drivers: Remove dependency on linker implementation specific behaviour

Makefile.am

@@ -168,15 +168,22 @@ libsigrok_la_SOURCES += \
 	src/scale/kern.c
 
 # Hardware drivers
-noinst_LTLIBRARIES = src/libdrivers.la
+noinst_LTLIBRARIES = src/libdrivers.la \
+	src/libdrivers_head.la src/libdrivers_tail.la
 
-src/libdrivers.o: src/libdrivers.la
-	$(AM_V_CCLD)$(LINK) src/libdrivers.la
+src/libdrivers.o: src/libdrivers.la \
+		src/libdrivers_head.la src/libdrivers_tail.la
+	$(AM_V_CCLD)$(LINK) src/libdrivers_head.la src/libdrivers.la \
+		src/libdrivers_tail.la
 src/libdrivers.lo: src/libdrivers.o
 	$(AM_V_GEN)echo "# Generated by libtool" > $@
 	$(AM_V_at)echo "pic_object='libdrivers.o'" >> $@
 	$(AM_V_at)echo "non_pic_object='libdrivers.o'" >> $@
 
+src_libdrivers_head_la_SOURCES = src/driver_list_start.c
+
+src_libdrivers_tail_la_SOURCES = src/driver_list_stop.c
+
 src_libdrivers_la_SOURCES = src/drivers.c
 
 if HW_AGILENT_DMM

src/driver_list_start.c

@@ -0,0 +1,33 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2017 Marcus Comstedt <marcus@mc.pp.se>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <glib.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+
+/*
+ * This marks the start of the driver list. This file must be linked
+ * before any actual drivers.
+ */
+
+SR_PRIV const struct sr_dev_driver *sr_driver_list__start[]
+	__attribute__((section (SR_DRIVER_LIST_SECTION),
+		       used, aligned(sizeof(struct sr_dev_driver *))))
+  = { NULL /* Dummy item, as zero length arrays are not allowed by C99 */ };

src/driver_list_stop.c

@@ -0,0 +1,33 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2017 Marcus Comstedt <marcus@mc.pp.se>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <glib.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+
+/*
+ * This marks the end of the driver list. This file must be linked
+ * after any actual drivers.
+ */
+
+SR_PRIV const struct sr_dev_driver *sr_driver_list__stop[]
+	__attribute__((section (SR_DRIVER_LIST_SECTION),
+		       used, aligned(sizeof(struct sr_dev_driver *))))
+  = { NULL /* Dummy item, as zero length arrays are not allowed by C99 */ };

src/drivers.c

@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2016 Lars-Peter Clausen <lars@metafoo.de>
  * Copyright (C) 2016 Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2017 Marcus Comstedt <marcus@mc.pp.se>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,17 +27,12 @@
 /*
  * sr_driver_list is a special section contains pointers to all the hardware
  * drivers built into the library. The __start and __stop symbols are
- * auto-generated by the linker (OSX needs a little help) and point to the start
- * and end of the section. They are used to iterate over the list of all
- * drivers.
+ * created from driver_list_start.c and driver_list_stop.c, and point to the
+ * start and end of the section. They are used to iterate over the list of
+ * all drivers.
  */
-#ifdef __APPLE__
-extern struct sr_dev_driver *__start_sr_driver_list __asm("section$start$__DATA$__sr_driver_list");
-extern struct sr_dev_driver *__stop_sr_driver_list __asm("section$end$__DATA$__sr_driver_list");
-#else
-extern struct sr_dev_driver *__start_sr_driver_list;
-extern struct sr_dev_driver *__stop_sr_driver_list;
-#endif
+SR_PRIV extern const struct sr_dev_driver *sr_driver_list__start[];
+SR_PRIV extern const struct sr_dev_driver *sr_driver_list__stop[];
 
 /** @private
  * Initialize the driver list in a fresh libsigrok context.
@@ -49,8 +45,8 @@ SR_API void sr_drivers_init(struct sr_context *ctx)
 
 	array = g_array_new(TRUE, FALSE, sizeof(struct sr_dev_driver *));
 #ifdef HAVE_DRIVERS
-	for (struct sr_dev_driver **drivers = &__start_sr_driver_list;
-	     drivers < &__stop_sr_driver_list; drivers++)
+	for (const struct sr_dev_driver **drivers = sr_driver_list__start + 1;
+	     drivers < sr_driver_list__stop; drivers++)
 		g_array_append_val(array, *drivers);
 #endif
 	ctx->driver_list = (struct sr_dev_driver **)array->data;