input/vcd: add channel list checks for file re-read

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

diff --git a/src/input/vcd.c b/src/input/vcd.c
index 5b541430967c7cdcef5dd55e953df029abbe276c..e3c2347ac0875ff6f44f99f000077a691ce3a455 100644 (file)
--- a/src/input/vcd.c
+++ b/src/input/vcd.c
@@ -67,7 +67,7 @@
 
 #define LOG_PREFIX "input/vcd"
 
-#define CHUNK_SIZE (1024 * 1024)
+#define CHUNK_SIZE (4 * 1024 * 1024)
 
 struct context {
        gboolean started;
@@ -85,6 +85,7 @@ struct context {
        size_t samples_in_buffer;
        uint8_t *buffer;
        uint8_t *current_levels;
+       GSList *prev_sr_channels;
 };
 
 struct vcd_channel {
@@ -151,7 +152,11 @@ static gboolean parse_section(GString *buf, gchar **name, gchar **contents)
 
 static void free_channel(void *data)
 {
-       struct vcd_channel *vcd_ch = data;
+       struct vcd_channel *vcd_ch;
+
+       vcd_ch = data;
+       if (!vcd_ch)
+               return;
        g_free(vcd_ch->name);
        g_free(vcd_ch->identifier);
        g_free(vcd_ch);
@@ -171,6 +176,56 @@ static void remove_empty_parts(gchar **parts)
        *dest = NULL;
 }
 
+/*
+ * Keep track of a previously created channel list, in preparation of
+ * re-reading the input file. Gets called from reset()/cleanup() paths.
+ */
+static void keep_header_for_reread(const struct sr_input *in)
+{
+       struct context *inc;
+
+       inc = in->priv;
+       g_slist_free_full(inc->prev_sr_channels, sr_channel_free_cb);
+       inc->prev_sr_channels = in->sdi->channels;
+       in->sdi->channels = NULL;
+}
+
+/*
+ * Check whether the input file is being re-read, and refuse operation
+ * when essential parameters of the acquisition have changed in ways
+ * that are unexpected to calling applications. Gets called after the
+ * file header got parsed (again).
+ *
+ * Changing the channel list across re-imports of the same file is not
+ * supported, by design and for valid reasons, see bug #1215 for details.
+ * Users are expected to start new sessions when they change these
+ * essential parameters in the acquisition's setup. When we accept the
+ * re-read file, then make sure to keep using the previous channel list,
+ * applications may still reference them.
+ */
+static int check_header_in_reread(const struct sr_input *in)
+{
+       struct context *inc;
+
+       if (!in)
+               return FALSE;
+       inc = in->priv;
+       if (!inc)
+               return FALSE;
+       if (!inc->prev_sr_channels)
+               return TRUE;
+
+       if (sr_channel_lists_differ(inc->prev_sr_channels, in->sdi->channels)) {
+               sr_err("Channel list change not supported for file re-read.");
+               return FALSE;
+       }
+       g_slist_free_full(in->sdi->channels, sr_channel_free_cb);
+       in->sdi->channels = inc->prev_sr_channels;
+       inc->prev_sr_channels = NULL;
+
+       return TRUE;
+}
+
 /*
  * Parse VCD header to get values for context structure.
  * The context structure should be zeroed before calling this.
@@ -261,11 +316,13 @@ static gboolean parse_header(const struct sr_input *in, GString *buf)
        inc->current_levels = g_malloc0(inc->bytes_per_sample);
 
        inc->got_header = status;
+       if (status)
+               status = check_header_in_reread(in);
 
        return status;
 }
 
-static int format_match(GHashTable *metadata)
+static int format_match(GHashTable *metadata, unsigned int *confidence)
 {
        GString *buf, *tmpbuf;
        gboolean status;
@@ -283,7 +340,11 @@ static int format_match(GHashTable *metadata)
        g_free(name);
        g_free(contents);
 
-       return status ? SR_OK : SR_ERR;
+       if (!status)
+               return SR_ERR;
+       *confidence = 1;
+
+       return SR_OK;
 }
 
 /* Send all accumulated bytes from inc->buffer. */
@@ -404,6 +465,10 @@ static void parse_contents(const struct sr_input *in, char *data)
                                inc->prev_timestamp = inc->skip;
                        } else if (timestamp == inc->prev_timestamp) {
                                /* Ignore repeated timestamps (e.g. sigrok outputs these) */
+                       } else if (timestamp < inc->prev_timestamp) {
+                               sr_err("Invalid timestamp: %" PRIu64 " (smaller than previous timestamp).", timestamp);
+                               inc->skip_until_end = TRUE;
+                               break;
                        } else {
                                if (inc->compress != 0 && timestamp - inc->prev_timestamp > inc->compress) {
                                        /* Compress long idle periods */
@@ -606,7 +671,10 @@ static void cleanup(struct sr_input *in)
        struct context *inc;
 
        inc = in->priv;
+       keep_header_for_reread(in);
        g_slist_free_full(inc->channels, free_channel);
+       inc->channels = NULL;
+
        g_free(inc->buffer);
        inc->buffer = NULL;
        g_free(inc->current_levels);
@@ -618,9 +686,16 @@ static int reset(struct sr_input *in)
        struct context *inc = in->priv;
 
        cleanup(in);
-       inc->started = FALSE;
        g_string_truncate(in->buf, 0);
 
+       inc->started = FALSE;
+       inc->got_header = FALSE;
+       inc->prev_timestamp = 0;
+       inc->skip_until_end = FALSE;
+       inc->channelcount = 0;
+       /* The inc->channels list was released in cleanup() above. */
+       inc->buffer = g_malloc(CHUNK_SIZE);
+
        return SR_OK;
 }
 
@@ -648,7 +723,7 @@ static const struct sr_option *get_options(void)
 SR_PRIV struct sr_input_module input_vcd = {
        .id = "vcd",
        .name = "VCD",
-       .desc = "Value Change Dump",
+       .desc = "Value Change Dump data",
        .exts = (const char*[]){"vcd", NULL},
        .metadata = { SR_INPUT_META_HEADER | SR_INPUT_META_REQUIRED },
        .options = get_options,