[PATCH] lib: fwts_acpi_tables: load tables in deterministically

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

When loading a bunch of ACPI tables we should load them in
some form of deterministic order rather that the random order
that they appear in the directory.  So, load them in on
filename alphasorted order.  This allows us to sanely check the
tables using fwts-test with some sort of determinism.

Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 src/lib/src/fwts_acpi_tables.c |   24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/lib/src/fwts_acpi_tables.c b/src/lib/src/fwts_acpi_tables.c
index eabc2ea..513dfff 100644
--- a/src/lib/src/fwts_acpi_tables.c
+++ b/src/lib/src/fwts_acpi_tables.c
@@ -444,29 +444,34 @@ static uint8_t *fwts_acpi_load_table_from_file(const int fd, size_t *length)
 
 static int fwts_acpi_load_tables_from_file(fwts_framework *fw)
 {
-	DIR *dir;
-	struct dirent *direntry;
+	struct dirent **dir_entries;
 	int count = 0;
+	int i;
 
-	if ((dir = opendir(fw->acpi_table_path)) == NULL) {
+	/*
+ 	 * Read in directory in alphabetical name sorted order
+	 * to ensure the tables are always loaded into memory
+	 * in some form of deterministic order
+	 */
+	if ((count = scandir(fw->acpi_table_path, &dir_entries, 0, alphasort)) < 0) {
 		fwts_log_error(fw, "Cannot open directory '%s' to read ACPI tables.",
 			fw->acpi_table_path);
 		return FWTS_ERROR;
 	}
 
-	while ((direntry = readdir(dir)) != NULL) {
-		if (strstr(direntry->d_name, ".dat")) {
+	for (i = 0; i < count; i++) {
+		if (strstr(dir_entries[i]->d_name, ".dat")) {
 			char path[PATH_MAX];
 			int fd;
+
 			snprintf(path, sizeof(path), "%s/%s",
-				fw->acpi_table_path, direntry->d_name);
+				fw->acpi_table_path, dir_entries[i]->d_name);
 			if ((fd = open(path, O_RDONLY)) >= 0) {
 				uint8_t *table;
 				size_t length;
 				char name[PATH_MAX];
 
-				count++;
-				strcpy(name, direntry->d_name);
+				strcpy(name, dir_entries[i]->d_name);
 				name[strlen(name)-4] = '\0';
 				if ((table = fwts_acpi_load_table_from_file(fd, &length)) != NULL)
 					fwts_acpi_add_table(name, table,
@@ -475,8 +480,9 @@ static int fwts_acpi_load_tables_from_file(fwts_framework *fw)
 			} else
 				fwts_log_error(fw, "Cannot load ACPI table from file '%s'\n", path);
 		}
+		free(dir_entries[i]);
 	}
-	closedir(dir);
+	free(dir_entries);
 
 	if (count == 0) {
 		fwts_log_error(fw, "Could not find any APCI tables in directory '%s'.\n", fw->acpi_table_path);
-- 
1.7.10.4