Clean up exp_pdu_open() API.

It really shouldn't free the comment passed to it, as the caller
allocated it, and knows how to free it if necessary; it might not even
have been allocated.

Make the comment argument a "const char *" to 1) allow passing string
constants etc. and 2) to catch any attempts to free it in
exp_pdu_open().

Make the callers free it after exp_pdu_open() returns.

(Alternatively, we could have exp_pdu_open() take the file name argument
and generate the comment itself, so that all code paths generate the
same comment.)

Change-Id: I6e6924b05565761b641a6c3b4d9a2e97f4264e1b
Ping-Bug: 15365
Reviewed-on: https://code.wireshark.org/review/31105
Reviewed-by: Guy Harris <guy@alum.mit.edu>

4 files changed, 4 insertions, 5 deletions

diff --git a/tshark.c b/tshark.c
index 00c28db781..e02b61b663 100644
--- a/tshark.c
+++ b/tshark.c
@@ -1977,10 +1977,10 @@ real_main(int argc, char *argv[])
       /* Activate the export PDU tap */
       comment = g_strdup_printf("Dump of PDUs from %s", cf_name);
       err = exp_pdu_open(&exp_pdu_tap_data, exp_fd, comment);
+      g_free(comment);
       if (err != 0) {
           cfile_dump_open_failure_message("TShark", exp_pdu_filename, err,
                                           WTAP_FILE_TYPE_SUBTYPE_PCAPNG);
-          g_free(comment);
           exit_status = INVALID_EXPORT;
           goto clean_exit;
       }
diff --git a/ui/export_pdu_ui_utils.c b/ui/export_pdu_ui_utils.c
index a567a61991..c9e40b7a24 100644
--- a/ui/export_pdu_ui_utils.c
+++ b/ui/export_pdu_ui_utils.c
@@ -43,8 +43,8 @@ exp_pdu_file_open(exp_pdu_t *exp_pdu_tap_data)
 
     comment = g_strdup_printf("Dump of PDUs from %s", cfile.filename);
     err = exp_pdu_open(exp_pdu_tap_data, import_file_fd, comment);
+    g_free(comment);
     if (err != 0) {
-        g_free(comment);
         cfile_dump_open_failure_alert_box(capfile_name ? capfile_name : "temporary file",
                                           err, WTAP_FILE_TYPE_SUBTYPE_PCAPNG);
         goto end;
diff --git a/ui/tap_export_pdu.c b/ui/tap_export_pdu.c
index 25232f0452..d3302a5aca 100644
--- a/ui/tap_export_pdu.c
+++ b/ui/tap_export_pdu.c
@@ -82,7 +82,7 @@ export_pdu_packet(void *tapdata, packet_info *pinfo, epan_dissect_t *edt, const
 }
 
 int
-exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, char *comment)
+exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, const char *comment)
 {
 
     int   err;
@@ -103,7 +103,6 @@ exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, char *comment)
 
     /* options */
     wtap_block_add_string_option(shb_hdr, OPT_COMMENT, comment, strlen(comment));
-    g_free(comment);
 
     /*
      * UTF-8 string containing the name of the operating system used to create
diff --git a/ui/tap_export_pdu.h b/ui/tap_export_pdu.h
index ea5c4077e1..9ae2dea65f 100644
--- a/ui/tap_export_pdu.h
+++ b/ui/tap_export_pdu.h
@@ -41,7 +41,7 @@ char *exp_pdu_pre_open(const char *tap_name, const char *filter,
 *
 * @return 0 on success or a wtap error code.
 */
-int exp_pdu_open(exp_pdu_t *data, int fd, char *comment);
+int exp_pdu_open(exp_pdu_t *data, int fd, const char *comment);
 
 /* Stops the PDUs export. */
 int exp_pdu_close(exp_pdu_t *exp_pdu_tap_data);