X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fldso%2Fdynlink.c;h=031e1f0f22f51ecabf8cb39638f7565e6e25c947;hb=2cee45762a1e69444cd711a1a8112a401540081a;hp=35ff9626ae4ee91ae7151e5ddd05463b7ad7b89b;hpb=59ab43f5f8dbd1baf98d3c483c723d155b6f95c8;p=musl

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 35ff9626..031e1f0f 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -139,6 +139,37 @@ static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t
 	}
 }
 
+/* A huge hack: to make up for the wastefulness of shared libraries
+ * needing at least a page of dirty memory even if they have no global
+ * data, we reclaim the gaps at the beginning and end of writable maps
+ * and "donate" them to the heap by setting up minimal malloc
+ * structures and then freeing them. */
+
+static void reclaim(unsigned char *base, size_t start, size_t end)
+{
+	size_t *a, *z;
+	start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
+	end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
+	if (start>end || end-start < 4*sizeof(size_t)) return;
+	a = (size_t *)(base + start);
+	z = (size_t *)(base + end);
+	a[-2] = 1;
+	a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
+	z[1] = 1;
+	free(a);
+}
+
+static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
+{
+	for (; phcnt--; ph=(void *)((char *)ph+phent)) {
+		if (ph->p_type!=PT_LOAD) continue;
+		if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
+		reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
+		reclaim(base, ph->p_vaddr+ph->p_memsz,
+			ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
+	}
+}
+
 static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dynp)
 {
 	Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
@@ -189,7 +220,7 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy
 	 * the length of the file. This is okay because we will not
 	 * use the invalid part; we just need to reserve the right
 	 * amount of virtual address space to map over later. */
-	map = mmap(0, map_len, prot, MAP_PRIVATE, fd, off_start);
+	map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
 	if (map==MAP_FAILED) return 0;
 	base = map - addr_min;
 	ph = (void *)((char *)buf + eh->e_phoff);
@@ -217,6 +248,8 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy
 			}
 		}
 	}
+	if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff),
+		eh->e_phentsize, eh->e_phnum);
 	*lenp = map_len;
 	*basep = base;
 	*dynp = dyn;
@@ -398,6 +431,7 @@ void *__dynlink(int argc, char **argv, size_t *got)
 	size_t lib_dyn[DYN_CNT] = {0};
 	size_t i;
 	Phdr *phdr;
+	Ehdr *ehdr;
 	struct dso lib, app;
 
 	/* Find aux vector just past environ[] */
@@ -456,12 +490,18 @@ void *__dynlink(int argc, char **argv, size_t *got)
 
 	/* At this point the standard library is fully functional */
 
+	reclaim_gaps(app.base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
+	ehdr = (void *)lib.base;
+	reclaim_gaps(lib.base, (void *)(lib.base+ehdr->e_phoff),
+		ehdr->e_phentsize, ehdr->e_phnum);
+
 	head = tail = &app;
 	libc = &lib;
 	app.next = 0;
 	load_deps(head);
 
 	make_global(head);
+	reloc_all(head->next);
 	reloc_all(head);
 
 	if (rtld_used) {
@@ -473,6 +513,7 @@ void *__dynlink(int argc, char **argv, size_t *got)
 		*libc->prev->next = *libc;
 		libc = libc->prev->next;
 		if (libc->next) libc->next->prev = libc;
+		if (tail == &lib) tail = libc;
 	} else {
 		free_all(head);
 		free(sys_path);
@@ -493,6 +534,9 @@ void *dlopen(const char *file, int mode)
 
 	if (setjmp(rtld_fail)) {
 		/* Clean up anything new that was (partially) loaded */
+		if (p->deps) for (i=0; p->deps[i]; i++)
+			if (p->deps[i]->global < 0)
+				p->deps[i]->global = 0;
 		for (p=orig_tail->next; p; p=next) {
 			next = p->next;
 			munmap(p->map, p->map_len);
@@ -506,22 +550,30 @@ void *dlopen(const char *file, int mode)
 	}
 
 	p = load_library(file);
-	if (!p) return 0;
+	if (!p) goto end;
 
 	/* First load handling */
 	if (!p->deps) {
 		load_deps(p);
+		if (p->deps) for (i=0; p->deps[i]; i++)
+			if (!p->deps[i]->global)
+				p->deps[i]->global = -1;
+		if (!p->global) p->global = -1;
 		reloc_all(p);
+		if (p->deps) for (i=0; p->deps[i]; i++)
+			if (p->deps[i]->global < 0)
+				p->deps[i]->global = 0;
+		if (p->global < 0) p->global = 0;
 	}
 
 	if (mode & RTLD_GLOBAL) {
-		for (i=0; p->deps[i]; i++)
+		if (p->deps) for (i=0; p->deps[i]; i++)
 			p->deps[i]->global = 1;
 		p->global = 1;
 	}
 
+end:
 	pthread_rwlock_unlock(&lock);
-
 	return p;
 }
 
@@ -530,7 +582,8 @@ static void *do_dlsym(struct dso *p, const char *s)
 	size_t i;
 	uint32_t h;
 	Sym *sym;
-	if (p == head) return find_sym(head, s, 0);
+	if (p == head || p == RTLD_DEFAULT)
+		return find_sym(head, s, 0);
 	h = hash(s);
 	sym = lookup(s, h, p->syms, p->hashtab, p->strings);
 	if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))