diff mbox

support static-only systems

Message ID 1257505762-13819-1-git-send-email-vapier@gentoo.org
State Accepted, archived
Delegated to: stephen hemminger
Headers show

Commit Message

Mike Frysinger Nov. 6, 2009, 11:09 a.m. UTC 
The iptables code supports a "no shared libs" mode where it can be used
without requiring dlfcn related functionality.  This adds similar support
to iproute2 so that it can easily be used on systems like nommu Linux (but
obviously with a few limitations -- no dynamic plugins).

Rather than modify every location that uses dlfcn.h, I hooked the dlfcn.h
header with stub functions when shared library support is disabled.  Then
symbol lookup is done via a local static lookup table (which is generated
automatically at build time) so that internal symbols can be found.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
 .gitignore         |    1 +
 Makefile           |    5 +++++
 genl/Makefile      |   15 +++++++++++++++
 genl/static-syms.c |    6 ++++++
 include/dlfcn.h    |   39 +++++++++++++++++++++++++++++++++++++++
 ip/Makefile        |   16 +++++++++++++++-
 ip/static-syms.c   |    6 ++++++
 tc/Makefile        |   23 +++++++++++++++++++----
 tc/m_ipt.c         |    4 ++++
 tc/static-syms.c   |    6 ++++++
 10 files changed, 116 insertions(+), 5 deletions(-)
 create mode 100644 genl/static-syms.c
 create mode 100644 include/dlfcn.h
 create mode 100644 ip/static-syms.c
 create mode 100644 tc/static-syms.c

Comments

stephen hemminger Nov. 10, 2009, 6:45 p.m. UTC | #1 
On Fri,  6 Nov 2009 06:09:22 -0500
Mike Frysinger <vapier@gentoo.org> wrote:

> The iptables code supports a "no shared libs" mode where it can be used
> without requiring dlfcn related functionality.  This adds similar support
> to iproute2 so that it can easily be used on systems like nommu Linux (but
> obviously with a few limitations -- no dynamic plugins).
> 
> Rather than modify every location that uses dlfcn.h, I hooked the dlfcn.h
> header with stub functions when shared library support is disabled.  Then
> symbol lookup is done via a local static lookup table (which is generated
> automatically at build time) so that internal symbols can be found.
> 
> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
> ---

Both applied thanks.
diff mbox

Patch

diff --git a/.gitignore b/.gitignore
index 5a3d20f..390ffb1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@ 
 Config
+static-syms.h
 .gdbinit
 .gdb_history
 *.o
diff --git a/Makefile b/Makefile
index 74e9d62..77a85c6 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,12 @@  ARPDDIR=/var/lib/arpd
 # Path to db_185.h include
 DBM_INCLUDE:=$(ROOTDIR)/usr/include
 
+SHARED_LIBS = y
+
 DEFINES= -DRESOLVE_HOSTNAMES -DLIBDIR=\"$(LIBDIR)\"
+ifneq ($(SHARED_LIBS),y)
+DEFINES+= -DNO_SHARED_LIBS
+endif
 
 #options if you have a bind>=4.9.4 libresolv (or, maybe, glibc)
 LDLIBS=-lresolv
diff --git a/genl/Makefile b/genl/Makefile
index 6435875..44bb83c 100644
--- a/genl/Makefile
+++ b/genl/Makefile
@@ -1,6 +1,7 @@ 
 GENLOBJ=genl.o
 
 include ../Config
+SHARED_LIBS ?= y
 
 GENLMODULES :=
 GENLMODULES += ctrl.o
@@ -9,8 +10,10 @@  GENLOBJ += $(GENLMODULES)
 
 GENLLIB :=
 
+ifeq ($(SHARED_LIBS),y)
 LDFLAGS += -Wl,-export-dynamic
 LDLIBS  += -lm -ldl
+endif
 
 all: genl
 
@@ -21,3 +24,15 @@  install: all
 
 clean:
 	rm -f $(GENLOBJ) $(GENLLIB) genl
+
+ifneq ($(SHARED_LIBS),y)
+
+genl: static-syms.o
+static-syms.o: static-syms.h
+static-syms.h: $(wildcard *.c)
+	files="$^" ; \
+	for s in `grep -B 3 '\<dlsym' $$files | sed -n '/snprintf/{s:.*"\([^"]*\)".*:\1:;s:%s::;p}'` ; do \
+		sed -n '/'$$s'[^ ]* =/{s:.* \([^ ]*'$$s'[^ ]*\) .*:extern char \1[] __attribute__((weak)); if (!strcmp(sym, "\1")) return \1;:;p}' $$files ; \
+	done > $@
+
+endif
diff --git a/genl/static-syms.c b/genl/static-syms.c
new file mode 100644
index 0000000..1ed3a8a
--- /dev/null
+++ b/genl/static-syms.c
@@ -0,0 +1,6 @@ 
+#include <string.h>
+void *_dlsym(const char *sym)
+{
+#include "static-syms.h"
+	return NULL;
+}
diff --git a/include/dlfcn.h b/include/dlfcn.h
new file mode 100644
index 0000000..b0be5a0
--- /dev/null
+++ b/include/dlfcn.h
@@ -0,0 +1,39 @@ 
+/*
+ * Stub dlfcn implementation for systems that lack shared library support
+ * but obviously can still reference compiled-in symbols.
+ */
+
+#ifndef NO_SHARED_LIBS
+#include_next <dlfcn.h>
+#else
+
+#define RTLD_LAZY 0
+#define _FAKE_DLFCN_HDL (void *)0xbeefcafe
+
+static inline void *dlopen(const char *file, int flag)
+{
+	if (file == NULL)
+		return _FAKE_DLFCN_HDL;
+	else
+		return NULL;
+}
+
+extern void *_dlsym(const char *sym);
+static inline void *dlsym(void *handle, const char *sym)
+{
+	if (handle != _FAKE_DLFCN_HDL)
+		return NULL;
+	return _dlsym(sym);
+}
+
+static inline char *dlerror(void)
+{
+	return NULL;
+}
+
+static inline int dlclose(void *handle)
+{
+	return (handle == _FAKE_DLFCN_HDL) ? 0 : 1;
+}
+
+#endif
diff --git a/ip/Makefile b/ip/Makefile
index 3c185cf..51914e8 100644
--- a/ip/Makefile
+++ b/ip/Makefile
@@ -23,6 +23,20 @@  install: all
 clean:
 	rm -f $(ALLOBJ) $(TARGETS)
 
-LDLIBS += -ldl
+SHARED_LIBS ?= y
+ifeq ($(SHARED_LIBS),y)
 
+LDLIBS += -ldl
 LDFLAGS += -Wl,-export-dynamic
+
+else
+
+ip: static-syms.o
+static-syms.o: static-syms.h
+static-syms.h: $(wildcard *.c)
+	files="$^" ; \
+	for s in `grep -B 3 '\<dlsym' $$files | sed -n '/snprintf/{s:.*"\([^"]*\)".*:\1:;s:%s::;p}'` ; do \
+		sed -n '/'$$s'[^ ]* =/{s:.* \([^ ]*'$$s'[^ ]*\) .*:extern char \1[] __attribute__((weak)); if (!strcmp(sym, "\1")) return \1;:;p}' $$files ; \
+	done > $@
+
+endif
diff --git a/ip/static-syms.c b/ip/static-syms.c
new file mode 100644
index 0000000..1ed3a8a
--- /dev/null
+++ b/ip/static-syms.c
@@ -0,0 +1,6 @@ 
+#include <string.h>
+void *_dlsym(const char *sym)
+{
+#include "static-syms.h"
+	return NULL;
+}
diff --git a/tc/Makefile b/tc/Makefile
index 3ff2535..027055c 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -3,6 +3,7 @@  TCOBJ= tc.o tc_qdisc.o tc_class.o tc_filter.o tc_util.o \
        m_ematch.o emp_ematch.yacc.o emp_ematch.lex.o
 
 include ../Config
+SHARED_LIBS ?= y
 
 TCMODULES :=
 TCMODULES += q_fifo.o
@@ -57,7 +58,12 @@  else
 endif
 
 TCOBJ += $(TCMODULES)
-LDLIBS += -L. -ltc -lm -ldl
+LDLIBS += -L. -ltc -lm
+
+ifeq ($(SHARED_LIBS),y)
+LDLIBS += -ldl
+LDFLAGS += -Wl,-export-dynamic
+endif
 
 TCLIB := tc_core.o
 TCLIB += tc_red.o
@@ -72,9 +78,6 @@  ifeq ($(TC_CONFIG_ATM),y)
   TCSO += q_atm.so
 endif
 
-
-LDFLAGS += -Wl,-export-dynamic
-
 YACC := bison
 LEX := flex
 
@@ -108,3 +111,15 @@  q_atm.so: q_atm.c
 
 %.lex.c: %.l
 	$(LEX) $(LEXFLAGS) -o$@ $<
+
+ifneq ($(SHARED_LIBS),y)
+
+tc: static-syms.o
+static-syms.o: static-syms.h
+static-syms.h: $(wildcard *.c)
+	files="$^" ; \
+	for s in `grep -B 3 '\<dlsym' $$files | sed -n '/snprintf/{s:.*"\([^"]*\)".*:\1:;s:%s::;p}'` ; do \
+		sed -n '/'$$s'[^ ]* =/{s:.* \([^ ]*'$$s'[^ ]*\) .*:extern char \1[] __attribute__((weak)); if (!strcmp(sym, "\1")) return \1;:;p}' $$files ; \
+	done > $@
+
+endif
diff --git a/tc/m_ipt.c b/tc/m_ipt.c
index d17d324..99d9965 100644
--- a/tc/m_ipt.c
+++ b/tc/m_ipt.c
@@ -226,6 +226,10 @@  get_target_name(const char *name)
 	struct iptables_target *m;
 	char path[strlen(lib_dir) + sizeof ("/libipt_.so") + strlen(name)];
 
+#ifdef NO_SHARED_LIBS
+	return NULL;
+#endif
+
 	new_name = malloc(strlen(name) + 1);
 	lname = malloc(strlen(name) + 1);
 	if (new_name)
diff --git a/tc/static-syms.c b/tc/static-syms.c
new file mode 100644
index 0000000..1ed3a8a
--- /dev/null
+++ b/tc/static-syms.c
@@ -0,0 +1,6 @@ 
+#include <string.h>
+void *_dlsym(const char *sym)
+{
+#include "static-syms.h"
+	return NULL;
+}