / width) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Image dimensions too large (would overflow): %zu x %zu", width, height);
  }
 
  *out_pixel_count = width * height;
  return ASCIICHAT_OK;
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, and SET_ERRNO.

Referenced by image_calc_rgb_size(), and image_calc_total_allocation().

image_calc_rgb_size()

asciichat_error_t image_calc_rgb_size	(	size_t	width,
		size_t	height,
		size_t *	out_size
	)

Calculate total RGB buffer size from dimensions.

Parameters

width	Image width (pixels)
height	Image height (pixels)
out_size	Output: total buffer size (width * height * 3 bytes)

Returns

ASCIICHAT_OK on success, ERROR_INVALID_PARAM on overflow

Convenience function for RGB images (3 bytes per pixel). Safe wrapper for: size = width * height * 3

Definition at line 54 of file util/image.c.

                                                                                     {
  if (!out_size) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "out_size is NULL");
  }
 
  // Calculate pixel count first
  size_t pixel_count;
  asciichat_error_t err = image_calc_pixel_count(width, height, &pixel_count);
  if (err != ASCIICHAT_OK) {
    return err;
  }
 
  // Calculate size with 3 bytes per pixel (RGB)
  return image_calc_pixel_buffer_size(pixel_count, 3, out_size);
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, image_calc_pixel_buffer_size(), image_calc_pixel_count(), and SET_ERRNO.

Referenced by handle_image_frame_packet().

image_calc_total_allocation()

asciichat_error_t image_calc_total_allocation	(	size_t	width,
		size_t	height,
		size_t	struct_size,
		size_t	bytes_per_pixel,
		size_t *	out_size
	)

Calculate combined size of image struct + pixel buffer.

Parameters

width	Image width (pixels)
height	Image height (pixels)
struct_size	Size of image_t structure (typically sizeof(image_t))
bytes_per_pixel	Size of each pixel
out_size	Output: total allocation size

Returns

ASCIICHAT_OK on success, ERROR_INVALID_PARAM on overflow

Used for pool allocations where struct and pixels are contiguous. Safe calculation of: struct_size + (width * height * bytes_per_pixel)

Definition at line 70 of file util/image.c.

                                                                {
  if (!out_size) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "out_size is NULL");
  }
 
  // Calculate pixel count first with overflow checking
  size_t pixel_count;
  asciichat_error_t err = image_calc_pixel_count(width, height, &pixel_count);
  if (err != ASCIICHAT_OK) {
    return err;
  }
 
  // Calculate pixel buffer size
  size_t pixel_buffer_size;
  err = image_calc_pixel_buffer_size(pixel_count, bytes_per_pixel, &pixel_buffer_size);
  if (err != ASCIICHAT_OK) {
    return err;
  }
 
  // Check overflow when adding struct size
  if (pixel_buffer_size > SIZE_MAX - struct_size) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Total allocation size would overflow: struct=%zu + pixels=%zu", struct_size,
                     pixel_buffer_size);
  }
 
  *out_size = struct_size + pixel_buffer_size;
  return ASCIICHAT_OK;
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, image_calc_pixel_buffer_size(), image_calc_pixel_count(), and SET_ERRNO.

image_validate_buffer_size()

asciichat_error_t image_validate_buffer_size

(

size_t

requested_size

)

Validate buffer size against maximum allocation limit.

Parameters

requested_size

Requested buffer size

Returns

ASCIICHAT_OK if valid, ERROR_INVALID_PARAM if exceeds maximum

Checks that requested_size <= IMAGE_MAX_PIXELS_SIZE Sets errno with detailed context if validation fails

Definition at line 115 of file util/image.c.

                                                                    {
  if (requested_size > IMAGE_MAX_PIXELS_SIZE) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Image buffer size exceeds maximum: %zu > %zu bytes", requested_size,
                     IMAGE_MAX_PIXELS_SIZE);
  }
 
  return ASCIICHAT_OK;
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, IMAGE_MAX_PIXELS_SIZE, and SET_ERRNO.

Referenced by handle_image_frame_packet().

image_validate_dimensions()

asciichat_error_t image_validate_dimensions	(	size_t	width,
		size_t	height
	)

Validate image dimensions (non-zero, within limits)

Parameters

width	Image width to validate
height	Image height to validate

Returns

ASCIICHAT_OK if valid, ERROR_INVALID_PARAM if invalid

Checks that:

• Both width and height are non-zero
• Dimensions don't exceed IMAGE_MAX_WIDTH and IMAGE_MAX_HEIGHT Sets errno with detailed context if validation fails

Definition at line 12 of file video.c.

                                                                         {
  if (width > 0 && height > 0 && width <= 10000 && height <= 10000) {
    return ASCIICHAT_OK;
  }
  return ERROR_INVALID_PARAM;
}

References ASCIICHAT_OK, ERROR_INVALID_PARAM, IMAGE_MAX_HEIGHT, IMAGE_MAX_WIDTH, and SET_ERRNO.

Referenced by handle_image_frame_packet(), and image_new().