gdb shared library debugging support

[musl] / src / ldso / dynlink.c

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index e0013ec..3f3316a 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -18,6 +18,7 @@
 #include <dlfcn.h>
 
 static int errflag;
+static char errbuf[128];
 
 #ifdef __PIC__
 
@@ -37,15 +38,24 @@ typedef Elf64_Sym Sym;
 #define R_SYM(x) ((x)>>32)
 #endif
 
-struct dso
-{
+struct debug {
+       int ver;
+       void *head;
+       void (*bp)(void);
+       int state;
+       void *base;
+};
+
+struct dso {
+       unsigned char *base;
+       char *name;
+       size_t *dynv;
        struct dso *next, *prev;
+
        int refcnt;
-       size_t *dynv;
        Sym *syms;
        uint32_t *hashtab;
        char *strings;
-       unsigned char *base;
        unsigned char *map;
        size_t map_len;
        dev_t dev;
@@ -54,16 +64,22 @@ struct dso
        char relocated;
        char constructed;
        struct dso **deps;
-       char *name;
        char buf[];
 };
 
+struct __pthread;
+struct __pthread *__pthread_self_init(void);
+
 static struct dso *head, *tail, *libc;
 static char *env_path, *sys_path, *r_path;
 static int rtld_used;
+static int ssp_used;
 static int runtime;
 static jmp_buf rtld_fail;
 static pthread_rwlock_t lock;
+static struct debug debug;
+
+struct debug *_dl_debug_addr = &debug;
 
 #define AUX_CNT 24
 #define DYN_CNT 34
@@ -107,6 +123,7 @@ static void *find_sym(struct dso *dso, const char *s, int need_def)
        void *def = 0;
        if (h==0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
        if (h==0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
+       if (h==0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
        for (; dso; dso=dso->next) {
                Sym *sym;
                if (!dso->global) continue;
@@ -142,8 +159,11 @@ static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t
                        ctx = IS_COPY(type) ? dso->next : dso;
                        sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
                        if (!sym_val && sym->st_info>>4 != STB_WEAK) {
+                               snprintf(errbuf, sizeof errbuf,
+                                       "Error relocating %s: %s: symbol not found",
+                                       dso->name, name);
                                if (runtime) longjmp(rtld_fail, 1);
-                               dprintf(2, "%s: symbol not found\n", name);
+                               dprintf(2, "%s\n", errbuf);
                                _exit(127);
                        }
                        sym_size = sym->st_size;
@@ -405,9 +425,11 @@ static void load_deps(struct dso *p)
                        if (p->dynv[i] != DT_NEEDED) continue;
                        dep = load_library(p->strings + p->dynv[i+1]);
                        if (!dep) {
-                               if (runtime) longjmp(rtld_fail, 1);
-                               dprintf(2, "%s: %m (needed by %s)\n",
+                               snprintf(errbuf, sizeof errbuf,
+                                       "Error loading shared library %s: %m (needed by %s)",
                                        p->strings + p->dynv[i+1], p->name);
+                               if (runtime) longjmp(rtld_fail, 1);
+                               dprintf(2, "%s\n", errbuf);
                                _exit(127);
                        }
                        if (runtime) {
@@ -489,6 +511,10 @@ static void do_init_fini(struct dso *p)
        }
 }
 
+void _dl_debug_state(void)
+{
+}
+
 void *__dynlink(int argc, char **argv)
 {
        size_t *auxv, aux[AUX_CNT] = {0};
@@ -597,6 +623,16 @@ void *__dynlink(int argc, char **argv)
         * all memory used by the dynamic linker. */
        runtime = 1;
 
+       for (i=0; app->dynv[i]; i+=2)
+               if (app->dynv[i]==DT_DEBUG)
+                       app->dynv[i+1] = (size_t)&debug;
+       debug.ver = 1;
+       debug.bp = _dl_debug_state;
+       debug.head = head;
+       debug.base = lib->base;
+       debug.state = 0;
+       _dl_debug_state();
+
        do_init_fini(tail);
 
        if (!rtld_used) {
@@ -605,6 +641,8 @@ void *__dynlink(int argc, char **argv)
                reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos);
        }
 
+       if (ssp_used) __pthread_self_init();
+
        errno = 0;
        return (void *)aux[AT_ENTRY];
 }
@@ -634,9 +672,13 @@ void *dlopen(const char *file, int mode)
                tail = orig_tail;
                tail->next = 0;
                p = 0;
+               errflag = 1;
+               goto end;
        } else p = load_library(file);
 
        if (!p) {
+               snprintf(errbuf, sizeof errbuf,
+                       "Error loading shared library %s: %m", file);
                errflag = 1;
                goto end;
        }
@@ -661,6 +703,8 @@ void *dlopen(const char *file, int mode)
                p->global = 1;
        }
 
+       _dl_debug_state();
+
        do_init_fini(tail);
 end:
        pthread_rwlock_unlock(&lock);
@@ -694,6 +738,7 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
                        return p->deps[i]->base + sym->st_value;
        }
        errflag = 1;
+       snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
        return 0;
 }
 
@@ -720,7 +765,7 @@ char *dlerror()
 {
        if (!errflag) return 0;
        errflag = 0;
-       return "unknown error";
+       return errbuf;
 }
 
 int dlclose(void *p)