cmdutils: check file access functions return values

CC: libav-stable@libav.org
Bug-Id: CID 703706

cmdutils.c

@@ -1397,14 +1397,31 @@ int cmdutils_read_file(const char *filename, char **bufptr, size_t *size)
                strerror(errno));
         return AVERROR(errno);
     }
-    fseek(f, 0, SEEK_END);
-    *size = ftell(f);
-    fseek(f, 0, SEEK_SET);
+
+    ret = fseek(f, 0, SEEK_END);
+    if (ret == -1) {
+        ret = AVERROR(errno);
+        goto out;
+    }
+
+    ret = ftell(f);
+    if (ret < 0) {
+        ret = AVERROR(errno);
+        goto out;
+    }
+    *size = ret;
+
+    ret = fseek(f, 0, SEEK_SET);
+    if (ret == -1) {
+        ret = AVERROR(errno);
+        goto out;
+    }
+
     *bufptr = av_malloc(*size + 1);
     if (!*bufptr) {
         av_log(NULL, AV_LOG_ERROR, "Could not allocate file buffer\n");
-        fclose(f);
-        return AVERROR(ENOMEM);
+        ret = AVERROR(ENOMEM);
+        goto out;
     }
     ret = fread(*bufptr, 1, *size, f);
     if (ret < *size) {
@@ -1420,6 +1437,7 @@ int cmdutils_read_file(const char *filename, char **bufptr, size_t *size)
         (*bufptr)[(*size)++] = '\0';
     }
 
+out:
     fclose(f);
     return ret;
 }