[CRIU] [PATCH] page-read: add print error in case of bad or corrupted image

[Andrew Vagin]

On Tue, Nov 19, 2013 at 02:14:36PM +0400, Tikhomirov Pavel wrote:
> add it instead of BUG_ON
> we should print error if flag isn't assigned

Why do we need this flag? I think we can always print the error message.

> ---
>  include/page-read.h |    2 ++
>  page-read.c         |   13 ++++++++++---
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/include/page-read.h b/include/page-read.h
> index b19ea69..5ad6325 100644
> --- a/include/page-read.h
> +++ b/include/page-read.h
> @@ -66,4 +66,6 @@ struct page_read {
>  };
>  
>  int open_page_read(int pid, struct page_read *);
> +
> +#define DO_NOT_PRINT_ERROR 1
>  #endif
> diff --git a/page-read.c b/page-read.c
> index 3dde366..43f1b2a 100644
> --- a/page-read.c
> +++ b/page-read.c
> @@ -83,7 +83,7 @@ static void skip_pagemap_pages(struct page_read *pr, unsigned long len)
>  	pr->cvaddr += len;
>  }
>  
> -static int read_pagemap_page_from_parent(struct page_read *pr, unsigned long vaddr, void *buf)
> +static int read_pagemap_page_from_parent(struct page_read *pr, unsigned long vaddr, void *buf, int flags)
>  {
>  	int ret;
>  	struct iovec iov;
> @@ -96,7 +96,12 @@ static int read_pagemap_page_from_parent(struct page_read *pr, unsigned long vad
>  	while (1) {
>  		unsigned long iov_end;
>  
> -		BUG_ON(vaddr < pr->cvaddr);
> +		if (vaddr < pr->cvaddr) {
> +			if (!flags & DO_NOT_PRINT_ERROR)
> +				pr_err("Missing %lu in parent pagemap, current iov: base=%lu,len=%lu\n",
> +					vaddr, (unsigned long)iov.iov_base, iov.iov_len);
> +			return -1;
> +		}
>  		iov_end = (unsigned long)iov.iov_base + iov.iov_len;
>  
>  		if (iov_end <= vaddr) {
> @@ -121,7 +126,9 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, void *bu
>  
>  	if (pr->pe->in_parent) {
>  		pr_debug("\tpr%u Read page %lx from parent\n", pr->id, vaddr);
> -		ret = read_pagemap_page_from_parent(pr->parent, vaddr, buf);
> +		ret = read_pagemap_page_from_parent(pr->parent, vaddr, buf, 0);
> +		if (ret == -1)
> +			return ret;
>  	} else {
>  		pr_debug("\tpr%u Read page %lx from self %lx/%"PRIx64"\n", pr->id,
>  				vaddr, pr->cvaddr, lseek(pr->fd_pg, 0, SEEK_CUR));
> -- 
> 1.7.9.5
> 
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