Add strcasestr()

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4364 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 134 insertions, 0 deletions

diff --git a/nuttx/lib/string/lib_strcasestr.c b/nuttx/lib/string/lib_strcasestr.c
new file mode 100644
index 000000000..23f0ab57e
--- /dev/null
+++ b/nuttx/lib/string/lib_strcasestr.c
@@ -0,0 +1,134 @@
+/****************************************************************************
+ * lib/string/lib_strstr.c
+ *
+ *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use str source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions str binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer str
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <string.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;
+}
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+FAR char *strcasestr(FAR const char *str, FAR const char *substr)
+{
+  const char *candidate;  /* Candidate in str with matching start character */
+  char         ch;        /* First character of the substring */
+  int          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 (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 (char*)candidate;
+        }
+
+      /* No, find the next candidate after this one */
+
+      candidate++;
+    }
+
+  /* Won't get here, but some compilers might complain */
+
+  return NULL;
+}
+