interposer working

src/Makefile.am

@@ -15,7 +15,7 @@ SUBDIRS = include
 AM_CPPFLAGS = -Iinclude
 
 CLEANFILES = cscope.in.out cscope.out cscope.po.out
-EXTRA_DIST = LICENSE autogen.sh varnishapi.pc.in
+EXTRA_DIST = LICENSE autogen.sh
 
 DISTCHECK_CONFIGURE_FLAGS = \
     --enable-developer-warnings \
@@ -28,12 +28,15 @@ DISTCHECK_CONFIGURE_FLAGS = \
 
 AM_LDFLAGS  = $(AM_LT_LDFLAGS)
 
-lib_LTLIBRARIES = liblongpath.la liblongpath_unsafe.la
+lib_LTLIBRARIES = liblongpath.la liblongpath_unsafe.la liblongpath_interpose.la
 
 liblongpath_includes =		\
-	include/longpath/longpath.h	\
+	include/longpath/longpath.h		\
+	include/longpath/longpath_common.h	\
 	include/longpath/longpath_config.h
 
+## liblongpath
+
 liblongpath_la_CFLAGS = $(AM_CFLAGS) $(PTHREAD_CFLAGS)
 
 liblongpath_la_LDFLAGS = $(AM_LDFLAGS) $(PTHREAD_LDLAGS) \
@@ -43,6 +46,8 @@ liblongpath_la_SOURCES =	\
 	$(liblongpath_includes)	\
 	longpath.c
 
+## liblongpath_unsafe
+
 liblongpath_unsafe_la_CFLAGS = $(AM_CFLAGS) -DUSE_CHDIR_FALLBACK
 
 liblongpath_unsafe_la_LDFLAGS = $(AM_LDFLAGS) \
@@ -50,6 +55,16 @@ liblongpath_unsafe_la_LDFLAGS = $(AM_LDFLAGS) \
 
 liblongpath_unsafe_la_SOURCES = $(liblongpath_la_SOURCES)
 
+## liblongpath_interpose
+
+liblongpath_interpose_la_CFLAGS = $(AM_CFLAGS) -DINTERPOSE \
+	-DOWN_PATH=\"$(libdir)/liblongpath_interpose.so\"
+
+liblongpath_interpose_la_LDFLAGS = $(AM_LDFLAGS) \
+	-export-dynamic -avoid-version -shared -ldl
+
+liblongpath_interpose_la_SOURCES = $(liblongpath_la_SOURCES)
+
 ## TEST - XXX make a proper test directory etc
 
 bin_PROGRAMS = longpath_test longpath_unsafe_test

src/include/longpath/longpath_tbl_functions.h

@@ -68,3 +68,7 @@ FUNCTION(ssize_t, lgetxattr, const char *, const char *, void *, size_t)
 FUNCTION(int, setxattr, const char *, const char *, const void *, size_t, int)
 FUNCTION(int, lsetxattr, const char *, const char *, const void *, size_t, int)
 #endif
+
+#if defined(INTERPOSE) && defined(TRACE)
+FUNCTION(void *, dlopen, const char *, int mode)
+#endif

src/longpath.c

@@ -82,14 +82,18 @@
 # ifdef HAVE__XSTAT
 #  ifdef HAVE_SYS_STAT_IMPL_H
 #   define _SYS_STAT_IMPL_H
+#include <fcntl.h>
+extern int mknod(const char *, mode_t, dev_t);
+extern int stat(const char *, struct stat *);
+extern int lstat(const char *, struct stat *);
+extern int fstatat(int, const char *, struct stat *, int);
 #  else
 #   error This machine probably needs different _xstat handling
 #  endif
-# endif
-#endif
+# endif /* HAVE__XSTAT */
 
-#ifdef INTERPOSE
 # include <longpath/longpath_common.h>
+
 # define real(x)		real_ ## x
 # if defined(_LP64)
 #  define real64(x)		real_ ## x
@@ -102,6 +106,97 @@
 # else
 #  define our64(x)			 x	## 64
 # endif
+
+/*
+ * declaration of real() function pointers
+ */
+# define FUNCTION(type, name, ...) static type (* real(name))(__VA_ARGS__);
+# if ! defined(_LP64)
+#  define FUNCTION64(type, name, ...) static type (* real64(name))(__VA_ARGS__);
+# else
+#  define FUNCTION64(type, name, ...)
+# endif /* _LP64 */
+# include <longpath/longpath_tbl_functions.h>
+# include <longpath/longpath_tbl_functions64.h>
+# undef FUNCTION
+# undef FUNCTION64
+
+# include <dlfcn.h>
+# include <stdio.h>
+# define init_dlsym(fptr, name) do {					\
+		if (! (fptr = dlsym(RTLD_NEXT, #name))) {		\
+			perror("looking up symbol " #name " failed");	\
+			exit(1);					\
+		}							\
+	} while(0)
+
+#ifdef TRACE
+static int tracefd;
+static pid_t pid;
+//static void *my_dl_handle;
+
+#include <unistd.h>
+#endif
+
+/*
+ * init real() function ponters
+ */
+void __attribute__ ((constructor)) longpath_init(void);
+void __attribute__ ((constructor))
+longpath_init(void) {
+# define FUNCTION(type, name, ...) init_dlsym(real(name), name);
+# if ! defined(_LP64)
+#  define FUNCTION64(type, name, ...) init_dlsym(real64(name), name ## 64);
+# else
+#  define FUNCTION64(type, name, ...)
+# endif /* _LP64 */
+# include <longpath/longpath_tbl_functions.h>
+# include <longpath/longpath_tbl_functions64.h>
+# undef FUNCTION
+# undef FUNCTION64
+
+#ifdef TRACE
+	tracefd = real(open)("/tmp/lptrace", O_WRONLY|O_CREAT|O_APPEND, 0600);
+	if (tracefd == -1) {
+		perror("trace file ");
+		exit(1);
+	}
+	pid = getpid();
+#endif /* TRACE */
+}
+
+#ifdef TRACE
+#define TRACELEN 1024
+#define trace(fmt, ...) do {						\
+		char _buf[TRACELEN];					\
+		int _l = snprintf(_buf, TRACELEN, "%d: " fmt, pid, ##__VA_ARGS__); \
+		if ((_l > 0) && (_l < TRACELEN))			\
+			(void)write(tracefd, _buf, _l);			\
+	} while(0)
+
+#include <stdio.h>
+#include <string.h>
+void *
+our(dlopen)(const char *pathname, int mode) {
+	trace("dlopen(%s, 0x%x)\n", pathname ? pathname : "(null)", mode);
+	if (pathname && strstr(pathname, "libc.so")) {
+//		const int nmode = RTLD_GROUP|RTLD_FIRST;
+		trace("returning dlopen(%s, 0x%x)\n", OWN_PATH, mode);
+		return real(dlopen)(OWN_PATH, mode);
+	}
+	if (mode & RTLD_GLOBAL) {
+		const int nmode = RTLD_NOW|RTLD_GLOBAL;
+		void *r;
+		trace("actual dlopen(%s, 0x%x)\n", OWN_PATH, mode|RTLD_PARENT);
+		r = real(dlopen)(pathname, mode|RTLD_PARENT);
+		trace("doing additional dlopen(%s, 0x%x)\n", OWN_PATH, nmode);
+		(void) real(dlopen)(OWN_PATH, nmode);
+		return r;
+	}
+	return real(dlopen)(pathname, mode);
+}
+#endif /* TRACE */
+
 #else /* ! INTERPOSE */
 # include <longpath/longpath.h>
 # define real(x)			 x
@@ -676,7 +771,7 @@ int
 our(chmod)(const char *path, mode_t mode) {
 	int fd;
 	Xfl(path, 0, -1,
-	    fd, real(fchmod), mode);
+	    fd, fchmod, mode);
 	return fd;
 }
 
@@ -1142,7 +1237,7 @@ our(futimesat)(int filedes, const char *path, const struct timeval tv[2]) {
 	tv2ts(&tsp, tv);
 
 	if (path == NULL)
-		return real(futimens)(filedes, tsp);
+		return futimens(filedes, tsp);
 
 	return our(utimensat)(filedes, path, tsp, 0);
 }
@@ -1196,7 +1291,7 @@ our(opendir)(const char *dirname) {
 	if (fd == -1)
 		return NULL;
 
-	return real(fdopendir)(fd);
+	return fdopendir(fd);
 }
 
 #ifdef NEED_CHDIR