add dl_iterate_phdr interface
patches by Alex Caudill (npx). the dynamic-linked version is almost
identical to the final submitted patch; I just added a couple missing
lines for saving the phdr address when the dynamic linker is invoked
directly to run a program, and removed a couple to avoid introducing
another unnecessary type. the static-linked version is based on npx's
draft. it could use some improvements which are contingent on the
startup code saving some additional information for later use.
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index a6dbaf0..13bf16a 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -13,6 +13,7 @@
#include <errno.h>
#include <limits.h>
#include <elf.h>
+#include <link.h>
#include <setjmp.h>
#include <pthread.h>
#include <ctype.h>
@@ -56,6 +57,8 @@
size_t *dynv;
struct dso *next, *prev;
+ Phdr *phdr;
+ int phnum;
int refcnt;
Sym *syms;
uint32_t *hashtab;
@@ -91,6 +94,7 @@
static struct dso *head, *tail, *ldso, *fini_head;
static char *env_path, *sys_path, *r_path;
+static unsigned long long gencnt;
static int ssp_used;
static int runtime;
static int ldd_mode;
@@ -323,6 +327,8 @@
eh->e_phoff = sizeof *eh;
}
ph = (void *)((char *)buf + eh->e_phoff);
+ dso->phdr = ph;
+ dso->phnum = eh->e_phnum;
for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type == PT_DYNAMIC)
dyn = ph->p_vaddr;
@@ -825,18 +831,19 @@
lib->name = lib->shortname = "libc.so";
lib->global = 1;
ehdr = (void *)lib->base;
- find_map_range((void *)(aux[AT_BASE]+ehdr->e_phoff),
- ehdr->e_phnum, ehdr->e_phentsize, lib);
- lib->dynv = (void *)(lib->base + find_dyn(
- (void *)(aux[AT_BASE]+ehdr->e_phoff),
- ehdr->e_phnum, ehdr->e_phentsize));
+ lib->phnum = ehdr->e_phnum;
+ lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
+ find_map_range(lib->phdr, ehdr->e_phnum, ehdr->e_phentsize, lib);
+ lib->dynv = (void *)(lib->base + find_dyn(lib->phdr,
+ ehdr->e_phnum, ehdr->e_phentsize));
decode_dyn(lib);
if (aux[AT_PHDR]) {
size_t interp_off = 0;
size_t tls_image = 0;
/* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
- phdr = (void *)aux[AT_PHDR];
+ app->phdr = phdr = (void *)aux[AT_PHDR];
+ app->phnum = aux[AT_PHNUM];
for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
if (phdr->p_type == PT_PHDR)
app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
@@ -884,6 +891,8 @@
close(fd);
lib->name = ldname;
app->name = argv[0];
+ app->phnum = ehdr->e_phnum;
+ app->phdr = (void *)(app->base + ehdr->e_phoff);
aux[AT_ENTRY] = ehdr->e_entry;
}
if (app->tls_size) {
@@ -907,7 +916,8 @@
/* Attach to vdso, if provided by the kernel */
if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
ehdr = (void *)vdso_base;
- phdr = (void *)(vdso_base + ehdr->e_phoff);
+ vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
+ vdso->phnum = ehdr->e_phnum;
for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
if (phdr->p_type == PT_DYNAMIC)
vdso->dynv = (void *)(vdso_base + phdr->p_offset);
@@ -1068,6 +1078,7 @@
orig_tail = tail;
end:
__release_ptc();
+ if (p) gencnt++;
pthread_rwlock_unlock(&lock);
if (p) do_init_fini(orig_tail);
pthread_setcancelstate(cs, 0);
@@ -1192,6 +1203,32 @@
pthread_rwlock_unlock(&lock);
return res;
}
+
+int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
+{
+ struct dso *current;
+ struct dl_phdr_info info;
+ int ret = 0;
+ for(current = head; current;) {
+ info.dlpi_addr = (uintptr_t)current->base;
+ info.dlpi_name = current->name;
+ info.dlpi_phdr = current->phdr;
+ info.dlpi_phnum = current->phnum;
+ info.dlpi_adds = gencnt;
+ info.dlpi_subs = 0;
+ info.dlpi_tls_modid = current->tls_id;
+ info.dlpi_tls_data = current->tls_image;
+
+ ret = (callback)(&info, sizeof (info), data);
+
+ if (ret != 0) break;
+
+ pthread_rwlock_rdlock(&lock);
+ current = current->next;
+ pthread_rwlock_unlock(&lock);
+ }
+ return ret;
+}
#else
void *dlopen(const char *file, int mode)
{