DrKLO/Telegram · error

%s: can't open %s\n

Error message

%s: can't open %s\n

What it means

After switch parsing, wrjpgcom opens the input JPEG. If a positional file name was supplied (argn < argc) but fopen(argv[argn], READ_BINARY) fails, it prints `%s: can't open %s` (progname, path) and exits EXIT_FAILURE. This is an input-image open failure, distinct from the -cfile open failure at line 437.

Source

Thrown at TMessagesProj/jni/mozjpeg/wrjpgcom.c:495

      }
      comment_length = (unsigned int)strlen(comment_arg);
    } else
      usage();
  }

  /* Cannot use both -comment and -cfile. */
  if (comment_arg != NULL && comment_file != NULL)
    usage();
  /* If there is neither -comment nor -cfile, we will read the comment text
   * from stdin; in this case there MUST be an input JPEG file name.
   */
  if (comment_arg == NULL && comment_file == NULL && argn >= argc)
    usage();

  /* Open the input file. */
  if (argn < argc) {
    if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
      exit(EXIT_FAILURE);
    }
  } else {
    /* default input file is stdin */
#ifdef USE_SETMODE              /* need to hack file mode? */
    setmode(fileno(stdin), O_BINARY);
#endif
#ifdef USE_FDOPEN               /* need to re-open in binary mode? */
    if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open stdin\n", progname);
      exit(EXIT_FAILURE);
    }
#else
    infile = stdin;
#endif
  }

  /* Open the output file. */

View on GitHub (pinned to 45ab8f4308)

Solutions

1. Confirm the input JPEG path exists and is readable (`test -r`).
2. Quote paths containing spaces so they reach argv as one token.
3. Use an absolute path to avoid cwd mismatch.
4. Ensure the file is a valid readable JPEG, not a truncated/zero-byte file.

Example fix

// before
wrjpgcom -cfile c.txt my photo.jpg
// after
wrjpgcom -cfile c.txt "my photo.jpg"

#include <unistd.h>
/* verify input JPEG is readable before launching wrjpgcom */
if (access(input_jpg, R_OK) != 0) { /* report and abort */ }

When it happens

Trigger: Running `wrjpgcom [opts] <input.jpg>` where <input.jpg> is missing, unreadable, not a regular file, or not a JPEG at all (open still succeeds for non-JPEG; this specific message is only the open failure).

Common situations: Wrong input path/extension typo, file deleted between parse and open, permission denied, or a path with spaces passed unquoted so argv splits incorrectly.

Related errors

• %s: can't open %s
• Comment text may not exceed %u bytes
• %s: must name one input and one output file\n
• %s: only one input file\n
• Comment text may not exceed %u bytes\n

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/ad9455ed2bf959a3. Report an issue: GitHub.