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, 37 insertions, 27 deletions

diff --git a/wiretap/wtap-int.h b/wiretap/wtap-int.h
index fa95119dfe..c550502b81 100644
--- a/wiretap/wtap-int.h
+++ b/wiretap/wtap-int.h
@@ -245,33 +245,6 @@ extern gint wtap_num_file_types;
     }
 #endif
 
-#define wtap_file_read_unknown_bytes(target, num_bytes, fh, err, err_info) \
-    G_STMT_START \
-    { \
-        int _bytes_read; \
-        _bytes_read = file_read((target), (num_bytes), (fh)); \
-        if (_bytes_read != (int) (num_bytes)) { \
-            *(err) = file_error((fh), (err_info)); \
-            return FALSE; \
-        } \
-    } \
-    G_STMT_END
-
-#define wtap_file_read_expected_bytes(target, num_bytes, fh, err, err_info) \
-    G_STMT_START \
-    { \
-        int _bytes_read; \
-        _bytes_read = file_read((target), (num_bytes), (fh)); \
-        if (_bytes_read != (int) (num_bytes)) { \
-            *(err) = file_error((fh), (err_info)); \
-            if (*(err) == 0 && _bytes_read > 0) { \
-                *(err) = WTAP_ERR_SHORT_READ; \
-            } \
-            return FALSE; \
-        } \
-    } \
-    G_STMT_END
-
 /* glib doesn't have g_ptr_array_len of all things!*/
 #ifndef g_ptr_array_len
 #define g_ptr_array_len(a)      ((a)->len)
@@ -281,6 +254,43 @@ extern gint wtap_num_file_types;
 GSList *wtap_get_compressed_file_extensions(void);
 
 /*
+ * Read a given number of bytes from a file.
+ *
+ * If we succeed, return TRUE.
+ *
+ * If we get an EOF, return FALSE with *err set to 0, reporting this
+ * as an EOF.
+ *
+ * If we get fewer bytes than the specified number, return FALSE with
+ * *err set to WTAP_ERR_SHORT_READ, reporting this as a short read
+ * error.
+ *
+ * If we get a read error, return FALSE with *err and *err_info set
+ * appropriately.
+ */
+WS_DLL_PUBLIC
+gboolean
+wtap_read_bytes_or_eof(FILE_T fh, void *buf, unsigned int count, int *err,
+    gchar **err_info);
+
+/*
+ * Read a given number of bytes from a file.
+ *
+ * If we succeed, return TRUE.
+ *
+ * If we get fewer bytes than the specified number, including getting
+ * an EOF, return FALSE with *err set to WTAP_ERR_SHORT_READ, reporting
+ * this as a short read error.
+ *
+ * If we get a read error, return FALSE with *err and *err_info set
+ * appropriately.
+ */
+WS_DLL_PUBLIC
+gboolean
+wtap_read_bytes(FILE_T fh, void *buf, unsigned int count, int *err,
+    gchar **err_info);
+
+/*
  * Read packet data into a Buffer, growing the buffer as necessary.
  *
  * This returns an error on a short read, even if the short read hit