DrKLO/Telegram · error

Invalid JPEG quality value!\n

Error message

Invalid JPEG quality value!\n

What it means

yuvjpeg parses argv[1] as the JPEG quality via strtol. If errno is non-zero after the conversion (overflow/no-digits) OR the value is < 0 or > 100, it prints `Invalid JPEG quality value!` and returns 1. This guards the libjpeg quality parameter, which only has defined behaviour in [0,100].

Source

Thrown at TMessagesProj/jni/mozjpeg/yuvjpeg.c:129

  JSAMPROW cbrow_pointer[8];
  JSAMPROW crrow_pointer[8];
  JSAMPROW *plane_pointer[3];
  int y;

  if (argc != 5) {
    fprintf(stderr, "Required arguments:\n");
    fprintf(stderr, "1. JPEG quality value, 0-100\n");
    fprintf(stderr, "2. Image size (e.g. '512x512')\n");
    fprintf(stderr, "3. Path to YUV input file\n");
    fprintf(stderr, "4. Path to JPG output file\n");
    return 1;
  }

  errno = 0;

  quality = strtol(argv[1], NULL, 10);
  if (errno != 0 || quality < 0 || quality > 100) {
    fprintf(stderr, "Invalid JPEG quality value!\n");
    return 1;
  }

  matches = sscanf(argv[2], "%dx%d", &luma_width, &luma_height);
  if (matches != 2) {
    fprintf(stderr, "Invalid image size input!\n");
    return 1;
  }
  if (luma_width <= 0 || luma_height <= 0) {
    fprintf(stderr, "Invalid image size input!\n");
    return 1;
  }

  chroma_width = (luma_width + 1) >> 1;
  chroma_height = (luma_height + 1) >> 1;

  /* Will check these for validity when opening via 'fopen'. */
  yuv_path = argv[3];

View on GitHub (pinned to 45ab8f4308)

Solutions

  1. Pass an integer quality strictly in [0,100].
  2. Clamp the value in the caller: q = max(0, min(100, q)).
  3. Validate argv[1] matches ^[0-9]{1,3}$ and is <= 100 before invoking.

Example fix

// before
yuvjpeg 120 512x512 in.yuv out.jpg
// after
yuvjpeg 100 512x512 in.yuv out.jpg
Defensive patterns

Strategy: validation

Validate before calling

#include <errno.h>
#include <stdlib.h>
errno = 0;
long q = strtol(argv[1], NULL, 10);
if (errno != 0 || q < 0 || q > 100) { /* reject; do not invoke yuvjpeg */ }

Prevention

When it happens

Trigger: Invoking `yuvjpeg <q> ...` where <q> is non-numeric, empty, out of integer range (ERANGE), or numerically outside 0-100 (e.g. 120 or -5).

Common situations: Passing a float like 90.5 (strtol stops at '.', may parse 90 but is suspect), a percentage sign like '90%', a blank argument, or a value over 100 from a misconfigured UI slider.

Related errors

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/e37ee52575c36c34. Report an issue: GitHub.