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 <cy...@suse.com> --- Changes: - make libxl_read_file_contents as internal. - handle tolerant_shriking_file as Ian suggested tools/libxl/libxl_internal.h | 2 ++ tools/libxl/libxl_utils.c | 37 +++++++++++++++++++++++++++++-------- 2 files changed, 31 insertions(+), 8 deletions(-) diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index cdbe28b..0965e08 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -3707,6 +3707,8 @@ static inline void libxl__update_config_vtpm(libxl__gc *gc, void libxl__bitmap_copy_best_effort(libxl__gc *gc, libxl_bitmap *dptr, const libxl_bitmap *sptr); #endif +_hidden int libxl_read_sysfs_file_contents(libxl_ctx *ctx, const char *filename, + void **data_r, int *datalen_r); /* * Local variables: diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c index f6be2d7..dc5465e 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; @@ -364,14 +366,20 @@ int libxl_read_file_contents(libxl_ctx *ctx, const char *filename, rs = fread(data, 1, datalen, f); if (rs != datalen) { - if (ferror(f)) + 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 (rs < datalen && tolerate_shrinking_file) { + datalen = rs; + } else { + LOG(ERROR, "%s changed size while we were reading it", + filename); + goto xe; + } + } else { abort(); - goto xe; + } } } @@ -396,6 +404,19 @@ 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 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel