Fix unchecked strdup() return values in lib_ccx (#2213)

Two related strdup bugs across multiple lib_ccx files:

1. strdup(variable) return not checked for NULL — use after potential
   NULL dereference causes undefined behavior / segfault on OOM.
   Fixed by adding NULL check + fatal(EXIT_NOT_ENOUGH_MEMORY, ...).

2. strdup("literal") in get_buffer_type_str returned directly as
   function result — unchecked and leaks memory on every call since
   the function has no callers that free it.  Fixed by removing strdup
   and returning string literals directly; return type changed from
   char * to const char * (no callers exist, no header declaration).

Files changed:
  src/lib_ccx/ccx_common_common.c
  src/lib_ccx/ccx_encoders_common.c
  src/lib_ccx/ccx_encoders_helpers.c
  src/lib_ccx/configuration.c
  src/lib_ccx/hardsubx.c
  src/lib_ccx/hardsubx_decoder.c
  src/lib_ccx/ocr.c
  src/lib_ccx/output.c
  src/lib_ccx/ts_functions.c

Fixes #2194

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib_ccx/ccx_common_common.c

@@ -59,6 +59,9 @@ int add_cc_sub_text(struct cc_subtitle *sub, char *str, LLONG start_time,
 	sub->type = CC_TEXT;
 	sub->enc_type = e_type;
 	sub->data = strdup(str);
+	if (sub->data == NULL)
+		ccx_common_logging.fatal_ftn(EXIT_NOT_ENOUGH_MEMORY,
+					     "In add_cc_sub_text: Not enough memory for subtitle data.\n");
 	sub->datatype = CC_DATATYPE_GENERIC;
 	sub->nb_data = str ? strlen(str) : 0;
 	sub->start_time = start_time;

src/lib_ccx/ccx_encoders_common.c

@@ -607,7 +607,11 @@ static int init_output_ctx(struct encoder_ctx *ctx, struct encoder_cfg *cfg)
 				char *basefilename = get_basename(cfg->output_filename);
 				extension = get_file_extension(cfg->write_format);
 
-				ret = init_write(&ctx->out[0], strdup(cfg->output_filename), cfg->with_semaphore);
+				char *fname0 = strdup(cfg->output_filename);
+				if (fname0 == NULL)
+					fatal(EXIT_NOT_ENOUGH_MEMORY,
+					      "In init_output_ctx: Not enough memory for output filename.\n");
+				ret = init_write(&ctx->out[0], fname0, cfg->with_semaphore);
 				check_ret(cfg->output_filename);
 				ret = init_write(&ctx->out[1], create_outfilename(basefilename, "_2", extension), cfg->with_semaphore);
 				check_ret(ctx->out[1].filename);
@@ -615,7 +619,11 @@ static int init_output_ctx(struct encoder_ctx *ctx, struct encoder_cfg *cfg)
 			}
 			else
 			{
-				ret = init_write(ctx->out, strdup(cfg->output_filename), cfg->with_semaphore);
+				char *fname = strdup(cfg->output_filename);
+				if (fname == NULL)
+					fatal(EXIT_NOT_ENOUGH_MEMORY,
+					      "In init_output_ctx: Not enough memory for output filename.\n");
+				ret = init_write(ctx->out, fname, cfg->with_semaphore);
 				check_ret(cfg->output_filename);
 			}
 		}

src/lib_ccx/ccx_encoders_helpers.c

@@ -98,6 +98,9 @@ void call_function_if_match(unsigned char *line, struct word_list *list, void (*
 	    '{', '|', '}', '~', '\0'};
 
 	unsigned char *line_token = strdup(line);
+	if (line_token == NULL)
+		ccx_common_logging.fatal_ftn(EXIT_NOT_ENOUGH_MEMORY,
+					     "In call_function_if_match: Not enough memory for line copy.\n");
 	unsigned char *c = strtok(line_token, delim);
 
 	if (c != NULL)
@@ -127,6 +130,9 @@ void telx_correct_case(char *sub_line)
 	    '{', '|', '}', '~', '\0'};
 
 	char *line = strdup(((char *)sub_line));
+	if (line == NULL)
+		ccx_common_logging.fatal_ftn(EXIT_NOT_ENOUGH_MEMORY,
+					     "In telx_correct_case: Not enough memory for line copy.\n");
 	char *oline = (char *)sub_line;
 	char *c = strtok(line, delim);
 	if (c == NULL)

src/lib_ccx/configuration.c

@@ -19,6 +19,9 @@ static int set_string(void *var, char *val)
 		return -1;
 
 	val1 = strdup(val);
+	if (val1 == NULL)
+		fatal(EXIT_NOT_ENOUGH_MEMORY,
+		      "In set_string: Not enough memory for string copy.\n");
 	*p = val1;
 	return 0;
 }

src/lib_ccx/hardsubx.c

@@ -233,7 +233,16 @@ struct lib_hardsubx_ctx *_init_hardsubx(struct ccx_s_options *options)
 
 	ctx->tess_handle = TessBaseAPICreate();
 	char *pars_vec = strdup("debug_file");
+	if (pars_vec == NULL)
+		fatal(EXIT_NOT_ENOUGH_MEMORY,
+		      "In _init_hardsubx: Not enough memory for pars_vec.\n");
 	char *pars_values = strdup("/dev/null");
+	if (pars_values == NULL)
+	{
+		free(pars_vec);
+		fatal(EXIT_NOT_ENOUGH_MEMORY,
+		      "In _init_hardsubx: Not enough memory for pars_values.\n");
+	}
 	char *tessdata_path = NULL;
 
 	char *lang = (char *)options->ocrlang;

src/lib_ccx/hardsubx_decoder.c

@@ -227,6 +227,9 @@ void hardsubx_process_frames_linear(struct lib_hardsubx_ctx *ctx, struct encoder
 						if (subtitle_text)
 						{
 							prev_subtitle_text = strdup(subtitle_text);
+							if (prev_subtitle_text == NULL)
+								fatal(EXIT_NOT_ENOUGH_MEMORY,
+								      "In hardsubx_process_frames_linear: Not enough memory for subtitle text.\n");
 							prev_sub_encoded = 0;
 						}
 					}
@@ -251,6 +254,9 @@ void hardsubx_process_frames_linear(struct lib_hardsubx_ctx *ctx, struct encoder
 					prev_begin_time = prev_end_time + 1;
 					prev_end_time = convert_pts_to_ms(ctx->packet.pts, ctx->format_ctx->streams[ctx->video_stream_id]->time_base);
 					prev_subtitle_text = strdup(subtitle_text);
+					if (prev_subtitle_text == NULL)
+						fatal(EXIT_NOT_ENOUGH_MEMORY,
+						      "In hardsubx_process_frames_linear: Not enough memory for subtitle text.\n");
 					prev_sub_encoded = 0;
 				}
 				prev_packet_pts = ctx->packet.pts;
@@ -514,6 +520,9 @@ void process_hardsubx_linear_frames_and_normal_subs(struct lib_hardsubx_ctx *har
 								if (subtitle_text_hard)
 								{
 									prev_subtitle_text_hard = strdup(subtitle_text_hard);
+									if (prev_subtitle_text_hard == NULL)
+										fatal(EXIT_NOT_ENOUGH_MEMORY,
+										      "In process_hardsubx_linear_frames_and_normal_subs: Not enough memory for subtitle text.\n");
 									prev_sub_encoded_hard = 0;
 								}
 							}
@@ -525,6 +534,9 @@ void process_hardsubx_linear_frames_and_normal_subs(struct lib_hardsubx_ctx *har
 							prev_begin_time_hard = prev_end_time_hard + 1;
 							prev_end_time_hard = convert_pts_to_ms(hard_ctx->packet.pts, hard_ctx->format_ctx->streams[hard_ctx->video_stream_id]->time_base);
 							prev_subtitle_text_hard = strdup(subtitle_text_hard);
+							if (prev_subtitle_text_hard == NULL)
+								fatal(EXIT_NOT_ENOUGH_MEMORY,
+								      "In process_hardsubx_linear_frames_and_normal_subs: Not enough memory for subtitle text.\n");
 							prev_sub_encoded_hard = 0;
 						}
 						prev_packet_pts_hard = hard_ctx->packet.pts;

src/lib_ccx/ocr.c

@@ -519,6 +519,9 @@ static char *ocr_single_line(struct ocrCtx *ctx, PIX *line_pix)
 		{
 			text = strdup(tess_text);
 			TessDeleteText(tess_text);
+			if (text == NULL)
+				fatal(EXIT_NOT_ENOUGH_MEMORY,
+				      "In ocr_single_line: Not enough memory for OCR text.\n");
 		}
 	}
 

src/lib_ccx/output.c

@@ -70,6 +70,9 @@ int init_write(struct ccx_s_write *wb, char *filename, int with_semaphore)
 	wb->temporarily_closed = 0;
 	wb->filename = filename;
 	wb->original_filename = strdup(filename);
+	if (wb->original_filename == NULL)
+		fatal(EXIT_NOT_ENOUGH_MEMORY,
+		      "In init_write: Not enough memory for original filename.\n");
 
 	wb->with_semaphore = with_semaphore;
 	wb->append_mode = ccx_options.enc_cfg.append_mode;

src/lib_ccx/ts_functions.c

@@ -27,39 +27,39 @@ uint64_t last_pts = 0;		// PTS of last PES packet (debug purposes)
 // Descriptions for ts ccx_stream_type
 const char *desc[256];
 
-char *get_buffer_type_str(struct cap_info *cinfo)
+const char *get_buffer_type_str(struct cap_info *cinfo)
 {
 	if (cinfo->stream == CCX_STREAM_TYPE_VIDEO_MPEG2)
 	{
-		return strdup("MPG");
+		return "MPG";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_VIDEO_H264)
 	{
-		return strdup("H.264");
+		return "H.264";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_VIDEO_HEVC)
 	{
-		return strdup("HEVC");
+		return "HEVC";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_PRIVATE_MPEG2 && cinfo->codec == CCX_CODEC_ISDB_CC)
 	{
-		return strdup("ISDB CC subtitle");
+		return "ISDB CC subtitle";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_PRIVATE_MPEG2 && cinfo->codec == CCX_CODEC_DVB)
 	{
-		return strdup("DVB subtitle");
+		return "DVB subtitle";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_UNKNOWNSTREAM && ccx_options.hauppauge_mode)
 	{
-		return strdup("Hauppage");
+		return "Hauppage";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_PRIVATE_MPEG2 && cinfo->codec == CCX_CODEC_TELETEXT)
 	{
-		return strdup("Teletext");
+		return "Teletext";
 	}
 	else if (cinfo->stream == CCX_STREAM_TYPE_PRIVATE_MPEG2 && cinfo->codec == CCX_CODEC_ATSC_CC)
 	{
-		return strdup("CC in private MPEG packet");
+		return "CC in private MPEG packet";
 	}
 	else
 	{