Re: [Qemu-devel] [PATCH v2 01/20] cutils: Provide strchrnul

[Greg Kurz <groug@kaod.org>]

On Thu, 31 May 2018 21:25:56 -0400
Keno Fischer <keno@juliacomputing.com> wrote:

> strchrnul is a GNU extension and thus unavailable on a number of targets.
> In the review for a commit removing strchrnul from 9p, I was asked to
> create a qemu_strchrnul helper to factor out this functionality.
> Do so, and use it in a number of other places in the code base that inlined
> the replacement pattern in a place where strchrnul could be used.
> 
> Signed-off-by: Keno Fischer <keno@juliacomputing.com>
> ---
> 

And possibly we could detect in configure if the host has strchrnul() and
use it, but this optimization can be done later.

I haven't checked if there could be other candidates in the current code
base though. Also, this patch touches some other subsystems, so I'm Cc'ing
to the other maintainers as reported by ./scripts/get_maintainer.pl:

Greg Kurz <groug@kaod.org> (supporter:virtio-9p)
Markus Armbruster <armbru@redhat.com> (supporter:QMP)
"Dr. David Alan Gilbert" <dgilbert@redhat.com> (maintainer:Human Monitor (HMP))
qemu-devel@nongnu.org (open list:All patches CC here)

Anyway,

Acked-by: Greg Kurz <groug@kaod.org>

> Changes since v1: New patch
> 
>  hw/9pfs/9p-local.c    |  2 +-
>  include/qemu/cutils.h |  1 +
>  monitor.c             |  8 ++------
>  util/cutils.c         | 13 +++++++++++++
>  util/qemu-option.c    |  6 +-----
>  util/uri.c            |  6 ++----
>  6 files changed, 20 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index b37b1db..bcf2798 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -65,7 +65,7 @@ int local_open_nofollow(FsContext *fs_ctx, const char *path, int flags,
>          assert(*path != '/');
>  
>          head = g_strdup(path);
> -        c = strchrnul(path, '/');
> +        c = qemu_strchrnul(path, '/');
>          if (*c) {
>              /* Intermediate path element */
>              head[c - path] = 0;
> diff --git a/include/qemu/cutils.h b/include/qemu/cutils.h
> index a663340..bc40c30 100644
> --- a/include/qemu/cutils.h
> +++ b/include/qemu/cutils.h
> @@ -122,6 +122,7 @@ int qemu_strnlen(const char *s, int max_len);
>   * Returns: the pointer originally in @input.
>   */
>  char *qemu_strsep(char **input, const char *delim);
> +const char *qemu_strchrnul(const char *s, int c);
>  time_t mktimegm(struct tm *tm);
>  int qemu_fdatasync(int fd);
>  int fcntl_setfl(int fd, int flag);
> diff --git a/monitor.c b/monitor.c
> index 922cfc0..e1f01c4 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -798,9 +798,7 @@ static int compare_cmd(const char *name, const char *list)
>      p = list;
>      for(;;) {
>          pstart = p;
> -        p = strchr(p, '|');
> -        if (!p)
> -            p = pstart + strlen(pstart);
> +        p = qemu_strchrnul(p, '|');
>          if ((p - pstart) == len && !memcmp(pstart, name, len))
>              return 1;
>          if (*p == '\0')
> @@ -3401,9 +3399,7 @@ static void cmd_completion(Monitor *mon, const char *name, const char *list)
>      p = list;
>      for(;;) {
>          pstart = p;
> -        p = strchr(p, '|');
> -        if (!p)
> -            p = pstart + strlen(pstart);
> +        p = qemu_strchrnul(p, '|');
>          len = p - pstart;
>          if (len > sizeof(cmd) - 2)
>              len = sizeof(cmd) - 2;
> diff --git a/util/cutils.c b/util/cutils.c
> index 0de69e6..6e078b0 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -545,6 +545,19 @@ int qemu_strtou64(const char *nptr, const char **endptr, int base,
>  }
>  
>  /**
> + * Searches for the first occurrence of 'c' in 's', and returns a pointer
> + * to the trailing null byte if none was found.
> + */
> +const char *qemu_strchrnul(const char *s, int c)
> +{
> +    const char *e = strchr(s, c);
> +    if (!e) {
> +        e = s + strlen(s);
> +    }
> +    return e;
> +}
> +
> +/**
>   * parse_uint:
>   *
>   * @s: String to parse
> diff --git a/util/qemu-option.c b/util/qemu-option.c
> index 58d1c23..54eca12 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -77,11 +77,7 @@ const char *get_opt_value(const char *p, char **value)
>  
>      *value = NULL;
>      while (1) {
> -        offset = strchr(p, ',');
> -        if (!offset) {
> -            offset = p + strlen(p);
> -        }
> -
> +        offset = qemu_strchrnul(p, ',');
>          length = offset - p;
>          if (*offset != '\0' && *(offset + 1) == ',') {
>              length++;
> diff --git a/util/uri.c b/util/uri.c
> index 8624a7a..8bdef84 100644
> --- a/util/uri.c
> +++ b/util/uri.c
> @@ -52,6 +52,7 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/cutils.h"
>  
>  #include "qemu/uri.h"
>  
> @@ -2266,10 +2267,7 @@ struct QueryParams *query_params_parse(const char *query)
>          /* Find the next separator, or end of the string. */
>          end = strchr(query, '&');
>          if (!end) {
> -            end = strchr(query, ';');
> -        }
> -        if (!end) {
> -            end = query + strlen(query);
> +            end = qemu_strchrnul(query, ';');
>          }
>  
>          /* Find the first '=' character between here and end. */