mirror of git://git.musl-libc.org/musl
cleanup dynamic linker, removing some code duplication
This commit is contained in:
Rich Felker
parent
35620515a8
commit
c82f4a32ec
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@ -286,12 +286,20 @@ static int path_open(const char *name, const char *search)
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}
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}
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static void decode_dyn(struct dso *p)
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{
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size_t dyn[DYN_CNT] = {0};
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decode_vec(p->dynv, dyn, DYN_CNT);
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p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
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p->hashtab = (void *)(p->base + dyn[DT_HASH]);
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p->strings = (void *)(p->base + dyn[DT_STRTAB]);
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}
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static struct dso *load_library(const char *name)
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{
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unsigned char *base, *map;
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size_t dyno, map_len;
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struct dso *p;
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size_t dyn[DYN_CNT] = {0};
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int fd;
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struct stat st;
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@ -365,11 +373,8 @@ static struct dso *load_library(const char *name)
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p->map_len = map_len;
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p->base = base;
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p->dynv = (void *)(base + dyno);
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decode_vec(p->dynv, dyn, DYN_CNT);
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decode_dyn(p);
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p->syms = (void *)(base + dyn[DT_SYMTAB]);
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p->hashtab = (void *)(base + dyn[DT_HASH]);
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p->strings = (void *)(base + dyn[DT_STRTAB]);
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p->dev = st.st_dev;
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p->ino = st.st_ino;
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p->refcnt = 1;
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@ -458,21 +463,24 @@ static void free_all(struct dso *p)
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}
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}
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void *__dynlink(int argc, char **argv, size_t *got)
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static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
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{
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for (; cnt--; ph = (void *)((char *)ph + stride))
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if (ph->p_type == PT_DYNAMIC)
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return ph->p_vaddr;
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return 0;
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}
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void *__dynlink(int argc, char **argv)
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{
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size_t *auxv, aux[AUX_CNT] = {0};
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size_t app_dyn[DYN_CNT] = {0};
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size_t lib_dyn[DYN_CNT] = {0};
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size_t vdso_dyn[DYN_CNT] = {0};
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size_t i;
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Phdr *phdr;
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Ehdr *ehdr;
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size_t *lib_dynv;
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static struct dso builtin_dsos[3];
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struct dso *const app = builtin_dsos+0;
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struct dso *const lib = builtin_dsos+1;
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struct dso *const vdso = builtin_dsos+2;
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size_t vdso_base=0;
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char *env_preload=0;
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/* Find aux vector just past environ[] */
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@ -492,56 +500,31 @@ void *__dynlink(int argc, char **argv, size_t *got)
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env_preload = 0;
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}
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/* The dynamic linker load address is passed by the kernel
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* in the AUX vector, so this is easy. */
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lib->base = (void *)aux[AT_BASE];
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lib->name = "libc.so";
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lib->global = 1;
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ehdr = (void *)lib->base;
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lib->dynv = (void *)(lib->base + find_dyn(
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(void *)(aux[AT_BASE]+ehdr->e_phoff),
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ehdr->e_phnum, ehdr->e_phentsize));
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decode_dyn(lib);
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/* Assume base address of 0 for the main program. This is not
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* valid for PIE code; we will have to search the PHDR to get
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* the correct load address in the PIE case (not yet supported). */
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app->base = 0;
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app->name = argv[0];
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app->global = 1;
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app->dynv = (void *)(app->base + find_dyn(
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(void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
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decode_dyn(app);
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/* Attach to vdso, if provided by the kernel */
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for (i=0; auxv[i]; i+=2) {
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if (auxv[i]==AT_SYSINFO_EHDR) {
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vdso_base = auxv[i+1];
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break;
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}
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}
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/* Find the dynamic linker's DYNAMIC section and decode it */
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ehdr = (void *)aux[AT_BASE];
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phdr = (void *)(aux[AT_BASE] + ehdr->e_phoff);
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for (i=ehdr->e_phnum; i--; phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
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if (phdr->p_type == PT_DYNAMIC) {
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lib_dynv = (void *)(aux[AT_BASE] + phdr->p_vaddr);
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decode_vec(lib_dynv, lib_dyn, DYN_CNT);
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break;
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}
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}
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/* Find the program image's DYNAMIC section and decode it */
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phdr = (void *)aux[AT_PHDR];
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for (i=aux[AT_PHNUM]; i--; phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
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if (phdr->p_type == PT_DYNAMIC) {
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decode_vec((void *)phdr->p_vaddr, app_dyn, DYN_CNT);
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break;
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}
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}
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*app = (struct dso){
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.base = 0,
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.strings = (void *)(app_dyn[DT_STRTAB]),
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.hashtab = (void *)(app_dyn[DT_HASH]),
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.syms = (void *)(app_dyn[DT_SYMTAB]),
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.dynv = (void *)(phdr->p_vaddr),
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.name = argv[0],
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.global = 1,
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.next = lib
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};
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*lib = (struct dso){
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.base = (void *)aux[AT_BASE],
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.strings = (void *)(aux[AT_BASE]+lib_dyn[DT_STRTAB]),
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.hashtab = (void *)(aux[AT_BASE]+lib_dyn[DT_HASH]),
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.syms = (void *)(aux[AT_BASE]+lib_dyn[DT_SYMTAB]),
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.dynv = lib_dynv,
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.name = "libc.so",
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.global = 1,
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.relocated = 1
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};
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if (vdso_base) {
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size_t vdso_base = auxv[i+1];
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if (auxv[i] != AT_SYSINFO_EHDR) continue;
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ehdr = (void *)vdso_base;
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phdr = (void *)(vdso_base + ehdr->e_phoff);
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for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
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@ -550,40 +533,43 @@ void *__dynlink(int argc, char **argv, size_t *got)
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if (phdr->p_type == PT_LOAD)
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vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
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}
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decode_vec(vdso->dynv, vdso_dyn, DYN_CNT);
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vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]);
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vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]);
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vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]);
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vdso->name = "linux-gate.so.1";
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vdso->global = 1;
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decode_dyn(vdso);
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vdso->prev = lib;
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lib->next = vdso;
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break;
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}
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/* Relocate the dynamic linker/libc */
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do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
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lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);
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do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_RELA]),
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lib_dyn[DT_RELASZ], 3, lib->syms, lib->strings, app);
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/* Initial dso chain consists only of the app. We temporarily
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* append the dynamic linker/libc so we can relocate it, then
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* restore the initial chain in preparation for loading third
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* party libraries (preload/needed). */
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head = tail = app;
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libc = lib;
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app->next = lib;
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reloc_all(lib);
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app->next = 0;
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/* At this point the standard library is fully functional */
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/* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
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/* Donate unused parts of app and library mapping to malloc */
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reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
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ehdr = (void *)lib->base;
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reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
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ehdr->e_phentsize, ehdr->e_phnum);
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head = tail = app;
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libc = lib;
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app->next = 0;
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/* Load preload/needed libraries, add their symbols to the global
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* namespace, and perform all remaining relocations. */
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if (env_preload) load_preload(env_preload);
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load_deps(head);
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make_global(head);
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reloc_all(head->next);
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reloc_all(head);
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load_deps(app);
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make_global(app);
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reloc_all(app);
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/* Switch to runtime mode: any further failures in the dynamic
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* linker are a reportable failure rather than a fatal startup
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* error. If the dynamic loader (dlopen) will not be used, free
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* all memory used by the dynamic linker. */
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runtime = 1;
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if (!rtld_used) {
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free_all(head);
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