make dlerror produce informative results
note that dlerror is specified to be non-thread-safe, so no locking is
performed on the error flag or message aside from the rwlock already
held by dlopen or dlsym. if 2 invocations of dlsym are generating
errors at the same time, they could clobber each other's results, but
the resulting string, albeit corrupt, will still be null-terminated.
any use of dlerror in such a situation could not be expected to give
meaningful results anyway.
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index e0013ec..0533bbb 100644
--- 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__
@@ -142,8 +143,11 @@
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 +409,11 @@
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) {
@@ -634,9 +640,13 @@
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;
}
@@ -694,6 +704,7 @@
return p->deps[i]->base + sym->st_value;
}
errflag = 1;
+ snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
return 0;
}
@@ -720,7 +731,7 @@
{
if (!errflag) return 0;
errflag = 0;
- return "unknown error";
+ return errbuf;
}
int dlclose(void *p)