From a5d10eb1f587a13a513504ffb5d8e6a8738eee6f Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Mon, 23 Apr 2012 12:03:31 -0400 Subject: 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. --- src/ldso/dynlink.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'src/ldso') diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index e0013ec0..0533bbb2 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -18,6 +18,7 @@ #include static int errflag; +static char errbuf[128]; #ifdef __PIC__ @@ -142,8 +143,11 @@ 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 +409,11 @@ 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) { @@ -634,9 +640,13 @@ 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; } @@ -694,6 +704,7 @@ 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 +731,7 @@ char *dlerror() { if (!errflag) return 0; errflag = 0; - return "unknown error"; + return errbuf; } int dlclose(void *p) -- cgit v1.2.1