nuttx/libs/libc/string/lib_strcasestr.c
Alin Jerpelea d6b50a1d3f libs: nxstyle fixes
nxstyle fixes to pass the CI checks

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-03-03 18:52:53 -08:00

124 lines
3.5 KiB
C

/****************************************************************************
* libs/libc/string/lib_strcasestr.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <string.h>
#include <strings.h>
#include <ctype.h>
/****************************************************************************
* Private Functions
****************************************************************************/
static FAR char *strcasechr(FAR const char *s, int uc)
{
register char ch;
if (s)
{
for (; *s; s++)
{
ch = *s;
if (toupper(ch) == uc)
{
return (FAR char *)s;
}
}
}
return NULL;
}
/****************************************************************************
* Public Functions
****************************************************************************/
FAR char *strcasestr(FAR const char *str, FAR const char *substr)
{
FAR const char *candidate; /* Candidate in str with matching start character */
char ch; /* First character of the substring */
size_t len; /* The length of the substring */
/* Special case the empty substring */
len = strlen(substr);
ch = *substr;
if (!ch)
{
/* We'll say that an empty substring matches at the beginning of
* the string
*/
return (FAR char *)str;
}
/* Search for the substring */
candidate = str;
ch = toupper(ch);
for (; ; )
{
/* strcasechr() will return a pointer to the next occurrence of the
* character ch in the string (ignoring case)
*/
candidate = strcasechr(candidate, ch);
if (!candidate || strlen(candidate) < len)
{
/* First character of the substring does not appear in the string
* or the remainder of the string is not long enough to contain the
* substring.
*/
return NULL;
}
/* Check if this is the beginning of a matching substring
* (ignoring case)
*/
if (strncasecmp(candidate, substr, len) == 0)
{
/* Yes.. return the pointer to the first occurrence of the matching
* substring.
*/
return (FAR char *)candidate;
}
/* No, find the next candidate after this one */
candidate++;
}
/* Won't get here, but some compilers might complain. Others might
* complain about this code being unreachable too.
*/
return NULL;
}