On 09/19/2016 05:45 PM, william.c.roberts@xxxxxxxxx wrote:
> From: William Roberts <william.c.roberts@xxxxxxxxx>
>
> THIS IS WIP...
>
> Rather than using stdio and making copies, just mmap the files
> and use the pointers in place. The affect of this change, is that
> text file load time is now faster than binary load time by 4.7%
> when testing with a file_contexts file from the Android tree. Note
> that the Android doesn't use monstrous regexs.
>
> Times are the average of 3 runs.
>
> BEFORE:
> Text file allocs: 114803
> Text file load time: 0.266101
> Bin file allocs: 93073
> Bin file load time: 0.248757667
>
> AFTER:
> Text file allocs: 103933
> Text file load time: 0.236192667
> Bin file allocs: 87645
> Bin file load time: .247607333
>
> THINGS TO DO:
> 1. What's arm performance like?
> 2. What interfaces to backends are busted by this (if any)?
> 3. Test Android Properties
> 4. Im pretty sure this breaks sefcontext_compile, fix.
> 5. Test with PCRE2 enabled.
> 6. Spell check this message!
> 7. Run checkpatch
>
> Signed-off-by: William Roberts <william.c.roberts@xxxxxxxxx>
> ---
> libselinux/src/label.c | 2 -
> libselinux/src/label_android_property.c | 22 ++---
> libselinux/src/label_file.c | 140 +++++++++++++++++++-------------
> libselinux/src/label_file.h | 66 +++++++++------
> libselinux/src/label_internal.h | 3 +-
> libselinux/src/label_support.c | 79 ++++++++----------
> 6 files changed, 172 insertions(+), 140 deletions(-)
>
> diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
> index 7156825..4dc440e 100644
> --- a/libselinux/src/label_file.c
> +++ b/libselinux/src/label_file.c
> @@ -96,43 +96,64 @@ static int nodups_specs(struct saved_data *data, const char *path)
> return rc;
> }
>
> -static int process_text_file(FILE *fp, const char *prefix,
> - struct selabel_handle *rec, const char *path)
> +static inline struct saved_data *rec_to_data(struct selabel_handle *rec)
> +{
> + return (struct saved_data *)rec->data;
> +}
> +
> +static char *mmap_area_get_line(struct mmap_area *area)
> +{
> + size_t len = area->next_len;
> + if (!len)
> + return NULL;
> +
> + char *start = area->next_addr;
> + char *end = memchr(start, '\n', len);
> +
> + /* the file may not end with a newline */
> + if (!end)
> + end = (char *)area->next_addr + len - 1;
> +
> + *end = '\0';
Couldn't this clobber the last character in the file if the file does
not end with a newline?
> + /* len includes null byte */
> + len = end - start;
> +
> + area->next_len -= len + 1;
> + area->next_addr = ++end;
> + return start;
> +}
> +
> +static int process_text_file(const char *path, const char *prefix,
> + struct selabel_handle *rec)
> {
> int rc;
> - size_t line_len;
> unsigned int lineno = 0;
> - char *line_buf = NULL;
> + char *line_buf;
> + struct mmap_area *areas = rec_to_data(rec)->mmap_areas;
> +
> + /* mmap_area_get_line() and process_line() require mutable string pointers */
> + rc = mprotect(areas->addr, areas->len, PROT_READ | PROT_WRITE);
Just map it with PROT_READ|PROT_WRITE in the beginning.
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