Safely exits when it is impossible to seek back in the audio file

src/fm_mpx.c

@@ -176,7 +176,10 @@ int fm_mpx_get_samples(float *mpx_buffer) {
                         return -1;
                     }
                     if(audio_len == 0) {
-                        sf_seek(inf, 0, SEEK_SET);
+                        if( sf_seek(inf, 0, SEEK_SET) < 0 ) {
+                            fprintf(stderr, "Could not rewind in audio file, terminating\n");
+                            return -1;
+                        }
                     } else {
                         break;
                     }

src/pi_fm_rds.c

@@ -483,7 +483,9 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
         while (free_slots >= SUBSIZE) {
             // get more baseband samples if necessary
             if(data_len == 0) {
-                fm_mpx_get_samples(data);
+                if( fm_mpx_get_samples(data) < 0 ) {
+                    terminate(0);
+                }
                 data_len = DATA_SIZE;
                 data_index = 0;
             }

src/rds_wav.c

@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <math.h>
 #include <sndfile.h>
+#include <strings.h>
 
 #include "rds.h"
 #include "fm_mpx.h"
@@ -38,7 +39,7 @@
 int main(int argc, char **argv) {
     if(argc < 4) {
         fprintf(stderr, "Error: missing argument.\n");
-        fprintf(stderr, "Syntax: rds_wav <in_file> <out.wav> <text>\n");
+        fprintf(stderr, "Syntax: rds_wav <in_audio.wav> <out_mpx.wav> <text>\n");
         return EXIT_FAILURE;
     }
     
@@ -77,7 +78,7 @@ int main(int argc, char **argv) {
     float mpx_buffer[LENGTH];
 
     for(int j=0; j<40; j++) {
-        fm_mpx_get_samples(mpx_buffer);
+        if( fm_mpx_get_samples(mpx_buffer) < 0 ) break;
         
         // scale samples
         for(int i=0; i<LENGTH; i++) {