discover/grub2: Add var expansion code

Still todo: splitting.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/discover/grub2/script.c b/discover/grub2/script.c
index 71d6cba..067b0c9 100644
--- a/discover/grub2/script.c
+++ b/discover/grub2/script.c
@@ -1,12 +1,108 @@
 
+#include <sys/types.h>
+#include <regex.h>
+#include <string.h>
+
 #include <talloc/talloc.h>
 
 #include "grub2.h"
 
+struct env_entry {
+	const char		*name;
+	const char		*value;
+	struct list_item	list;
+};
+
+static const char *env_lookup(struct grub2_script *script,
+		const char *name, int name_len)
+{
+	struct env_entry *entry;
+	const char *str;
+
+	str = talloc_strndup(script, name, name_len);
+	printf("%s: %s\n", __func__, str);
+
+	list_for_each_entry(&script->environment, entry, list)
+		if (!strncmp(entry->name, name, name_len))
+			return entry->value;
+
+	return NULL;
+}
+
+static bool expand_word(struct grub2_script *script, struct grub2_word *word)
+{
+	const char *val, *src;
+	char *dest = NULL;
+	regmatch_t match;
+	int n;
+
+	src = word->text;
+
+	n = regexec(&script->var_re, src, 1, &match, 0);
+	if (n == 0)
+		return false;
+
+	val = env_lookup(script, src + match.rm_so,
+				 match.rm_eo - match.rm_so);
+	if (val)
+		val = "";
+
+	dest = talloc_strndup(script, src, match.rm_so);
+	dest = talloc_asprintf_append(dest, "%s%s", val, src + match.rm_eo);
+
+	word->text = dest;
+	return true;
+}
+
+/* iterate through the words in an argv, looking for expansions. If a
+ * word is marked with expand == true, then we process any variable
+ * substitutions.
+ *
+ * Once that's done, we may (if split == true) have to split the word to create
+ * new argv items
+ */
+static void process_expansions(struct grub2_script *script,
+		struct grub2_argv *argv)
+{
+	struct grub2_word *word;
+
+	list_for_each_entry(&argv->words, word, argv_list) {
+		if (!word->expand)
+			continue;
+
+		expand_word(script, word);
+	}
+}
+
+static int script_destroy(void *p)
+{
+	struct grub2_script *script = p;
+	regfree(&script->var_re);
+	return 0;
+}
+
 struct grub2_script *create_script(void *ctx)
 {
 	struct grub2_script *script;
+	int rc;
+
 	script = talloc(ctx, struct grub2_script);
+
+	rc = regcomp(&script->var_re,
+		"\\$\\{?([[:alpha:]][_[:alnum:]]*|[0-9]|[\\?@\\*#])\\}?",
+			REG_EXTENDED);
+	if (rc) {
+		char err[200];
+		regerror(rc, &script->var_re, err, sizeof(err));
+		fprintf(stderr, "RE error %d: %s\n", rc, err);
+		talloc_free(script);
+		return NULL;
+
+	}
+	talloc_set_destructor(script, script_destroy);
+
+	list_init(&script->environment);
+
 	return script;
 }