Thread (20 messages) 20 messages, 8 authors, 2016-01-11

Re: [PATCH v1 1/8] lib/string: introduce match_string() helper

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: 2016-01-11 14:59:38
Also in: lkml

On Sat, 2016-01-09 at 13:57 +0200, Andy Shevchenko wrote:
On Sat, Jan 9, 2016 at 3:12 AM, Sergey Senozhatsky
[off-list ref] wrote:
quoted
Andy Shevchenko wrote:
[..]
quoted
quoted
strncmp() case seems to be quite common.
Like I answered to Rasmus, please, provide real examples.
[..]
quoted
quoted
int nmatch_string(array, array_size, string, string_len)
{
      do {
              strncmp();
      } while ();
}

int match_string(array, array_size, string)
{
      return nmatch_string(array, array_size, string,
strlen(string));
}
See above.
after some quick and inaccurate grepping, well, probably you're
right - not worth it.
Good grep anyway, it clearly shows that there is hard to generalize
which limit to use: a) length of a first argument / item from a list,
b) length of a second argument or a constant.
quoted
arch/mips/bcm63xx/boards/board_bcm963xx.c  void __init
board_prom_init(void)
net/irda/irnet/irnet_irda.c   irnet_dname_to_daddr()
arch/powerpc/sysdev/ppc4xx_cpm.c static ssize_t cpm_idle_store()
arch/x86/ras/mce_amd_inj.c static int __set_inj
drivers/hwtracing/intel_th/msu.c mode_store
drivers/pci/pcie/aer/ecrc.c void pcie_ecrc_get_policy
drivers/pci/pcie/aspm.c pcie_aspm_set_policy
drivers/scsi/aic7xxx/aic7xxx_osm.c aic7xxx_setup
drivers/scsi/aic7xxx/aic79xx_osm.c aic79xx_setup
drivers/scsi/scsi_transport_fc.c static int get_fc_##title##_match
drivers/staging/android/ion/hisilicon/hi6220_ion.c get_type_by_name
drivers/staging/lustre/lustre/lmv/lproc_lmv.c placement_name2policy
drivers/xen/sys-hypervisor.c pmu_mode_store
Thought more about those cases.

If you would like you may introduce something like

int nmatch_string(array, array_size, string, int len)
{
  if (len < 0)
    return match_string();

  for (…) {
    size_t itemlen = (len > 0) ? len : strlen(array[index]);
…
    if (!strncmp(array[index], string, itemlen))
      return index;
  }
  return -EINVAL;
}

And convert existing users where it makes sense.

-- 
Andy Shevchenko [off-list ref]
Intel Finland Oy
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