From: Wei Liu <wei.liu2@citrix.com>
To: Chunyan Liu <cyliu@suse.com>
Cc: jgross@suse.com, wei.liu2@citrix.com, ian.campbell@citrix.com,
george.dunlap@eu.citrix.com, Ian.Jackson@eu.citrix.com,
xen-devel@lists.xen.org, jfehlig@suse.com
Subject: Re: [PATCH V6 2/7] libxl_read_file_contents: add new entry to read sysfs file
Date: Tue, 11 Aug 2015 12:26:55 +0100 [thread overview]
Message-ID: <20150811112655.GE7460@zion.uk.xensource.com> (raw)
In-Reply-To: <1439202928-24813-3-git-send-email-cyliu@suse.com>
On Mon, Aug 10, 2015 at 06:35:23PM +0800, Chunyan Liu wrote:
> Sysfs file has size=4096 but actual file content is less than that.
> Current libxl_read_file_contents will treat it as error when file size
> and actual file content differs, so reading sysfs file content with
> this function always fails.
>
> Add a new entry libxl_read_sysfs_file_contents to handle sysfs file
> specially. It would be used in later pvusb work.
>
> Signed-off-by: Chunyan Liu <cyliu@suse.com>
>
> ---
> Changes:
> - read one more byte to check bigger size problem.
>
> tools/libxl/libxl_internal.h | 2 ++
> tools/libxl/libxl_utils.c | 51 ++++++++++++++++++++++++++++++++++----------
> 2 files changed, 42 insertions(+), 11 deletions(-)
>
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index 6013628..f98f089 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -4001,6 +4001,8 @@ void libxl__bitmap_copy_best_effort(libxl__gc *gc, libxl_bitmap *dptr,
>
> int libxl__count_physical_sockets(libxl__gc *gc, int *sockets);
> #endif
> +_hidden int libxl_read_sysfs_file_contents(libxl_ctx *ctx, const char *filename,
> + void **data_r, int *datalen_r);
Indentation looks wrong.
>
> /*
> * Local variables:
> diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
> index bfc9699..9234efb 100644
> --- a/tools/libxl/libxl_utils.c
> +++ b/tools/libxl/libxl_utils.c
> @@ -322,8 +322,10 @@ out:
> return rc;
> }
>
> -int libxl_read_file_contents(libxl_ctx *ctx, const char *filename,
> - void **data_r, int *datalen_r) {
> +static int libxl_read_file_contents_core(libxl_ctx *ctx, const char *filename,
> + void **data_r, int *datalen_r,
> + bool tolerate_shrinking_file)
> +{
> GC_INIT(ctx);
> FILE *f = 0;
> uint8_t *data = 0;
> @@ -359,20 +361,34 @@ int libxl_read_file_contents(libxl_ctx *ctx, const char *filename,
> datalen = stab.st_size;
>
> if (stab.st_size && data_r) {
> - data = malloc(datalen);
> + data = malloc(datalen + 1);
> if (!data) goto xe;
>
> - rs = fread(data, 1, datalen, f);
> - if (rs != datalen) {
> - if (ferror(f))
> + rs = fread(data, 1, datalen + 1, f);
> + if (rs > datalen) {
> + LOG(ERROR, "%s increased size while we were reading it",
> + filename);
> + goto xe;
> + }
> +
> + if (rs < datalen) {
> + if (ferror(f)) {
> LOGE(ERROR, "failed to read %s", filename);
> - else if (feof(f))
> - LOG(ERROR, "%s changed size while we were reading it",
> - filename);
> - else
> + goto xe;
> + } else if (feof(f)) {
> + if (tolerate_shrinking_file) {
> + datalen = rs;
> + } else {
> + LOG(ERROR, "%s shrunk size while we were reading it",
> + filename);
> + goto xe;
> + }
> + } else {
> abort();
> - goto xe;
> + }
This is a bit bikeshedding, but you can leave "goto xe" out of two `if'
to reduce patch size.
> }
> +
> + data = realloc(data, datalen);
Should check return value of realloc.
The logic of this function reflects what has been discussed so far.
Wei.
> }
>
> if (fclose(f)) {
> @@ -396,6 +412,19 @@ int libxl_read_file_contents(libxl_ctx *ctx, const char *filename,
> return e;
> }
>
> +int libxl_read_file_contents(libxl_ctx *ctx, const char *filename,
> + void **data_r, int *datalen_r)
> +{
> + return libxl_read_file_contents_core(ctx, filename, data_r, datalen_r, 0);
> +}
> +
> +int libxl_read_sysfs_file_contents(libxl_ctx *ctx, const char *filename,
> + void **data_r, int *datalen_r)
> +{
> + return libxl_read_file_contents_core(ctx, filename, data_r, datalen_r, 1);
> +}
> +
> +
> #define READ_WRITE_EXACTLY(rw, zero_is_eof, constdata) \
> \
> int libxl_##rw##_exactly(libxl_ctx *ctx, int fd, \
> --
> 2.1.4
next prev parent reply other threads:[~2015-08-11 11:26 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-10 10:35 [PATCH V6 0/7] xen pvusb toolstack work Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 1/7] libxl: export some functions for pvusb use Chunyan Liu
2015-08-11 11:26 ` Wei Liu
2015-08-10 10:35 ` [PATCH V6 2/7] libxl_read_file_contents: add new entry to read sysfs file Chunyan Liu
2015-08-11 11:26 ` Wei Liu [this message]
2015-08-12 2:37 ` Chun Yan Liu
2015-08-13 9:11 ` Wei Liu
2015-08-10 10:35 ` [PATCH V6 3/7] libxl: add pvusb API Chunyan Liu
2015-08-11 11:27 ` Wei Liu
2015-08-12 2:24 ` Chun Yan Liu
2015-08-13 9:09 ` Wei Liu
2015-08-14 1:49 ` Chun Yan Liu
2015-08-18 2:31 ` Chun Yan Liu
2015-08-31 6:10 ` Chun Yan Liu
2015-09-08 14:17 ` Ian Campbell
2015-09-08 16:52 ` George Dunlap
2015-09-09 7:38 ` Chun Yan Liu
2015-09-17 8:19 ` Chun Yan Liu
2015-09-17 9:54 ` George Dunlap
2015-09-29 17:19 ` Wei Liu
2015-09-17 8:20 ` Chun Yan Liu
2015-09-11 5:42 ` Chun Yan Liu
2015-09-11 13:26 ` Ian Campbell
2015-09-11 13:55 ` Juergen Gross
2015-09-11 14:09 ` Ian Campbell
2015-09-11 14:18 ` Juergen Gross
2015-09-11 14:41 ` Ian Campbell
2015-09-11 15:42 ` Ian Jackson
2015-09-14 3:48 ` Juergen Gross
2015-09-14 10:36 ` George Dunlap
2015-09-14 10:53 ` Juergen Gross
2015-09-14 11:12 ` Ian Jackson
2015-09-14 11:23 ` Juergen Gross
2015-09-14 14:03 ` George Dunlap
2015-09-17 8:24 ` Chun Yan Liu
2015-09-15 8:14 ` Chun Yan Liu
2015-08-10 10:35 ` [PATCH V6 4/7] libxl: add libxl_device_usb_assignable_list API Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 5/7] xl: add pvusb commands Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 6/7] xl: add usb-assignable-list command Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 7/7] domcreate: support pvusb in configuration file Chunyan Liu
2015-08-11 11:27 ` Wei Liu
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