notmuch show: Initial implementation (headers only)

We're using a delimiter syntax that Keith is optimistic about
being able to easily parse in emacs. Note: We're not escaping
any occurrence of the delimiters in the message yet, so we'll
need to fix that.

message-file.c

@@ -39,6 +39,7 @@ struct _notmuch_message_file {
     GHashTable *headers;
     int broken_headers;
     int good_headers;
+    size_t header_size; /* Length of full message header in bytes. */
 
     /* Parsing state */
     char *line;
@@ -204,6 +205,9 @@ copy_header_unfolding (header_value_closure_t *value,
     }
 }
 
+/* As a special-case, a value of NULL for header_desired will force
+ * the entire header to be parsed if it is not parsed already. This is
+ * used by the _notmuch_message_file_get_headers_end function. */
 const char *
 notmuch_message_file_get_header (notmuch_message_file_t *message,
 				 const char *header_desired)
@@ -215,9 +219,13 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 
     message->parsing_started = 1;
 
-    contains = g_hash_table_lookup_extended (message->headers,
-					     header_desired, NULL,
-					     (gpointer *) &value);
+    if (header_desired == NULL)
+	contains = 0;
+    else
+	contains = g_hash_table_lookup_extended (message->headers,
+						 header_desired, NULL,
+						 (gpointer *) &value);
+
     if (contains && value)
 	return value;
 
@@ -225,7 +233,7 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 	return NULL;
 
 #define NEXT_HEADER_LINE(closure)				\
-    do {							\
+    while (1) {							\
 	ssize_t bytes_read = getline (&message->line,		\
 				      &message->line_size,	\
 				      message->file);		\
@@ -242,7 +250,11 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 	{							\
 	    copy_header_unfolding ((closure), message->line);	\
 	}							\
-    } while (*message->line == ' ' || *message->line == '\t');
+	if (*message->line == ' ' || *message->line == '\t')	\
+	    message->header_size += strlen (message->line);	\
+	else							\
+	    break;						\
+    }
 
     if (message->line == NULL)
 	NEXT_HEADER_LINE (NULL);
@@ -268,6 +280,8 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 	    continue;
 	}
 
+	message->header_size += strlen (message->line);
+
 	message->good_headers++;
 
 	header = xstrndup (message->line, colon - message->line);
@@ -290,7 +304,10 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 
 	NEXT_HEADER_LINE (&message->value);
 
-	match = (strcasecmp (header, header_desired) == 0);
+	if (header_desired == 0)
+	    match = 0;
+	else
+	    match = (strcasecmp (header, header_desired) == 0);
 
 	value = xstrdup (message->value.str);
 
@@ -314,7 +331,7 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
     /* We've parsed all headers and never found the one we're looking
      * for. It's probably just not there, but let's check that we
      * didn't make a mistake preventing us from seeing it. */
-    if (message->restrict_headers &&
+    if (message->restrict_headers && header_desired &&
 	! g_hash_table_lookup_extended (message->headers,
 					header_desired, NULL, NULL))
     {
@@ -325,3 +342,40 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 
     return NULL;
 }
+
+static size_t
+_notmuch_message_file_get_header_size (notmuch_message_file_t *message)
+{
+    if (! message->parsing_finished)
+	notmuch_message_file_get_header (message, NULL);
+
+    if (! message->parsing_finished)
+	INTERNAL_ERROR ("Parsing for NULL header did not force parsing to finish.\n");
+
+    return message->header_size;
+}
+
+const char *
+notmuch_message_file_get_all_headers (notmuch_message_file_t *message)
+{
+    char *headers = NULL;
+    size_t header_size = _notmuch_message_file_get_header_size (message);
+
+    if (header_size == 0)
+	return "";
+
+    headers = talloc_size (message, header_size + 1);
+    if (unlikely (headers == NULL))
+	return NULL;
+
+    rewind (message->file);
+    if (fread (headers, 1, header_size, message->file) != header_size) {
+	fprintf (stderr, "Error: Short read occurred trying to read message header.\n");
+	talloc_free (headers);
+	return NULL;
+    }
+
+    headers[header_size] = '\0';
+
+    return headers;
+}

message.cc

@@ -232,26 +232,39 @@ notmuch_message_get_message_id (notmuch_message_t *message)
     return message->message_id;
 }
 
-const char *
-_notmuch_message_get_subject (notmuch_message_t *message)
+static void
+_notmuch_message_ensure_message_file (notmuch_message_t *message)
 {
-    if (! message->message_file) {
-	notmuch_message_file_t *message_file;
-	const char *filename;
+    const char *filename;
 
-	filename = notmuch_message_get_filename (message);
-	if (unlikely (filename == NULL))
-	    return NULL;
+    if (message->message_file)
+	return;
 
-	message_file = _notmuch_message_file_open_ctx (message, filename);
-	if (unlikely (message_file == NULL))
-	    return NULL;
+    filename = notmuch_message_get_filename (message);
+    if (unlikely (filename == NULL))
+	return;
 
-	message->message_file = message_file;
-    }
+    message->message_file = _notmuch_message_file_open_ctx (message, filename);
+}
 
-    return notmuch_message_file_get_header (message->message_file,
-					    "subject");
+const char *
+notmuch_message_get_header (notmuch_message_t *message, const char *header)
+{
+    _notmuch_message_ensure_message_file (message);
+    if (message->message_file == NULL)
+	return NULL;
+
+    return notmuch_message_file_get_header (message->message_file, header);
+}
+
+const char *
+notmuch_message_get_all_headers (notmuch_message_t *message)
+{
+    _notmuch_message_ensure_message_file (message);
+    if (message->message_file == NULL)
+	return NULL;
+
+    return notmuch_message_file_get_all_headers (message->message_file);
 }
 
 const char *

notmuch-private.h

@@ -280,6 +280,17 @@ const char *
 notmuch_message_file_get_header (notmuch_message_file_t *message,
 				 const char *header);
 
+/* Get the entire set of headers from an email message as a string.
+ *
+ * The returned value is owned by the notmuch message and is valid
+ * only until the message is closed. The caller should copy it if
+ * needing to modify the value or to hold onto it for longer.
+ *
+ * Returns NULL in the case of any error.
+ */
+const char *
+notmuch_message_file_get_all_headers (notmuch_message_file_t *message);
+
 /* date.c */
 
 /* Parse an RFC 8222 date string to a time_t value.

notmuch.c

@@ -800,8 +800,69 @@ search_command (int argc, char *argv[])
 static int
 show_command (unused (int argc), unused (char *argv[]))
 {
-    fprintf (stderr, "Error: show is not implemented yet.\n");
-    return 1;
+    void *local = talloc_new (NULL);
+    char *query_string;
+    notmuch_database_t *notmuch = NULL;
+    notmuch_query_t *query = NULL;
+    notmuch_message_results_t *messages;
+    notmuch_message_t *message;
+    int ret = 0;
+
+    if (argc != 1) {
+	fprintf (stderr, "Error: \"notmuch show\" requires exactly one thread-ID argument.\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    notmuch = notmuch_database_open (NULL);
+    if (notmuch == NULL) {
+	ret = 1;
+	goto DONE;
+    }
+
+    query_string = talloc_asprintf (local, "thread:%s", argv[0]);
+    if (query_string == NULL) {
+	fprintf (stderr, "Out of memory\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    query = notmuch_query_create (notmuch, query_string);
+    if (query == NULL) {
+	fprintf (stderr, "Out of memory\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    for (messages = notmuch_query_search_messages (query);
+	 notmuch_message_results_has_more (messages);
+	 notmuch_message_results_advance (messages))
+    {
+	message = notmuch_message_results_get (messages);
+
+	printf ("%%message{\n");
+
+	printf ("%%header{\n");
+
+	printf ("%s", notmuch_message_get_all_headers (message));
+
+	printf ("%%header}\n");
+	printf ("%%message}\n");
+
+	notmuch_message_destroy (message);
+    }
+
+  DONE:
+    if (local)
+	talloc_free (local);
+
+    if (query)
+	notmuch_query_destroy (query);
+
+    if (notmuch)
+	notmuch_database_close (notmuch);
+
+    return ret;
 }
 
 static int

notmuch.h

@@ -617,6 +617,35 @@ notmuch_message_get_thread_id (notmuch_message_t *message);
 const char *
 notmuch_message_get_filename (notmuch_message_t *message);
 
+/* Get the value of the specified header from 'message'.
+ *
+ * The value will be read from the actual message file, not from the
+ * notmuch database. The header name is case insensitive.
+ *
+ * The returned string belongs to the message so should not be
+ * modified or freed by the caller (nor should it be referenced after
+ * the message is destroyed).
+ *
+ * Returns NULL if the message does not contain a header line matching
+ * 'header' of if any error occurs.
+ */
+const char *
+notmuch_message_get_header (notmuch_message_t *message, const char *header);
+
+/* Get the entire set of headers from an email message as a string.
+ *
+ * The value will be read from the actual message file, not from the
+ * notmuch database.
+ *
+ * The returned value is owned by the notmuch message and is valid
+ * only until the message is closed. The caller should copy it if
+ * needing to modify the value or to hold onto it for longer.
+ *
+ * Returns NULL in the case of any error.
+ */
+const char *
+notmuch_message_get_all_headers (notmuch_message_t *message);
+
 /* Get the tags for 'message', returning a notmuch_tags_t object which
  * can be used to iterate over all tags.
  *

query.cc

@@ -212,7 +212,7 @@ notmuch_query_search_threads (notmuch_query_t *query)
 	    thread = _notmuch_thread_create (query, query->notmuch,
 					     thread_id);
 
-	    subject = _notmuch_message_get_subject (message);
+	    subject = notmuch_message_get_header (message, "subject");
 
 	    _notmuch_thread_set_subject (thread, subject);