ldso: support RTLD_NODELETE and DF_1_NODELETE

Honor the nodelete flags so we don't delete shared library if it's
sticky. This is useful for libpthread if it gets pulled in by a
dlopen'ed library.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

ldso/include/dl-elf.h

@@ -104,13 +104,15 @@ extern void _dl_protect_relro (struct elf_resolve *l);
 # define DT_GNU_HASH_IDX (DT_RELCONT_IDX + 1)
 #endif
 
-extern void _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
-                                   void *debug_addr, DL_LOADADDR_TYPE load_off);
+extern unsigned int _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
+                                           void *debug_addr, DL_LOADADDR_TYPE load_off);
 
 static __always_inline
-void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
-                             void *debug_addr, DL_LOADADDR_TYPE load_off)
+unsigned int __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
+                                     void *debug_addr, DL_LOADADDR_TYPE load_off)
 {
+	unsigned int rtld_flags = 0;
+
 	for (; dpnt->d_tag; dpnt++) {
 		if (dpnt->d_tag < DT_NUM) {
 			dynamic_info[dpnt->d_tag] = dpnt->d_un.d_val;
@@ -138,9 +140,12 @@ void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
 		} else if (dpnt->d_tag < DT_LOPROC) {
 			if (dpnt->d_tag == DT_RELOCCOUNT)
 				dynamic_info[DT_RELCONT_IDX] = dpnt->d_un.d_val;
-			if (dpnt->d_tag == DT_FLAGS_1 &&
-			    (dpnt->d_un.d_val & DF_1_NOW))
-				dynamic_info[DT_BIND_NOW] = 1;
+			if (dpnt->d_tag == DT_FLAGS_1) {
+				if (dpnt->d_un.d_val & DF_1_NOW)
+					dynamic_info[DT_BIND_NOW] = 1;
+				if (dpnt->d_un.d_val & DF_1_NODELETE)
+					rtld_flags |= RTLD_NODELETE;
+			}
 #ifdef __LDSO_GNU_HASH_SUPPORT__
 			if (dpnt->d_tag == DT_GNU_HASH)
 				dynamic_info[DT_GNU_HASH_IDX] = dpnt->d_un.d_ptr;
@@ -167,6 +172,7 @@ void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
 	ADJUST_DYN_INFO(DT_GNU_HASH_IDX, load_off);
 #endif
 #undef ADJUST_DYN_INFO
+	return rtld_flags;
 }
 
 /* Reloc type classes as returned by elf_machine_type_class().

ldso/ldso/dl-elf.c

@@ -337,6 +337,7 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
 	unsigned long *lpnt;
 	unsigned long libaddr;
 	unsigned long minvma = 0xffffffff, maxvma = 0;
+	unsigned int rtld_flags;
 	int i, flags, piclib, infile;
 	ElfW(Addr) relro_addr = 0;
 	size_t relro_size = 0;
@@ -700,7 +701,7 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
 
 	dpnt = (ElfW(Dyn) *) dynamic_addr;
 	_dl_memset(dynamic_info, 0, sizeof(dynamic_info));
-	_dl_parse_dynamic_info(dpnt, dynamic_info, NULL, lib_loadaddr);
+	rtld_flags = _dl_parse_dynamic_info(dpnt, dynamic_info, NULL, lib_loadaddr);
 	/* If the TEXTREL is set, this means that we need to make the pages
 	   writable before we perform relocations.  Do this now. They get set
 	   back again later. */
@@ -732,6 +733,7 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
 	tpnt->st_ino = st.st_ino;
 	tpnt->ppnt = (ElfW(Phdr) *) DL_RELOC_ADDR(tpnt->loadaddr, epnt->e_phoff);
 	tpnt->n_phent = epnt->e_phnum;
+	tpnt->rtld_flags |= rtld_flags;
 
 #if defined(USE_TLS) && USE_TLS
 	if (tlsppnt) {
@@ -991,8 +993,8 @@ char *_dl_strdup(const char *string)
 	return retval;
 }
 
-void _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
-                            void *debug_addr, DL_LOADADDR_TYPE load_off)
+unsigned int _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
+                                    void *debug_addr, DL_LOADADDR_TYPE load_off)
 {
-	__dl_parse_dynamic_info(dpnt, dynamic_info, debug_addr, load_off);
+	return __dl_parse_dynamic_info(dpnt, dynamic_info, debug_addr, load_off);
 }

ldso/libdl/libdl.c

@@ -736,7 +736,7 @@ static int do_dlclose(void *vhandle, int need_fini)
 		_dl_handles = rpnt->next_handle;
 	_dl_if_debug_print("%s: usage count: %d\n",
 			handle->dyn->libname, handle->dyn->usage_count);
-	if (handle->dyn->usage_count != 1) {
+	if (handle->dyn->usage_count != 1 || (handle->dyn->rtld_flags & RTLD_NODELETE)) {
 		handle->dyn->usage_count--;
 		free(handle);
 		return 0;
@@ -744,7 +744,8 @@ static int do_dlclose(void *vhandle, int need_fini)
 	/* OK, this is a valid handle - now close out the file */
 	for (j = 0; j < handle->init_fini.nlist; ++j) {
 		tpnt = handle->init_fini.init_fini[j];
-		if (--tpnt->usage_count == 0) {
+		tpnt->usage_count--;
+		if (tpnt->usage_count == 0 && !(tpnt->rtld_flags & RTLD_NODELETE)) {
 			if ((tpnt->dynamic_info[DT_FINI]
 			     || tpnt->dynamic_info[DT_FINI_ARRAY])
 			 && need_fini