Add support for building and loading plugins.
A plugin interface makes it possible to add checks in any language. It
also allows these checks to print dts source line information.
Signed-off-by: Andrei Ziureaev <andrei.ziureaev@xxxxxxx>
Signed-off-by: Andrei Ziureaev <andreiziureaev@xxxxxxxxx>
---
Changes in v3:
- plugins have to implement prototypes
- better wording of comments and messages
Changes in v2:
- describe the data model in dtc-plugin.h
- plugins must register with the build system
- the "validate_fn_t" hook can return a status
- specify that minor versions are compatible
- check if plugin_dir is NULL, just in case
- better variable names in register_plugin_info
Makefile | 29 ++++++++++-
dtc-plugin.h | 76 +++++++++++++++++++++++++++
dtc.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++-
dtc.h | 46 +++++++++++++++++
4 files changed, 291 insertions(+), 2 deletions(-)
create mode 100644 dtc-plugin.h
diff --git a/Makefile b/Makefile
index c187d5f..e96bc6e 100644
--- a/Makefile
+++ b/Makefile
@@ -25,6 +25,8 @@ WARNINGS = -Wall -Wpointer-arith -Wcast-qual -Wnested-externs \
-Wstrict-prototypes -Wmissing-prototypes -Wredundant-decls -Wshadow
CFLAGS = -g -Os $(SHAREDLIB_CFLAGS) -Werror $(WARNINGS) $(EXTRA_CFLAGS)
+LDLIBS_dtc += -ldl -export-dynamic
+
BISON = bison
LEX = flex
SWIG = swig
@@ -66,14 +68,17 @@ ifeq ($(HOSTOS),darwin)
SHAREDLIB_EXT = dylib
SHAREDLIB_CFLAGS = -fPIC
SHAREDLIB_LDFLAGS = -fPIC -dynamiclib -Wl,-install_name -Wl,
+PLUGIN_ldflags = -fPIC -dynamiclib
else ifeq ($(HOSTOS),$(filter $(HOSTOS),msys cygwin))
SHAREDLIB_EXT = so
SHAREDLIB_CFLAGS =
SHAREDLIB_LDFLAGS = -shared -Wl,--version-script=$(LIBFDT_version) -Wl,-soname,
+PLUGIN_ldflags = -shared
else
SHAREDLIB_EXT = so
SHAREDLIB_CFLAGS = -fPIC
SHAREDLIB_LDFLAGS = -fPIC -shared -Wl,--version-script=$(LIBFDT_version) -Wl,-soname,
+PLUGIN_ldflags = -fPIC -shared
endif
#
@@ -187,7 +192,29 @@ ifneq ($(MAKECMDGOALS),libfdt)
endif
endif
+#
+# Rules for plugins
+#
+PLUGIN_dir = plugins
+PLUGIN_CLEANFILES += $(PLUGIN_dir)/*.$(SHAREDLIB_EXT)
+PLUGIN_CLEANFILES += $(addprefix $(PLUGIN_dir)/*/,*.o *.$(SHAREDLIB_EXT))
+
+include $(wildcard $(PLUGIN_dir)/*/Makefile.*)
+
+plugins: $(PLUGIN_LIBS)
+
+$(PLUGIN_dir)/%.$(SHAREDLIB_EXT): $(PLUGIN_dir)/%.o
+ @$(VECHO) LD $@
+ $(LINK.c) $(PLUGIN_ldflags) -o $@ $< $(PLUGIN_LDLIBS_$(notdir $*))
+ ln -sf $(patsubst $(PLUGIN_dir)/%,%,$@) $(PLUGIN_dir)/$(notdir $@)
+
+$(PLUGIN_dir)/%.o: $(PLUGIN_dir)/%.c
+ @$(VECHO) CC $@
+ $(CC) $(CPPFLAGS) $(CFLAGS) $(PLUGIN_CFLAGS_$(notdir $*)) -o $@ -c $<
+plugins_clean:
+ @$(VECHO) CLEAN "(plugins)"
+ rm -f $(PLUGIN_CLEANFILES)
#
# Rules for libfdt
@@ -331,7 +358,7 @@ endif
STD_CLEANFILES = *~ *.o *.$(SHAREDLIB_EXT) *.d *.a *.i *.s core a.out vgcore.* \
*.tab.[ch] *.lex.c *.output
-clean: libfdt_clean pylibfdt_clean tests_clean
+clean: libfdt_clean pylibfdt_clean tests_clean plugins_clean
@$(VECHO) CLEAN
rm -f $(STD_CLEANFILES)
rm -f $(VERSION_FILE)
diff --git a/dtc-plugin.h b/dtc-plugin.h
new file mode 100644
index 0000000..ea904bc
--- /dev/null
+++ b/dtc-plugin.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef DTC_PLUGIN_H
+#define DTC_PLUGIN_H
+
+/*
+ * (C) Copyright Arm Holdings. 2020
+ */
+
+#include "dt.h"
+
+struct plugin_arg {
+ char *key; /* A non-empty string */
+ char *value; /* NULL or a non-empty string */
+};
+
+struct plugin_version {
+ int major; /* Incompatible changes */
+ int minor; /* Compatible changes, such as adding a new field
+ * to the end of a struct */
+};
+
+#define DTC_PLUGIN_API_VERSION ((struct plugin_version){ .major = 0, .minor = 0 })
+
+/**
+ * The strictest possible version check.
+ *
+ * @param dtc_ver The version passed by DTC
+ * @return true on success, false on failure
+ */
+static inline bool dtc_plugin_default_version_check(struct plugin_version dtc_ver)
+{
+ struct plugin_version plugin_ver = DTC_PLUGIN_API_VERSION;
+ return dtc_ver.major == plugin_ver.major && dtc_ver.minor == plugin_ver.minor;
+}
+
+/*
+ * Plugins export functionality by implementing one or more of the
+ * functions below. DTC tries to call each function exactly once for
+ * each plugin.
+ *
+ * The typedefs are there for conveniently storing pointers to these
+ * functions.
+ */
+
+/**
+ * Initialize the plugin.
+ *
+ * Called right after the plugin is loaded.
+ *
+ * Every plugin must implement this. At the very least, it should
+ * perform a version check.
+ *
+ * @param dtc_ver DTC's plugin API version
+ * @param argc Length of argv
+ * @param argv Array of plugin arguments
+ * @return 0 on success, or 1 on failure
+ */
+int dtc_init(struct plugin_version dtc_ver, int argc, struct plugin_arg *argv);
+typedef int (*dtc_init_fn_t)(struct plugin_version dtc_ver, int argc,
+ struct plugin_arg *argv);
+
+/**
+ * Validate a device tree.
+ *
+ * Called after DTC's parsing stage, but before the output stage.
+ *
+ * @param dti The unflattened device tree. Implementations can modify
+ * it and "pass it back" to DTC and to subsequent plugins.
+ * The header "dt.h" contains functionality for accessing
+ * "struct dt_info".
+ * @return 1 on a fatal failure, otherwise 0
+ */
+int dtc_validate(struct dt_info *dti);
+typedef int (*dtc_validate_fn_t)(struct dt_info *dti);
+
+#endif /* DTC_PLUGIN_H */
diff --git a/dtc.c b/dtc.c
index bdb3f59..89f67aa 100644
--- a/dtc.c
+++ b/dtc.c
@@ -4,6 +4,7 @@
*/
#include <sys/stat.h>
+#include <dlfcn.h>
#include "dtc.h"
#include "srcpos.h"
@@ -47,7 +48,7 @@ static void fill_fullpaths(struct node *tree, const char *prefix)
/* Usage related data. */
static const char usage_synopsis[] = "dtc [options] <input file>";
-static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:a:fb:i:H:sW:E:@AThv";
+static const char usage_short_opts[] = "qI:O:o:V:d:l:L:R:S:p:a:fb:i:H:sW:E:@AThv";
static struct option const usage_long_opts[] = {
{"quiet", no_argument, NULL, 'q'},
{"in-format", a_argument, NULL, 'I'},
@@ -55,6 +56,8 @@ static struct option const usage_long_opts[] = {
{"out-format", a_argument, NULL, 'O'},
{"out-version", a_argument, NULL, 'V'},
{"out-dependency", a_argument, NULL, 'd'},
+ {"plugin", a_argument, NULL, 'l'},
+ {"plugin-dir", a_argument, NULL, 'L'},
{"reserve", a_argument, NULL, 'R'},
{"space", a_argument, NULL, 'S'},
{"pad", a_argument, NULL, 'p'},
@@ -89,6 +92,13 @@ static const char * const usage_opts_help[] = {
"\t\tasm - assembler source",
"\n\tBlob version to produce, defaults to "stringify(DEFAULT_FDT_VERSION)" (for dtb and asm output)",
"\n\tOutput dependency file",
+ "\n\tLoad a plugin and, optionally, pass it an argument.\n"
+ "\tUsage: -l <plugin name>[,key[,value]]\n"
+ "\t\tplugin name - the name of the shared object without the extension (can contain a path)\n"
+ "\t\tkey - the name of the argument\n"
+ "\t\tvalue - the value of the argument (can be omitted)\n"
+ "\tExample: dtc -l some-plugin,o,out.dts -l some-plugin,help -l another-plugin [...]",
+ "\n\tThe directory in which to search for plugins",
"\n\tMake space for <number> reserve map entries (for dtb and asm output)",
"\n\tMake the blob at least <bytes> long (extra space)",
"\n\tAdd padding to the blob of <bytes> long (extra space)",
@@ -157,6 +167,114 @@ static const char *guess_input_format(const char *fname, const char *fallback)
return guess_type_by_name(fname, fallback);
}
+static struct plugin *get_plugin_with_path(struct plugin_array *plugins,
+ char *path)
+{
+ struct plugin *p;
+ array_for_each(plugins, p)
+ if (strcmp(p->path, path) == 0)
+ return p;
+
+ return NULL;
+}
+
+static void parse_plugin_info(char *arg, const char *plugin_dir, char **path,
+ char **key, char **value)
+{
+ char *name;
+ size_t dirlen;
+ char *tmp;
+ size_t tmplen;
+
+ if (arg == NULL || *arg == '\0' || *arg == ',' || plugin_dir == NULL)
+ return;
+
+ name = strtok(arg, ",");
+
+ dirlen = strlen(plugin_dir);
+ tmplen = dirlen + strlen(name) + strlen(SHAREDLIB_EXT) + 2;
+ tmp = xmalloc(tmplen);
+
+ if (plugin_dir[0] == '\0' || plugin_dir[dirlen - 1] == DIR_SEPARATOR)
+ snprintf(tmp, tmplen, "%s%s%s", plugin_dir,
+ name, SHAREDLIB_EXT);
+ else
+ snprintf(tmp, tmplen, "%s%c%s%s", plugin_dir,
+ DIR_SEPARATOR, name, SHAREDLIB_EXT);
+
+ *path = realpath(tmp, NULL); /* malloc path */
+ if (*path == NULL)
+ die("Couldn't resolve plugin path %s: %s\n", tmp, strerror(errno));
+
+ *key = strtok(NULL, ",");
+ *value = strtok(NULL, "");
+ free(tmp);
+}
+
+static void register_plugin_info(struct plugin_array *plugins, char *arg,
+ const char *plugin_dir)
+{
+ char *path = NULL;
+ char *key = NULL;
+ char *value = NULL;
+ struct plugin *old_plugin;
+ struct plugin new_plugin;
+ struct plugin_arg p_arg;
+
+ parse_plugin_info(arg, plugin_dir, &path, &key, &value);
+
+ if (path == NULL)
+ return;
+
+ p_arg = (struct plugin_arg){ .key = key, .value = value };
+ old_plugin = get_plugin_with_path(plugins, path);
+
+ if (old_plugin == NULL) {
+ new_plugin = (struct plugin){ .path = path, .args = empty_array };
+
+ if (key != NULL)
+ array_add(&new_plugin.args, p_arg);
+
+ array_add(plugins, new_plugin);
+ return;
+ }
+
+ if (key != NULL)
+ array_add(&old_plugin->args, p_arg);
+
+ free(path);
+}
+
+static void load_plugins(struct plugin_array *plugins,
+ const struct string_array *plugin_args,
+ const char *plugin_dir)
+{
+ dtc_init_fn_t init;
+ struct plugin *p;
+ char **arg;
+
+ array_for_each(plugin_args, arg) {
+ register_plugin_info(plugins, *arg, plugin_dir);
+ }
+
+ array_for_each(plugins, p) {
+ p->handle = dlopen(p->path, RTLD_NOW | RTLD_GLOBAL | RTLD_DEEPBIND);
+ if (p->handle == NULL)
+ die("Couldn't load plugin %s: %s\n", p->path, dlerror());
+
+ init = dlsym(p->handle, "dtc_init");
+ if (init == NULL)
+ die("Plugin %s needs to implement dtc_init\n",
+ p->path);
+
+ if (init(DTC_PLUGIN_API_VERSION, p->args.len, p->args.data)) {
+ fprintf(stderr, "DTC: Plugin %s wasn't initialized. Exiting DTC.\n",
+ p->path);
+ exit(1);
+ }
+ }
+}
+
int main(int argc, char *argv[])
{
struct dt_info *dti;
@@ -170,6 +288,10 @@ int main(int argc, char *argv[])
FILE *outf = NULL;
int outversion = DEFAULT_FDT_VERSION;
long long cmdline_boot_cpuid = -1;
+ struct plugin_array plugins = empty_array;
+ struct plugin *plugin;
+ struct string_array plugin_args = empty_array;
+ const char *plugin_dir = "";
quiet = 0;
reservenum = 0;
@@ -194,6 +316,12 @@ int main(int argc, char *argv[])
case 'd':
depname = optarg;
break;
+ case 'l':
+ array_add(&plugin_args, optarg);
+ break;
+ case 'L':
+ plugin_dir = optarg;
+ break;
case 'R':
reservenum = strtol(optarg, NULL, 0);
break;
@@ -283,6 +411,8 @@ int main(int argc, char *argv[])
fprintf(depfile, "%s:", outname);
}
+ load_plugins(&plugins, &plugin_args, plugin_dir);
+
if (inform == NULL)
inform = guess_input_format(arg, "dts");
if (outform == NULL) {
@@ -324,6 +454,15 @@ int main(int argc, char *argv[])
process_checks(force, dti);
+ array_for_each(&plugins, plugin) {
+ dtc_validate_fn_t val = dlsym(plugin->handle, "dtc_validate");
+ if (val && val(dti)) {
+ fprintf(stderr, "DTC: Plugin %s failed to validate the "
+ "device tree. Exiting DTC.\n", plugin->path);
+ exit(1);
+ }
+ }
+
if (auto_label_aliases)
generate_label_tree(dti, "aliases", false);
@@ -365,5 +504,6 @@ int main(int argc, char *argv[])
die("Unknown output format \"%s\"\n", outform);
}
+ /* Leak the plugins and the live tree */
exit(0);
}
diff --git a/dtc.h b/dtc.h
index 286d999..e66e5d1 100644
--- a/dtc.h
+++ b/dtc.h
@@ -22,6 +22,7 @@
#include <fdt.h>
#include "util.h"
+#include "dtc-plugin.h"
#ifdef DEBUG
#define debug(...) printf(__VA_ARGS__)
@@ -340,4 +341,49 @@ void dt_to_yaml(FILE *f, struct dt_info *dti);
struct dt_info *dt_from_fs(const char *dirname);
+/* Plugins */
+
+struct plugin_arg_array {
+ size_t cap;
+ size_t len;
+ struct plugin_arg *data;
+};
+
+struct plugin {
+ const char *path;
+ struct plugin_arg_array args;
+ void *handle;
+};
+
+struct plugin_array {
+ size_t cap;
+ size_t len;
+ struct plugin *data;
+};
+
+struct string_array {
+ size_t cap;
+ size_t len;
+ char **data;
+};
+
+#define empty_array { 0 }
+
+/* Don't add elements to an array while iterating over it */
+#define array_for_each(a, p) \
+ for ((p) = (a)->data; (p) < (a)->data + (a)->len; (p)++)
+
+/* Invalidates all pointers to array members because of the realloc */
+#define array_add(a, p) ( \
+{ \
+ if ((a)->len == (a)->cap) { \
+ (a)->cap = (a)->cap * 2 + 1; \
+ (a)->data = xrealloc((a)->data, (a)->cap * sizeof(p)); \
+ } \
+ (a)->data[(a)->len++] = (p); \
+})
+
+#define DIR_SEPARATOR '/'
+#define SHAREDLIB_EXT ".so"
+
#endif /* DTC_H */
--
2.17.1
