Refactor header parsing

1 files changed, 82 insertions, 52 deletions

diff --git a/wavextract.c b/wavextract.c
index 4192f64..137d1a0 100644
--- a/wavextract.c
+++ b/wavextract.c
@@ -61,6 +61,80 @@ static int usage(char* fn){
 	return EXIT_FAILURE;
 }
 
+int wave_verify_riff(int fd, hdr_riff_t* hdr){
+	if(read(fd, hdr, sizeof(hdr_riff_t)) != sizeof(hdr_riff_t)){
+		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
+		return 1;
+	}
+
+	if(memcmp(hdr->magic_riff, "RIFF", 4) || memcmp(hdr->magic_wave, "WAVE", 4)){
+		fprintf(stderr, "Invalid RIFF/WAVE magic - probably not a WAVE file\n");
+		return 1;
+	}
+
+	fprintf(stderr, "RIFF chunk size: %d\n", hdr->size);
+	return 0;
+}
+
+int wave_verify_fmt(int fd, hdr_fmt_t* hdr){
+	uint16_t extra_data;
+	uint8_t skip_byte;
+	size_t n;
+
+	if(read(fd, hdr, sizeof(hdr_fmt_t)) != sizeof(hdr_fmt_t)){
+		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
+		return 1;
+	}
+
+	if(memcmp(hdr->magic, "fmt ", 4)){
+		fprintf(stderr, "Invalid format header magic - format probably incompatible\n");
+		return 1;
+	}
+
+	fprintf(stderr, "Format chunk size: %d\n", hdr->size);
+	fprintf(stderr, "Format: %d\n", hdr->fmt);
+	fprintf(stderr, "Channels: %d\n", hdr->channels);
+	fprintf(stderr, "Samplerate: %d\n", hdr->sample_rate);
+	fprintf(stderr, "Byterate: %d\n", hdr->byte_rate);
+	fprintf(stderr, "Align: %d\n", hdr->bitdepth);
+	fprintf(stderr, "Samplebits: %d\n", hdr->samplebits);
+
+	if(hdr->fmt != 1){
+		if(read(fd, &extra_data, 2) != 2){
+			fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
+			return 1;
+		}
+	}
+	else if(hdr->size > 16 /* length of fmt header as counted from after the size member */){
+		fprintf(stderr, "Skipping %d additional header bytes:", hdr->size - 16);
+		for(n = 16; n < hdr->size; n++){
+			if(read(fd, &skip_byte, 1) != 1){
+				fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
+				return 1;
+			}
+			fprintf(stderr, " %02X", skip_byte);
+		}
+		fprintf(stderr, "\n");
+	}
+
+	return 0;
+}
+
+int wave_verify_data(int fd, hdr_data_t* hdr){
+	if(read(fd, hdr, sizeof(hdr_data_t)) != sizeof(hdr_data_t)){
+		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
+		return 1;
+	}
+
+	if(memcmp(hdr->magic, "data", 4)){
+		fprintf(stderr, "Invalid data magic\n");
+		return 1;
+	}
+
+	fprintf(stderr, "%d bytes of sample data in file\n", hdr->size);
+	return 0;
+}
+
 int main(int argc, char** argv){
 	size_t n;
 	#ifdef _WIN32
@@ -79,53 +153,24 @@ int main(int argc, char** argv){
 	}
 
 	hdr_riff_t riff;
-	if(read(source_fd, &riff, sizeof(riff)) != sizeof(riff)){
-		close(source_fd);
-		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
-		return EXIT_FAILURE;	
-	}
+	hdr_fmt_t fmt;
+	hdr_data_t data;
 
-	if(memcmp(riff.magic_riff, "RIFF", 4) || memcmp(riff.magic_wave, "WAVE", 4)){
+	if(wave_verify_riff(source_fd, &riff)){
 		close(source_fd);
-		fprintf(stderr, "Invalid RIFF/WAVE magic\n");
 		return EXIT_FAILURE;
 	}
 
-	fprintf(stderr, "Chunk size: %d\n", riff.size);
-
-	hdr_fmt_t fmt;
-	uint16_t extra_data;
-	if(read(source_fd, &fmt, sizeof(fmt)) != sizeof(fmt)){
+	if(wave_verify_fmt(source_fd, &fmt)){
 		close(source_fd);
-		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
-		return EXIT_FAILURE;	
+		return EXIT_FAILURE;
 	}
 
-	if(memcmp(fmt.magic, "fmt ", 4)){
+	if(wave_verify_data(source_fd, &data)){
 		close(source_fd);
-		fprintf(stderr, "Invalid format magic\n");
 		return EXIT_FAILURE;
 	}
 
-	fprintf(stderr, "Format chunk size: %d\n", fmt.size);
-	fprintf(stderr, "Format: %d\n", fmt.fmt);
-	fprintf(stderr, "Channels: %d\n", fmt.channels);
-	fprintf(stderr, "Samplerate: %d\n", fmt.sample_rate);
-	fprintf(stderr, "Byterate: %d\n", fmt.byte_rate);
-	fprintf(stderr, "Align: %d\n", fmt.bitdepth);
-	fprintf(stderr, "Samplebits: %d\n", fmt.samplebits);
-
-	if(fmt.fmt != 1){
-		read(source_fd, &extra_data, 2);
-	}
-
-	if(fmt.fmt == 1 && fmt.size > 16){
-		fprintf(stderr, "Skipping %d additional header bytes\n", fmt.size - 16);
-		for(n = 16; n < fmt.size; n++){
-			read(source_fd, &extra_data, 1);
-		}
-	}
-
 	/* For now, just skip further analysis and bail on incompatible format */
 	if(fmt.samplebits != 16){
 		close(source_fd);
@@ -133,25 +178,10 @@ int main(int argc, char** argv){
 		return EXIT_FAILURE;	
 	}
 
-	hdr_data_t data_header;
-	if(read(source_fd, &data_header, sizeof(data_header)) != sizeof(data_header)){
-		close(source_fd);
-		fprintf(stderr, "Failed to read input data: %s\n", strerror(errno));
-		return EXIT_FAILURE;	
-	}
-
-	if(memcmp(data_header.magic, "data", 4)){
-		close(source_fd);
-		fprintf(stderr, "Invalid data magic\n");
-		return EXIT_FAILURE;
-	}
-
-	fprintf(stderr, "%d bytes of sample data in file\n", data_header.size);
-
 	uint16_t sample;
 	uint8_t channel = 0;
 
-	for(n = 0; n < data_header.size / 2; n++){
+	for(n = 0; n < data.size / 2; n++){
 		//read sample
 		if(read(source_fd, &sample, 2) != 2){
 			close(source_fd);
@@ -175,6 +205,6 @@ int main(int argc, char** argv){
 	}
 
 	close(source_fd);
-	fprintf(stderr, "All done\n");
+	fprintf(stderr, "Done, exported %ld frames of data %d channels, processed %ld samples\n", n, fmt.channels, fmt.channels * n);
 	return EXIT_SUCCESS;
 }