util/spkmodem-recv: handle sample errors correctly

when calling fread(), errno may be set to EOVEFLOW if
the range being read will cause an integer overflow

if end-of-file is reached, errno may not be set. when
calling this function, you must check errno or check
feof() - ferror() should also be checked, so this check
is added immediately afterwards in the code

ferror() does not set errno, so ERR() is used to set
errno to ECANCELED as program exit status

further separate reading of frames into a new function

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/util/spkmodem_recv/spkmodem-recv.c b/util/spkmodem_recv/spkmodem-recv.c
index 1dcf5f18..93afd95a 100644
--- a/util/spkmodem_recv/spkmodem-recv.c
+++ b/util/spkmodem_recv/spkmodem-recv.c
@@ -21,6 +21,7 @@
 
 #define DEBUG 0
 #define FLUSH_TIMEOUT 1
+#define ERR() (errno = errno ? errno : ECANCELED)
 
 signed short frame[2 * SAMPLES_PER_FRAME];
 signed short pulse[2 * SAMPLES_PER_FRAME];
@@ -30,6 +31,7 @@ char ascii = 0;
 void handle_audio(void);
 void print_char(void);
 void fetch_sample(void);
+void read_frame(int ringpos);
 
 int
 main(int argc, char *argv[])
@@ -94,9 +96,7 @@ fetch_sample(void)
 	f1 -= pulse[ringpos];
 	f1 += pulse[(ringpos + SAMPLES_PER_FRAME) % (2 * SAMPLES_PER_FRAME)];
 	f2 -= pulse[(ringpos + SAMPLES_PER_FRAME) % (2 * SAMPLES_PER_FRAME)];
-	if (fread(frame + ringpos, 1, sizeof(frame[0]), stdin)
-			!= sizeof(frame[0]))
-		err(errno = ECANCELED, "Could not read frame.");
+	read_frame(ringpos);
 
 	pulse[ringpos] = (abs(frame[ringpos]) > THRESHOLD) ? 1 : 0;
 	if (pulse[ringpos++])
@@ -106,6 +106,16 @@ fetch_sample(void)
 }
 
 void
+read_frame(int ringpos)
+{
+	if (fread(frame + ringpos, 1, sizeof(frame[0]), stdin)
+			!= sizeof(frame[0]))
+		err(ERR(), "Could not read from frame.");
+	if (ferror(stdin) != 0)
+		err(ERR(), "Could not read from frame");
+}
+
+void
 print_char(void)
 {
 #if DEBUG