[PATCH] Add simplistic reimplementation of strcasestr to compat library

[Dirk Hohndel <hohndel@infradead.org>]

While all systems that I have access to support strcasestr, it is
in fact not part of POSIX. So here's a fallback reimplementation
based on POSIX functions.

Signed-off-by: Dirk Hohndel <hohndel@infradead.org>
---
 compat/Makefile.local    |    4 ++++
 compat/have_strcasestr.c |   10 ++++++++++
 compat/strcasestr.c      |   41 +++++++++++++++++++++++++++++++++++++++++
 configure                |   15 +++++++++++++++
 4 files changed, 70 insertions(+), 0 deletions(-)
 create mode 100644 compat/have_strcasestr.c
 create mode 100644 compat/strcasestr.c

diff --git a/compat/Makefile.local b/compat/Makefile.local
index 81e6c70..2a52a14 100644
--- a/compat/Makefile.local
+++ b/compat/Makefile.local
@@ -8,3 +8,7 @@ notmuch_compat_srcs =
 ifneq ($(HAVE_GETLINE),1)
 notmuch_compat_srcs += $(dir)/getline.c $(dir)/getdelim.c
 endif
+
+ifneq ($(HAVE_STRCASESTR),1)
+notmuch_compat_srcs += $(dir)/strcasestr.c 
+endif
\ No newline at end of file
diff --git a/compat/have_strcasestr.c b/compat/have_strcasestr.c
new file mode 100644
index 0000000..c0fb762
--- /dev/null
+++ b/compat/have_strcasestr.c
@@ -0,0 +1,10 @@
+#define _GNU_SOURCE
+#include <strings.h>
+
+int main()
+{
+    char *found;
+    const char *haystack, *needle;
+
+    found = strcasestr(haystack, needle);
+}
diff --git a/compat/strcasestr.c b/compat/strcasestr.c
new file mode 100644
index 0000000..50bc89d
--- /dev/null
+++ b/compat/strcasestr.c
@@ -0,0 +1,41 @@
+/*
+ * slow simplistic reimplementation of strcasestr for systems that
+ * don't include it in their library
+ *
+ * based on a GPL implementation in OpenTTD found under GPL v2
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, version 2.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301, USA.  */
+
+/* Imported into notmuch by Dirk Hohndel - original author unknown. */
+/* the semantic here actually puzzles me:
+   how can haystack be const char * - yet the return value is char *
+   after all, it points to a sub-string of haystack... */
+
+#include <string.h>
+
+char *strcasestr(const char *haystack, const char *needle)
+{
+	size_t hay_len = strlen(haystack);
+	size_t needle_len = strlen(needle);
+	while (hay_len >= needle_len) {
+		if (strncasecmp(haystack, needle, needle_len) == 0) 
+		    return (char *) haystack;
+
+		haystack++;
+		hay_len--;
+	}
+
+	return NULL;
+}
diff --git a/configure b/configure
index 5af7852..023aa40 100755
--- a/configure
+++ b/configure
@@ -310,6 +310,17 @@ else
 fi
 rm -f compat/have_getline
 
+printf "Checking for strcasestr... "
+if ${CC} -o compat/have_strcasestr compat/have_strcasestr.c > /dev/null 2>&1
+then
+    printf "Yes.\n"
+    have_strcasestr=1
+else
+    printf "No (will use our own instead).\n"
+    have_strcasestr=0
+fi
+rm -f compat/have_strcasestr
+
 cat <<EOF
 
 All required packages were found. You may now run the following
@@ -384,6 +395,10 @@ zsh_completion_dir = \$(prefix)/share/zsh/functions/Completion/Unix
 # build its own version)
 HAVE_GETLINE = ${have_getline}
 
+# Whether the strcasestr function is available (if not, then notmuch will
+# build its own version)
+HAVE_STRCASESTR = ${have_strcasestr}
+
 # Flags needed to compile and link against Xapian
 XAPIAN_CXXFLAGS = ${xapian_cxxflags}
 XAPIAN_LDFLAGS = ${xapian_ldflags}
-- 
1.6.6.1


-- 
Dirk Hohndel
Intel Open Source Technology Center