Fix: unplug memory leak that causes popt-0.13 to segfault

popt-0.16 poptGetArg() causes a memory leak, but freeing that memory
goes against popt(3) documented use, and against the 0.13 behavior,
which triggers a segfault on free(). So leave this small,
one-time-per-execution, memory leak in place.

Fixes #380

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/converter/babeltrace.c b/converter/babeltrace.c
index 30b655d8dd938a67c878699b9be1bcd8b6fc10b1..b24d0102fba72a7428be2f642ab22082ec687caf 100644 (file)
--- a/converter/babeltrace.c
+++ b/converter/babeltrace.c
@@ -48,12 +48,15 @@
 
 #define DEFAULT_FILE_ARRAY_SIZE        1
 
-/*
- * casting these to const char * to please libpopt. It allocates memory
- * behind our back (this is of course not documented).
- */
 static char *opt_input_format, *opt_output_format;
 
+/*
+ * We are not freeing opt_input_paths ipath elements when exiting from
+ * main() for backward compatibility with libpop 0.13, which does not
+ * allocate copies for arguments returned by poptGetArg(), and for
+ * general compatibility with the documented behavior. This is known to
+ * cause a small memory leak with libpop 0.16.
+ */
 static GPtrArray *opt_input_paths;
 static char *opt_output_path;
 
@@ -91,7 +94,10 @@ enum {
 /*
  * We are _not_ using POPT_ARG_STRING ability to store directly into
  * variables, because we want to cast the return to non-const, which is
- * not possible without using poptGetOptArg explicitly.
+ * not possible without using poptGetOptArg explicitly. This helps us
+ * controlling memory allocation correctly without making assumptions
+ * about undocumented behaviors. poptGetOptArg is documented as
+ * requiring the returned const char * to be freed by the caller.
  */
 static struct poptOption long_options[] = {
        /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
@@ -249,7 +255,7 @@ static int parse_options(int argc, char **argv)
 {
        poptContext pc;
        int opt, ret = 0;
-       char *ipath;
+       const char *ipath;
 
        if (argc == 1) {
                usage(stdout);
@@ -360,7 +366,7 @@ static int parse_options(int argc, char **argv)
        }
 
        do {
-               ipath = (char *) poptGetArg(pc);
+               ipath = poptGetArg(pc);
                if (ipath)
                        g_ptr_array_add(opt_input_paths, (gpointer) ipath);
        } while (ipath);
@@ -672,10 +678,6 @@ end:
        free(opt_input_format);
        free(opt_output_format);
        free(opt_output_path);
-       for (i = 0; i < opt_input_paths->len; i++) {
-               char *ipath = g_ptr_array_index(opt_input_paths, i);
-               free(ipath);
-       }
        g_ptr_array_free(opt_input_paths, TRUE);
        if (partial_error)
                exit(EXIT_FAILURE);