input/trace32_ad: fix potential buffer overflow for unexpected input data

[libsigrok.git] / src / input / input.c

diff --git a/src/input/input.c b/src/input/input.c
index 48660d379b9b6e69fde4546cbe8f91a7a67669b9..2a23aec2bd81d4a7a4326fb8c06c9acf3b1c47f4 100644 (file)
--- a/src/input/input.c
+++ b/src/input/input.c
@@ -29,6 +29,8 @@
 #define LOG_PREFIX "input"
 /** @endcond */
 
+#define CHUNK_SIZE     (4 * 1024 * 1024)
+
 /**
  * @file
  *
@@ -338,8 +340,10 @@ static gboolean check_required_metadata(const uint8_t *metadata, uint8_t *avail)
  * Try to find an input module that can parse the given buffer.
  *
  * The buffer must contain enough of the beginning of the file for
- * the input modules to find a match. This is format-dependent, but
- * 128 bytes is normally enough.
+ * the input modules to find a match. This is format-dependent. When
+ * magic strings get checked, 128 bytes normally could be enough. Note
+ * that some formats try to parse larger header sections, and benefit
+ * from seeing a larger scope.
  *
  * If an input module is found, an instance is created into *in.
  * Otherwise, *in contains NULL. When multiple input moduless claim
@@ -462,11 +466,9 @@ SR_API int sr_input_scan_file(const char *filename, const struct sr_input **in)
                fclose(stream);
                return SR_ERR;
        }
-       /* This actually allocates 256 bytes to allow for NUL termination. */
-       header = g_string_sized_new(255);
+       header = g_string_sized_new(CHUNK_SIZE);
        count = fread(header->str, 1, header->allocated_len - 1, stream);
-
-       if (count != header->allocated_len - 1 && ferror(stream)) {
+       if (count < 1 || ferror(stream)) {
                sr_err("Failed to read %s: %s", filename, g_strerror(errno));
                fclose(stream);
                g_string_free(header, TRUE);
@@ -530,6 +532,22 @@ SR_API int sr_input_scan_file(const char *filename, const struct sr_input **in)
        return SR_ERR;
 }
 
+/**
+ * Return the input instance's module "class". This can be used to find out
+ * which input module handles a specific input file. This is especially
+ * useful when an application did not create the input stream by specifying
+ * an input module, but instead some shortcut or convenience wrapper did.
+ *
+ * @since 0.6.0
+ */
+SR_API const struct sr_input_module *sr_input_module_get(const struct sr_input *in)
+{
+       if (!in)
+               return NULL;
+
+       return in->module;
+}
+
 /**
  * Return the input instance's (virtual) device instance. This can be
  * used to find out the number of channels and other information.