Add simplistic reimplementation of strcasestr to compat library

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>

Tested-by: Tomas Carnecky <tom@dbservice.com> (on OpenSolaris snv_134)

4 files changed, 58 insertions, 0 deletions

diff --git a/compat/Makefile.local b/compat/Makefile.local
index 50f6cd19..653fc710 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
diff --git a/compat/compat.h b/compat/compat.h
index d639e0f9..173ef680 100644
--- a/compat/compat.h
+++ b/compat/compat.h
@@ -38,4 +38,8 @@ getdelim (char **lineptr, size_t *n, int delimiter, FILE *fp);
 
 #endif /* !HAVE_GETLINE */
 
+#if !HAVE_STRCASESTR
+char* strcasestr(const char *haystack, const char *needle);
+#endif /* !HAVE_STRCASESTR */
+
 #endif /* NOTMUCH_COMPAT_H */
diff --git a/compat/have_strcasestr.c b/compat/have_strcasestr.c
new file mode 100644
index 00000000..c0fb7629
--- /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 00000000..62a3a545
--- /dev/null
+++ b/compat/strcasestr.c
@@ -0,0 +1,40 @@
+/*
+ * 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. */
+
+#include <string.h>
+
+#include "compat.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;
+}