simplify dynamic linker startup

instead of creating temp dso objects on the stack and moving them to
the heap if dlopen/dlsym are used, use static objects to begin with,
and just donate them to malloc if we no longer need them.

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 33937e7..226e174 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -443,7 +443,9 @@ void *__dynlink(int argc, char **argv, size_t *got)
        size_t i;
        Phdr *phdr;
        Ehdr *ehdr;
-       struct dso lib, app;
+       static struct dso builtin_dsos[2];
+       struct dso *const app = builtin_dsos+0;
+       struct dso *const lib = builtin_dsos+1;
 
        /* Find aux vector just past environ[] */
        for (i=argc+1; argv[i]; i++)
@@ -471,7 +473,7 @@ void *__dynlink(int argc, char **argv, size_t *got)
                }
        }
 
-       app = (struct dso){
+       *app = (struct dso){
                .base = 0,
                .strings = (void *)(app_dyn[DT_STRTAB]),
                .hashtab = (void *)(app_dyn[DT_HASH]),
@@ -479,10 +481,10 @@ void *__dynlink(int argc, char **argv, size_t *got)
                .dynv = (void *)(phdr->p_vaddr),
                .name = argv[0],
                .global = 1,
-               .next = &lib
+               .next = lib
        };
 
-       lib = (struct dso){
+       *lib = (struct dso){
                .base = (void *)aux[AT_BASE],
                .strings = (void *)(aux[AT_BASE]+lib_dyn[DT_STRTAB]),
                .hashtab = (void *)(aux[AT_BASE]+lib_dyn[DT_HASH]),
@@ -495,39 +497,31 @@ void *__dynlink(int argc, char **argv, size_t *got)
 
        /* Relocate the dynamic linker/libc */
        do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
-               lib_dyn[DT_RELSZ], 2, lib.syms, lib.strings, &app);
+               lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);
        do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_RELA]),
-               lib_dyn[DT_RELASZ], 3, lib.syms, lib.strings, &app);
+               lib_dyn[DT_RELASZ], 3, lib->syms, lib->strings, app);
 
        /* 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),
+       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;
+       head = tail = app;
+       libc = lib;
+       app->next = 0;
        load_deps(head);
 
        make_global(head);
        reloc_all(head->next);
        reloc_all(head);
 
-       if (rtld_used) {
-               runtime = 1;
-               head->next->prev = malloc(sizeof *head);
-               *head->next->prev = *head;
-               head = head->next->prev;
-               libc->prev->next = malloc(sizeof *libc);
-               *libc->prev->next = *libc;
-               libc = libc->prev->next;
-               if (libc->next) libc->next->prev = libc;
-               if (tail == &lib) tail = libc;
-       } else {
+       runtime = 1;
+       if (!rtld_used) {
                free_all(head);
                free(sys_path);
+               reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos);
        }
 
        errno = 0;