Add some higher-level file-read APIs and use them.

Add wtap_read_bytes(), which takes a FILE_T, a pointer, a byte count, an
error number pointer, and an error string pointer as arguments, and that
treats a short read of any sort, including a read that returns 0 bytes,
as a WTAP_ERR_SHORT_READ error, and that returns the error number and
string through its last two arguments.

Add wtap_read_bytes_or_eof(), which is similar, but that treats a read
that returns 0 bytes as an EOF, supplying an error number of 0 as an EOF
indication.

Use those in file readers; that simplifies the code and makes it less
likely that somebody will fail to supply the error number and error
string on a file read error.

Change-Id: Ia5dba2a6f81151e87b614461349d611cffc16210
Reviewed-on: https://code.wireshark.org/review/4512
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 36 insertions, 18 deletions

diff --git a/wiretap/commview.c b/wiretap/commview.c
index e0c24326d1..b9154d965d 100644
--- a/wiretap/commview.c
+++ b/wiretap/commview.c
@@ -208,24 +208,42 @@ static gboolean
 commview_read_header(commview_header_t *cv_hdr, FILE_T fh, int *err,
     gchar **err_info)
 {
-	wtap_file_read_expected_bytes(&cv_hdr->data_len, 2, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->source_data_len, 2, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->version, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->year, 2, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->month, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->day, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->hours, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->minutes, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->seconds, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->usecs, 4, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->flags, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->signal_level_percent, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->rate, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->band, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->channel, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->direction, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->signal_level_dbm, 1, fh, err, err_info);
-	wtap_file_read_expected_bytes(&cv_hdr->noise_level, 1, fh, err, err_info);
+	if (!wtap_read_bytes_or_eof(fh, &cv_hdr->data_len, 2, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->source_data_len, 2, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->version, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->year, 2, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->month, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->day, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->hours, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->minutes, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->seconds, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->usecs, 4, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->flags, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->signal_level_percent, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->rate, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->band, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->channel, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->direction, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->signal_level_dbm, 1, err, err_info))
+		return FALSE;
+	if (!wtap_read_bytes(fh, &cv_hdr->noise_level, 1, err, err_info))
+		return FALSE;
 
 	/* Convert multi-byte values from little endian to host endian format */
 	cv_hdr->data_len = GUINT16_FROM_LE(cv_hdr->data_len);