[PATCH v3 1/3] tools/bootconfig: Fix to check the write failure correctly

[Masami Hiramatsu]

Fix to check the write(2) failure including partial write
correctly and try to rollback the partial write, because
if there is no BOOTCONFIG_MAGIC string, we can not remove it.

Fixes: 85c46b78da58 ("bootconfig: Add bootconfig magic word for indicating 
bootconfig explicitly")
Suggested-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
 tools/bootconfig/main.c |   27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index eb92027817a7..f7b89a50404c 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -332,6 +332,7 @@ static int delete_xbc(const char *path)
 
 static int apply_xbc(const char *path, const char *xbc_path)
 {
+       struct stat stat;
        u32 size, csum;
        char *buf, *data;
        int ret, fd;
@@ -388,16 +389,26 @@ static int apply_xbc(const char *path, const char 
*xbc_path)
                return fd;
        }
        /* TODO: Ensure the @path is initramfs/initrd image */
+       if (fstat(fd, &stat) < 0) {
+               pr_err("Failed to get the size of %s\n", path);
+               goto out;
+       }
        ret = write(fd, data, size + 8);
-       if (ret < 0) {
+       if (ret < size + 8) {
+               if (ret < 0)
+                       ret = -errno;
                pr_err("Failed to apply a boot config: %d\n", ret);
-               goto out;
+               if (ret < 0)
+                       goto out;
+               goto out_rollback;
        }
        /* Write a magic word of the bootconfig */
        ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
-       if (ret < 0) {
+       if (ret < BOOTCONFIG_MAGIC_LEN) {
+               if (ret < 0)
+                       ret = -errno;
                pr_err("Failed to apply a boot config magic: %d\n", ret);
-               goto out;
+               goto out_rollback;
        }
        ret = 0;
 out:
@@ -405,6 +416,14 @@ static int apply_xbc(const char *path, const char 
*xbc_path)
        free(data);
 
        return ret;
+
+out_rollback:
+       if (ftruncate(fd, stat.st_size) < 0) {
+               ret = -errno;
+               pr_err("Failed to rollback the write error: %d\n", ret);
+               pr_err("The initrd %s may be corrupted. Recommend to 
rebuild.\n", path);
+       }
+       goto out;
 }
 
 static int usage(void)