input: unbreak automatic format detection when reading from stdin

[sigrok-cli.git] / input.c

diff --git a/input.c b/input.c
index 6c149722588db3a88ff0f7ca3618a4f213f77426..eb496ee7a54d4c2a806c248f282bbf05efb94178 100644 (file)
--- a/input.c
+++ b/input.c
@@ -44,6 +44,7 @@ static void load_input_file_module(struct df_arg_desc *df_arg)
        ssize_t len;
        char *mod_id;
        gboolean is_stdin;
+       gboolean push_scan_data;
 
        if (!sr_input_list())
                g_critical("No supported input formats available.");
@@ -56,6 +57,7 @@ static void load_input_file_module(struct df_arg_desc *df_arg)
        }
 
        is_stdin = strcmp(opt_input_file, "-") == 0;
+       push_scan_data = FALSE;
        fd = 0;
        buf = g_string_sized_new(CHUNK_SIZE);
        if (mod_id) {
@@ -108,6 +110,7 @@ static void load_input_file_module(struct df_arg_desc *df_arg)
                                                g_strerror(errno));
                        buf->len = len;
                        sr_input_scan_buffer(buf, &in);
+                       push_scan_data = TRUE;
                }
                if (!in)
                        g_critical("Error: no input module found for this file.");
@@ -116,15 +119,33 @@ static void load_input_file_module(struct df_arg_desc *df_arg)
        df_arg->session = session;
        sr_session_datafeed_callback_add(session, datafeed_in, df_arg);
 
+       /*
+        * Implementation detail: The combination of reading from stdin
+        * and automatic file format detection may have pushed the first
+        * chunk of input data into the input module's data accumulator,
+        * _bypassing_ the .receive() callback. It is essential to call
+        * .receive() before calling .end() for files of size smaller than
+        * CHUNK_SIZE (which is a typical case). So that sdi becomes ready.
+        * Fortunately all input modules accept .receive() calls with
+        * a zero length, and inspect whatever was accumulated so far.
+        *
+        * After that optional initial push of data which was queued
+        * above during format detection, continue reading remaining
+        * chunks from the input file until EOF is seen.
+        */
        got_sdi = FALSE;
        while (TRUE) {
                g_string_truncate(buf, 0);
-               len = read(fd, buf->str, CHUNK_SIZE);
+               if (push_scan_data)
+                       len = 0;
+               else
+                       len = read(fd, buf->str, CHUNK_SIZE);
                if (len < 0)
                        g_critical("Read failed: %s", g_strerror(errno));
-               if (len == 0)
+               if (len == 0 && !push_scan_data)
                        /* End of file or stream. */
                        break;
+               push_scan_data = FALSE;
                buf->len = len;
                if (sr_input_send(in, buf) != SR_OK)
                        break;
@@ -148,7 +169,6 @@ static void load_input_file_module(struct df_arg_desc *df_arg)
 
        df_arg->session = NULL;
        sr_session_destroy(session);
-
 }
 
 void load_input_file(gboolean do_props)