cjpeg: Don't enable lossless until precision known

jpeg_enable_lossless() checks the point transform value against the data
precision, so we need to defer calling jpeg_enable_lossless() until
after all command-line options have been parsed.

ChangeLog.md

@@ -19,6 +19,11 @@ prefetching caused a segfault if the `fill_input_buffer()` method in the
 calling application's custom source manager incorrectly returned `FALSE` in
 response to a prematurely-terminated JPEG data stream.
 
+3. Fixed an issue in cjpeg whereby, when generating a 12-bit-per-sample or
+16-bit-per-sample lossless JPEG image, specifying a point transform value
+greater than 7 resulted in an error ("Invalid progressive/lossless parameters")
+unless the `-precision` option was specified before the `-lossless` option.
+
 
 3.0.3
 =====

cjpeg.c

@@ -290,7 +290,7 @@ parse_switches(j_compress_ptr cinfo, int argc, char **argv,
   int argn;
   char *arg;
 #ifdef C_LOSSLESS_SUPPORTED
-  int psv, pt = 0;
+  int psv = 0, pt = 0;
 #endif
   boolean force_baseline;
   boolean simple_progressive;
@@ -403,7 +403,8 @@ parse_switches(j_compress_ptr cinfo, int argc, char **argv,
                                         string */
       if (*ptr)
         sscanf(ptr, "%d", &pt);
-      jpeg_enable_lossless(cinfo, psv, pt);
+
+      /* We must postpone execution until data_precision is known. */
 #else
       fprintf(stderr, "%s: sorry, lossless output was not compiled\n",
               progname);
@@ -589,6 +590,11 @@ parse_switches(j_compress_ptr cinfo, int argc, char **argv,
       jpeg_simple_progression(cinfo);
 #endif
 
+#ifdef C_LOSSLESS_SUPPORTED
+    if (psv != 0)               /* process -lossless */
+      jpeg_enable_lossless(cinfo, psv, pt);
+#endif
+
 #ifdef C_MULTISCAN_FILES_SUPPORTED
     if (scansarg != NULL)       /* process -scans if it was present */
       if (!read_scan_script(cinfo, scansarg))