compat: add a basename() compatibility function

Some systems such as Windows lack libgen.h so provide a
basename() implementation for cross-platform use.

This introduces the NO_LIBGEN_H construct to the Makefile
and autoconf scripts.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -54,6 +54,8 @@ all::
 #
 # Define NO_MKSTEMPS if you don't have mkstemps in the C library.
 #
+# Define NO_LIBGEN_H if you don't have libgen.h.
+#
 # Define NO_SYS_SELECT_H if you don't have sys/select.h.
 #
 # Define NO_SYMLINK_HEAD if you never want .git/HEAD to be a symbolic link.
@@ -834,6 +836,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_PREAD = YesPlease
 	NO_OPENSSL = YesPlease
 	NO_CURL = YesPlease
+	NO_LIBGEN_H = YesPlease
 	NO_SYMLINK_HEAD = YesPlease
 	NO_IPV6 = YesPlease
 	NO_SETENV = YesPlease
@@ -899,6 +902,11 @@ ifndef CC_LD_DYNPATH
 	endif
 endif
 
+ifdef NO_LIBGEN_H
+	COMPAT_CFLAGS += -DNO_LIBGEN_H
+	COMPAT_OBJS += compat/basename.o
+endif
+
 ifdef NO_CURL
 	BASIC_CFLAGS += -DNO_CURL
 else

compat/basename.c

@@ -0,0 +1,15 @@
+#include "../git-compat-util.h"
+
+/* Adapted from libiberty's basename.c.  */
+char *gitbasename (char *path)
+{
+	const char *base;
+	/* Skip over the disk name in MSDOS pathnames. */
+	if (has_dos_drive_prefix(path))
+		path += 2;
+	for (base = path; *path; path++) {
+		if (is_dir_sep(*path))
+			base = path + 1;
+	}
+	return (char *)base;
+}

config.mak.in

@@ -30,6 +30,7 @@ NEEDS_SSL_WITH_CRYPTO=@NEEDS_SSL_WITH_CRYPTO@
 NO_OPENSSL=@NO_OPENSSL@
 NO_CURL=@NO_CURL@
 NO_EXPAT=@NO_EXPAT@
+NO_LIBGEN_H=@NO_LIBGEN_H@
 NEEDS_LIBICONV=@NEEDS_LIBICONV@
 NEEDS_SOCKET=@NEEDS_SOCKET@
 NO_SYS_SELECT_H=@NO_SYS_SELECT_H@

configure.ac

@@ -627,6 +627,12 @@ AC_SUBST(SNPRINTF_RETURNS_BOGUS)
 ## (in default C library and libraries checked by AC_CHECK_LIB)
 AC_MSG_NOTICE([CHECKS for library functions])
 #
+# Define NO_LIBGEN_H if you don't have libgen.h.
+AC_CHECK_HEADER([libgen.h],
+[NO_LIBGEN_H=],
+[NO_LIBGEN_H=YesPlease])
+AC_SUBST(NO_LIBGEN_H)
+#
 # Define NO_STRCASESTR if you don't have strcasestr.
 GIT_CHECK_FUNC(strcasestr,
 [NO_STRCASESTR=],

git-compat-util.h

@@ -97,6 +97,13 @@
 #include "compat/mingw.h"
 #endif	/* __MINGW32__ */
 
+#ifndef NO_LIBGEN_H
+#include <libgen.h>
+#else
+#define basename gitbasename
+extern char *gitbasename(char *);
+#endif
+
 #ifndef NO_ICONV
 #include <iconv.h>
 #endif