dtc: Simpler interface to source file management

This patch cleans up our handling of input files, particularly dts
source files, but also (to an extent) other input files such as those
used by /incbin/ and those used in -I dtb and -I fs modes.

We eliminate the current clunky mechanism which combines search paths
(which we don't actually use at present) with the open relative to
current source file behaviour, which we do.

Instead there's a single srcfile_relative_open() entry point for
callers which opens a new input file relative to the current source
file (which the srcpos code tracks internally).  It doesn't currently
do search paths, but we can add that later without messing with the
callers, by drawing the search path from a global (which makes sense
anyway, rather than shuffling it around the rest of the processing
code).

That suffices for non-dts input files.  For the actual dts files,
srcfile_push() and srcfile_pop() wrappers open the file while also
keeping track of it as the current source file for future opens.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 68 insertions, 83 deletions

diff --git a/srcpos.c b/srcpos.c
index 8bb0c02..f08c1c3 100644
--- a/srcpos.c
+++ b/srcpos.c
@@ -25,117 +25,102 @@
 #include "srcpos.h"
 
 
-/*
- * Like yylineno, this is the current open file pos.
- */
-struct dtc_file *srcpos_file;
+static char *dirname(const char *path)
+{
+	const char *slash = strrchr(path, '/');
 
-/*
- * The empty source position.
- */
+	if (slash) {
+		int len = slash - path;
+		char *dir = xmalloc(len + 1);
 
-struct dtc_file dtc_empty_file = {
-	.dir = NULL,
-	.name = "<no file>",
-	.file = NULL
-};
+		memcpy(dir, path, len);
+		dir[len] = '\0';
+		return dir;
+	}
+	return NULL;
+}
 
-srcpos srcpos_empty = {
-	.first_line = 0,
-	.first_column = 0,
-	.last_line = 0,
-	.last_column = 0,
-	.file = &dtc_empty_file
-};
+struct srcfile_state *current_srcfile; /* = NULL */
 
+/* Detect infinite include recursion. */
+#define MAX_SRCFILE_DEPTH     (100)
+static int srcfile_depth; /* = 0 */
 
-static int
-dtc_open_one(struct dtc_file *file, const char *search, const char *fname)
+FILE *srcfile_relative_open(const char *fname, char **fullnamep)
 {
+	FILE *f;
 	char *fullname;
 
-	if (search) {
-		fullname = xmalloc(strlen(search) + strlen(fname) + 2);
-
-		strcpy(fullname, search);
-		strcat(fullname, "/");
-		strcat(fullname, fname);
+	if (streq(fname, "-")) {
+		f = stdin;
+		fullname = xstrdup("<stdin>");
 	} else {
-		fullname = xstrdup(fname);
+		if (!current_srcfile || !current_srcfile->dir
+		    || (fname[0] == '/'))
+			fullname = xstrdup(fname);
+		else
+			fullname = join_path(current_srcfile->dir, fname);
+
+		f = fopen(fullname, "r");
+		if (!f)
+			die("Couldn't open \"%s\": %s\n", fname,
+			    strerror(errno));
 	}
 
-	file->file = fopen(fullname, "r");
-	if (!file->file) {
+	if (fullnamep)
+		*fullnamep = fullname;
+	else
 		free(fullname);
-		return 0;
-	}
 
-	file->name = fullname;
-	return 1;
+	return f;
 }
 
-
-struct dtc_file *
-dtc_open_file(const char *fname, const struct search_path *search)
+void srcfile_push(const char *fname)
 {
-	static const struct search_path default_search = { NULL, NULL, NULL };
+	struct srcfile_state *srcfile;
 
-	struct dtc_file *file;
-	const char *slash;
+	if (srcfile_depth++ >= MAX_SRCFILE_DEPTH)
+		die("Includes nested too deeply");
 
-	file = xmalloc(sizeof(struct dtc_file));
+	srcfile = xmalloc(sizeof(*srcfile));
 
-	slash = strrchr(fname, '/');
-	if (slash) {
-		char *dir = xmalloc(slash - fname + 1);
-
-		memcpy(dir, fname, slash - fname);
-		dir[slash - fname] = 0;
-		file->dir = dir;
-	} else {
-		file->dir = NULL;
-	}
-
-	if (streq(fname, "-")) {
-		file->name = "stdin";
-		file->file = stdin;
-		return file;
-	}
-
-	if (fname[0] == '/') {
-		file->file = fopen(fname, "r");
-		if (!file->file)
-			goto fail;
+	srcfile->f = srcfile_relative_open(fname, &srcfile->name);
+	srcfile->dir = dirname(srcfile->name);
+	srcfile->prev = current_srcfile;
+	current_srcfile = srcfile;
+}
 
-		file->name = xstrdup(fname);
-		return file;
-	}
+int srcfile_pop(void)
+{
+	struct srcfile_state *srcfile = current_srcfile;
 
-	if (!search)
-		search = &default_search;
+	assert(srcfile);
 
-	while (search) {
-		if (dtc_open_one(file, search->dir, fname))
-			return file;
+	current_srcfile = srcfile->prev;
 
-		if (errno != ENOENT)
-			goto fail;
+	if (fclose(srcfile->f))
+		die("Error closing \"%s\": %s\n", srcfile->name, strerror(errno));
 
-		search = search->next;
-	}
+	/* FIXME: We allow the srcfile_state structure to leak,
+	 * because it could still be referenced from a location
+	 * variable being carried through the parser somewhere.  To
+	 * fix this we could either allocate all the files from a
+	 * table, or use a pool allocator. */
 
-fail:
-	die("Couldn't open \"%s\": %s\n", fname, strerror(errno));
+	return current_srcfile ? 1 : 0;
 }
 
+/*
+ * The empty source position.
+ */
 
-void
-dtc_close_file(struct dtc_file *file)
-{
-	if (fclose(file->file))
-		die("Error closing \"%s\": %s\n", file->name, strerror(errno));
-}
-
+srcpos srcpos_empty = {
+	.first_line = 0,
+	.first_column = 0,
+	.last_line = 0,
+	.last_column = 0,
+	.file = NULL,
+};
 
 srcpos *
 srcpos_copy(srcpos *pos)