lib/efi: Add new routines to access efi variables

[petitboot] / lib / efi / efivar.c

diff --git a/lib/efi/efivar.c b/lib/efi/efivar.c
new file mode 100644 (file)
index 0000000..1ac6990
--- /dev/null
+++ b/lib/efi/efivar.c
@@ -0,0 +1,191 @@
+/*
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Copyright (C) 2018 Huaxintong Semiconductor Technology Co.,Ltd. All rights
+ *  reserved.
+ *  Author: Ge Song <ge.song@hxt-semitech.com>
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <linux/fs.h>
+#include <sys/ioctl.h>
+
+#include "efivar.h"
+#include "log/log.h"
+#include "talloc/talloc.h"
+
+static const char *efivarfs_path;
+
+inline void set_efivarfs_path(const char *path)
+{
+       efivarfs_path = path;
+}
+
+inline const char *get_efivarfs_path(void)
+{
+
+       return efivarfs_path;
+}
+
+int efi_del_variable(void *ctx, const char *guidstr,
+               const char *name)
+{
+       int fd, flag, errno_value;
+       int rc = -1;
+       const char *dir;
+       char *path;
+
+       dir = get_efivarfs_path();
+       if (!dir)
+               return -1;
+
+       path = talloc_asprintf(ctx, "%s%s-%s", dir, name, guidstr);
+       if (!path)
+               return -1;
+
+       fd = open(path, O_RDONLY|O_NONBLOCK);
+       if (fd == -1)
+               goto err;
+
+       rc = ioctl(fd, FS_IOC_GETFLAGS, &flag);
+       if (rc == -1)
+               goto err;
+
+       flag &= ~FS_IMMUTABLE_FL;
+       rc = ioctl(fd, FS_IOC_SETFLAGS, &flag);
+       if (rc == -1)
+               goto err;
+
+       close(fd);
+       rc = unlink(path);
+
+err:
+       errno_value = errno;
+       if (fd > 0)
+               close(fd);
+
+       errno = errno_value;
+       return rc;
+}
+
+int efi_get_variable(void *ctx, const char *guidstr, const char *name,
+               uint8_t **data, size_t *data_size, uint32_t *attributes)
+{
+       int fd, errno_value;
+       int rc = -1;
+       void *p, *buf;
+       size_t bufsize = 4096;
+       size_t filesize = 0;
+       ssize_t sz;
+       const char *dir;
+       char *path;
+
+       dir = get_efivarfs_path();
+       if (!dir)
+               return EFAULT;
+
+       path = talloc_asprintf(ctx, "%s%s-%s", dir, name, guidstr);
+       if (!path)
+               return ENOMEM;
+
+       fd = open(path, O_RDONLY|O_NONBLOCK);
+       if (fd < 0)
+               goto err;
+
+       buf = talloc_size(ctx, bufsize);
+       if (!buf)
+               goto err;
+
+       do {
+               p = buf + filesize;
+               sz = read(fd, p, bufsize);
+               if (sz < 0 && errno == EAGAIN) {
+                       continue;
+               } else if (sz == 0) {
+                       break;
+               }
+               filesize += sz;
+       } while (1);
+
+       *attributes = *(uint32_t *)buf;
+       *data = (uint8_t *)(buf + sizeof(uint32_t));
+       *data_size = strlen(buf + sizeof(uint32_t));
+       rc = 0;
+
+err:
+       errno_value = errno;
+       if (fd > 0)
+               close(fd);
+
+       errno = errno_value;
+       return rc;
+}
+
+int efi_set_variable(void *ctx, const char *guidstr, const char *name,
+               uint8_t *data, size_t data_size, uint32_t attributes)
+{
+       int rc = -1, errno_value;
+       int fd = -1;
+       ssize_t len;
+       const char *dir;
+       char *path;
+       void *buf;
+       size_t bufsize;
+       mode_t mask = 0644;
+
+       dir = get_efivarfs_path();
+       if (!dir)
+               return EFAULT;
+
+       path = talloc_asprintf(ctx, "%s%s-%s", dir, name, guidstr);
+       if (!path)
+               return ENOMEM;
+
+       if (!access(path, F_OK)) {
+               rc = efi_del_variable(ctx, guidstr, name);
+               if (rc < 0) {
+                       goto err;
+               }
+       }
+
+       fd = open(path, O_CREAT|O_WRONLY, mask);
+       if (fd < 0)
+               goto err;
+
+       bufsize = sizeof(uint32_t) + data_size;
+       buf = talloc_size(ctx, bufsize);
+       if (!buf)
+               goto err;
+
+       *(uint32_t *)buf = attributes;
+       memcpy(buf + sizeof(uint32_t), data, data_size);
+
+       len = write(fd, buf, bufsize);
+       if ((size_t)len != bufsize)
+               goto err;
+       else
+               rc = 0;
+
+err:
+       errno_value = errno;
+       if (fd > 0)
+               close(fd);
+
+       errno = errno_value;
+       return rc;
+}