Add C API qpdf_free_buffer to release memory allocated by stream data functions

Chao Li(VISION)
1 parent ff2a78f5
Showing 4 changed files with 22 additions and 3 deletions
include/qpdf/qpdf-c.h
libqpdf/qpdf-c.cc
qpdf/qpdf-ctest.c
qpdf/qpdf.testcov
@@ -927,6 +927,14 @@ extern &quot;C&quot; {
     QPDF_ERROR_CODE qpdf_oh_get_page_content_data(
         qpdf_data qpdf, qpdf_oh page_oh, unsigned char** bufp, size_t* len);
  
+    /* Call free to release the buffer allocated with malloc. This function can be used to free 
+     * buffers that were dynamically allocated by qpdf functions such as qpdf_oh_get_stream_data
+     * or qpdf_oh_get_page_content_data. The caller is responsible for calling qpdf_free_buffer
+     * to manage memory properly and avoid memory leaks.
+     */
+    QPDF_DLL
+    void qpdf_free_buffer(unsigned char** bufp);
+
     /* The data pointed to by bufp will be copied by the library. It does not need to remain valid
      * after the call returns.
      */
@@ -1772,6 +1772,16 @@ qpdf_oh_get_page_content_data(qpdf_data qpdf, qpdf_oh page_oh, unsigned char** b
 }
  
 void
+qpdf_free_buffer(unsigned char** bufp)
+{
+    QTC::TC("qpdf", "qpdf-c called qpdf_free_buffer");
+    if (bufp && *bufp) {
+        free(*bufp);
+        *bufp = nullptr;
+    }
+}
+
+void
 qpdf_oh_replace_stream_data(
     qpdf_data qpdf,
     qpdf_oh stream_oh,
@@ -1151,7 +1151,7 @@ test38(char const* infile, char const* password, char const* outfile, char const
     assert(qpdf_oh_get_stream_data(qpdf, stream, qpdf_dl_none, 0, &buf, &len) == 0);
     assert(len == 53);
     assert(((int)buf[0] == 'x') && ((int)buf[1] == 0234));
-    free(buf);
+    qpdf_free_buffer(&buf);
  
     /* Test whether filterable */
     QPDF_BOOL filtered = QPDF_FALSE;
@@ -1169,8 +1169,8 @@ test38(char const* infile, char const* password, char const* outfile, char const
     assert(qpdf_oh_get_page_content_data(qpdf, page2, &buf2, &len) == 0);
     assert(len == 47);
     assert(memcmp(buf, buf2, len) == 0);
-    free(buf);
-    free(buf2);
+    qpdf_free_buffer(&buf);
+    qpdf_free_buffer(&buf2);
  
     /* errors */
     printf("page content on broken page\n");
@@ -626,6 +626,7 @@ qpdf-c stream data filtered set 1
 qpdf-c stream data buf set 1
 qpdf-c called qpdf_oh_get_page_content_data 0
 qpdf-c called qpdf_oh_replace_stream_data 0
+qpdf-c called qpdf_free_buffer 0
 qpdf-c silence oh errors 0
 qpdf-c called qpdf_oh_get_binary_string_value 0
 qpdf-c called qpdf_oh_get_binary_utf8_value 0