dtc: Add -i option to support search paths

It is often inconvenient to place device tree files in the same directory
as their includes, or to specify the full path to include files.

An example of this is in U-Boot where we have a .dtsi file for each SOC
type, and this is included by the board .dts file. We need to either use
a mechanism like:

/include/ ARCH_CPU_DTS

with sed or cpp to perform the replacement with the correct path, or
we must specify the full path in the file:

/include/ "../../arch/arm/dts/tegra20.dtsi"

The first option is not desirable since it requires anyone compiling the
file to first pre-process it. The second is not desirable since it
introduces a path which is project-specific into a file which is supposed
to be a hardware description. For example Linux and U-Boot are unlikely to
put these include files in the same place.

It is much more convenient to specify the search patch on the command line
as is done with C pre-processors, for example.

Introduce a -i option to add to the list of search paths used to find
source and include files.

We cannot use -I as it is already in use. Other suggestions welcome.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 85 insertions, 7 deletions

diff --git a/srcpos.c b/srcpos.c
index 36a38e9..3ee523d 100644
--- a/srcpos.c
+++ b/srcpos.c
@@ -24,6 +24,15 @@
 #include "dtc.h"
 #include "srcpos.h"
 
+/* A node in our list of directories to search for source/include files */
+struct search_path {
+	struct search_path *next;	/* next node in list, NULL for end */
+	const char *dirname;		/* name of directory to search */
+};
+
+/* This is the list of directories that we search for source files */
+static struct search_path *search_path_head, **search_path_tail;
+
 
 static char *dirname(const char *path)
 {
@@ -47,6 +56,64 @@ struct srcfile_state *current_srcfile; /* = NULL */
 #define MAX_SRCFILE_DEPTH     (100)
 static int srcfile_depth; /* = 0 */
 
+
+/**
+ * Try to open a file in a given directory.
+ *
+ * If the filename is an absolute path, then dirname is ignored. If it is a
+ * relative path, then we look in that directory for the file.
+ *
+ * @param dirname	Directory to look in, or NULL for none
+ * @param fname		Filename to look for
+ * @param fp		Set to NULL if file did not open
+ * @return allocated filename on success (caller must free), NULL on failure
+ */
+static char *try_open(const char *dirname, const char *fname, FILE **fp)
+{
+	char *fullname;
+
+	if (!dirname || fname[0] == '/')
+		fullname = xstrdup(fname);
+	else
+		fullname = join_path(dirname, fname);
+
+	*fp = fopen(fullname, "r");
+	if (!*fp) {
+		free(fullname);
+		fullname = NULL;
+	}
+
+	return fullname;
+}
+
+/**
+ * Open a file for read access
+ *
+ * If it is a relative filename, we search the full search path for it.
+ *
+ * @param fname	Filename to open
+ * @param fp	Returns pointer to opened FILE, or NULL on failure
+ * @return pointer to allocated filename, which caller must free
+ */
+static char *fopen_any_on_path(const char *fname, FILE **fp)
+{
+	const char *cur_dir = NULL;
+	struct search_path *node;
+	char *fullname;
+
+	/* Try current directory first */
+	assert(fp);
+	if (current_srcfile)
+		cur_dir = current_srcfile->dir;
+	fullname = try_open(cur_dir, fname, fp);
+
+	/* Failing that, try each search path in turn */
+	for (node = search_path_head; !*fp && node; node = node->next)
+		fullname = try_open(node->dirname, fname, fp);
+
+	return fullname;
+}
+
 FILE *srcfile_relative_open(const char *fname, char **fullnamep)
 {
 	FILE *f;
@@ -56,13 +123,7 @@ FILE *srcfile_relative_open(const char *fname, char **fullnamep)
 		f = stdin;
 		fullname = xstrdup("<stdin>");
 	} else {
-		if (!current_srcfile || !current_srcfile->dir
-		    || (fname[0] == '/'))
-			fullname = xstrdup(fname);
-		else
-			fullname = join_path(current_srcfile->dir, fname);
-
-		f = fopen(fullname, "r");
+		fullname = fopen_any_on_path(fname, &f);
 		if (!f)
 			die("Couldn't open \"%s\": %s\n", fname,
 			    strerror(errno));
@@ -119,6 +180,23 @@ int srcfile_pop(void)
 	return current_srcfile ? 1 : 0;
 }
 
+void srcfile_add_search_path(const char *dirname)
+{
+	struct search_path *node;
+
+	/* Create the node */
+	node = xmalloc(sizeof(*node));
+	node->next = NULL;
+	node->dirname = xstrdup(dirname);
+
+	/* Add to the end of our list */
+	if (search_path_tail)
+		*search_path_tail = node;
+	else
+		search_path_head = node;
+	search_path_tail = &node->next;
+}
+
 /*
  * The empty source position.
  */