discover/grub: Improve BLS grub environment variables expansion

[petitboot] / discover / grub2 / blscfg.c

diff --git a/discover/grub2/blscfg.c b/discover/grub2/blscfg.c
index a3813064a0a3daa30d47c168e4a54081e5b2c902..d4754aa363dfa0812d2feb9b7ced5be6e03b7aa9 100644 (file)
--- a/discover/grub2/blscfg.c
+++ b/discover/grub2/blscfg.c
@@ -2,6 +2,7 @@
 #define _GNU_SOURCE
 
 #include <assert.h>
+#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
 #include <dirent.h>
@@ -34,54 +35,106 @@ struct bls_state {
        const char *dtb;
 };
 
+static char *field_append(struct bls_state *state, int type, char *buffer,
+                         char *start, char *end)
+{
+       char *temp = talloc_strndup(state, start, end - start + 1);
+       const char *field = temp;
+
+       if (type == GRUB2_WORD_VAR) {
+               field = script_env_get(state->script, temp);
+               if (!field)
+                       return buffer;
+       }
+
+       if (!buffer)
+               buffer = talloc_strdup(state->opt, field);
+       else
+               buffer = talloc_asprintf_append(buffer, "%s", field);
+
+       return buffer;
+}
+
+static char *expand_field(struct bls_state *state, char *value)
+{
+       char *buffer = NULL;
+       char *start = value;
+       char *end = value;
+       int type = GRUB2_WORD_TEXT;
+
+       while (*value) {
+               if (*value == '$') {
+                       if (start != end) {
+                               buffer = field_append(state, type, buffer,
+                                                     start, end);
+                               if (!buffer)
+                                       return NULL;
+                       }
+
+                       type = GRUB2_WORD_VAR;
+                       start = value + 1;
+               } else if (type == GRUB2_WORD_VAR) {
+                       if (!isalnum(*value) && *value != '_') {
+                               buffer = field_append(state, type, buffer,
+                                                     start, end);
+                               type = GRUB2_WORD_TEXT;
+                               start = value;
+                       }
+               }
+
+               end = value;
+               value++;
+       }
+
+       if (start != end) {
+               buffer = field_append(state, type, buffer,
+                                     start, end);
+               if (!buffer)
+                       return NULL;
+       }
+
+       return buffer;
+}
+
 static void bls_process_pair(struct conf_context *conf, const char *name,
                             char *value)
 {
        struct bls_state *state = conf->parser_info;
        struct discover_boot_option *opt = state->opt;
        struct boot_option *option = opt->option;
-       const char *boot_args;
 
        if (streq(name, "title")) {
-               state->title = talloc_strdup(state, value);
+               state->title = expand_field(state, value);
                return;
        }
 
        if (streq(name, "version")) {
-               state->version = talloc_strdup(state, value);
+               state->version = expand_field(state, value);
                return;
        }
 
        if (streq(name, "machine-id")) {
-               state->machine_id = talloc_strdup(state, value);
+               state->machine_id = expand_field(state, value);
                return;
        }
 
        if (streq(name, "linux")) {
-               state->image = talloc_strdup(state, value);
+               state->image = expand_field(state, value);
                return;
        }
 
        if (streq(name, "initrd")) {
-               state->initrd = talloc_strdup(state, value);
+               state->initrd = expand_field(state, value);
                return;
        }
 
        if (streq(name, "devicetree")) {
-               state->dtb = talloc_strdup(state, value);
+               state->dtb = expand_field(state, value);
                return;
        }
 
        if (streq(name, "options")) {
-               if (value[0] == '$') {
-                       boot_args = script_env_get(state->script, value + 1);
-                       if (!boot_args)
-                               return;
-
-                       option->boot_args = talloc_strdup(opt, boot_args);
-               } else {
-                       option->boot_args = talloc_strdup(opt, value);
-               }
+               option->boot_args = expand_field(state, value);
                return;
        }
 }