[PATCH] Add simplistic reimplementation of strcasestr to compat library

[PATCH] Add simplistic reimplementation of strcasestr to compat library

[Dirk Hohndel]

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

Re: [PATCH] Add simplistic reimplementation of strcasestr to compat library

[Tomas Carnecky]

On 4/13/10 6:10 AM, Dirk Hohndel wrote:
>
> 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.

Your patch is missing the part where it adds -DHAVE_STRCASESTR=.. to 
CONFIGURE_C{XX,}FLAGS.

And I still have to figure out the licencing of my patch (need to wait 
for the original author to respond). So maybe your patch, with the 
missing parts added, is better.

tom

Re: [PATCH] Add simplistic reimplementation of strcasestr to compat library

[Anthony Towns]

On Tue, Apr 13, 2010 at 14:10, Dirk Hohndel <hohndel@infradead.org> wrote:
> +/* 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... */

Dunno if this is a question from the original source, but the answer
if anyone's interested is probably because C doesn't have templates --
you'd ideally like to have it treated as:

    char *strcasestr(char *haystack, const char *needle);

for when you're doing a search and replace on the needle (say), and:

    const char *strcasestr(const char *haystack, const char *needle);

for when you're doing a search for the needle in something you can't
modify. But C isn't clever enough to let you say that with just one
function (and no fancy #defines), so you have to drop some of the
typechecking with the (char*) cast on the return value if you want to
handle both use cases, without the compiler complaining about
const->non-const conversions in otherwise correct code in one case or
the other.

Cheers,
aj

-- 
Anthony Towns <aj@erisian.com.au>

Re: [PATCH] Add simplistic reimplementation of strcasestr to compat library

[Dirk Hohndel]

On Tue, 13 Apr 2010 15:59:24 +1000, Anthony Towns <aj@erisian.com.au> wrote:
> On Tue, Apr 13, 2010 at 14:10, Dirk Hohndel <hohndel@infradead.org> wrote:
> > +/* 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... */
> 
> Dunno if this is a question from the original source, but the answer

No, that was me being puzzled :-)

> if anyone's interested is probably because C doesn't have templates --
> you'd ideally like to have it treated as:
> 
>     char *strcasestr(char *haystack, const char *needle);
> 
> for when you're doing a search and replace on the needle (say), and:
> 
>     const char *strcasestr(const char *haystack, const char *needle);
> 
> for when you're doing a search for the needle in something you can't
> modify. But C isn't clever enough to let you say that with just one
> function (and no fancy #defines), so you have to drop some of the
> typechecking with the (char*) cast on the return value if you want to
> handle both use cases, without the compiler complaining about
> const->non-const conversions in otherwise correct code in one case or
> the other.

That makes sense. Thanks

/D

-- 
Dirk Hohndel
Intel Open Source Technology Center