Re: [PATCH v2 02/18] earlycpio.c: Fix the confusing comment of find_cpio_data().

Toshi Kani
2013-08-01T21:59:04Z

On Thu, 2013-08-01 at 15:06 +0800, Tang Chen wrote:
> The comments of find_cpio_data() says:
>
> * @offset: When a matching file is found, this is the offset to the
> * beginning of the cpio. ......
>
> But according to the code,
>
> dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
> nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
> ....
> *offset = (long)nptr - (long)data; /* data is the cpio file */
>
> @offset is the offset of the next file, not the matching file itself.
> This is confused and may cause unnecessary waste of time to debug.
> So fix it.
>
> v1 -> v2:
> As tj suggested, rename @offset to @nextoff which is more clear to
> users. And also adjust the new comments.
>
> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> ---
> lib/earlycpio.c | 27 ++++++++++++++-------------
> 1 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/lib/earlycpio.c b/lib/earlycpio.c
> index 8078ef4..7affac0 100644
> --- a/lib/earlycpio.c
> +++ b/lib/earlycpio.c
> @@ -49,22 +49,23 @@ enum cpio_fields {
>
> /**
> * cpio_data find_cpio_data - Search for files in an uncompressed cpio
> - * @path: The directory to search for, including a slash at the end
> - * @data: Pointer to the the cpio archive or a header inside
> - * @len: Remaining length of the cpio based on data pointer
> - * @offset: When a matching file is found, this is the offset to the
> - * beginning of the cpio. It can be used to iterate through
> - * the cpio to find all files inside of a directory path
> + * @path: The directory to search for, including a slash at the end
> + * @data: Pointer to the the cpio archive or a header inside
> + * @len: Remaining length of the cpio based on data pointer
> + * @nextoff: When a matching file is found, this is the offset from the
> + * beginning of the cpio to the beginning of the next file, not the
> + * matching file itself. It can be used to iterate through the cpio
> + * to find all files inside of a directory path
> *
> - * @return: struct cpio_data containing the address, length and
> - * filename (with the directory path cut off) of the found file.
> - * If you search for a filename and not for files in a directory,
> - * pass the absolute path of the filename in the cpio and make sure
> - * the match returned an empty filename string.
> + * @return: struct cpio_data containing the address, length and
> + * filename (with the directory path cut off) of the found file.
> + * If you search for a filename and not for files in a directory,
> + * pass the absolute path of the filename in the cpio and make sure
> + * the match returned an empty filename string.
> */
>
> struct cpio_data __cpuinit find_cpio_data(const char *path, void *data,

This patch does not apply cleanly. It seems that your branch does not
have 0db0628d90125193280eabb501c94feaf48fa9ab.

Thanks,
-Toshi

> - size_t len, long *offset)
> + size_t len, long *nextoff)
> {
> const size_t cpio_header_len = 8*C_NFIELDS - 2;
> struct cpio_data cd = { NULL, 0, "" };
> @@ -124,7 +125,7 @@ struct cpio_data __cpuinit find_cpio_data(const char *path, void *data,
> if ((ch[C_MODE] & 0170000) == 0100000 &&
> ch[C_NAMESIZE] >= mypathsize &&
> !memcmp(p, path, mypathsize)) {
> - *offset = (long)nptr - (long)data;
> + *nextoff = (long)nptr - (long)data;
> if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
> pr_warn(
> "File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",