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ld.so: Introduce struct dl_exception

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This commit separates allocating and raising exceptions.  This
simplifies catching and re-raising them because it is no longer
necessary to make a temporary, on-stack copy of the exception message.
This commit is contained in:
Florian Weimer
2017-08-10 13:40:22 +02:00
parent f87cc2bfba
commit 2449ae7b2d
29 changed files with 529 additions and 239 deletions
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147
elf/dl-error-skeleton.c
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@ -39,10 +39,7 @@
_dl_signal_error. */
struct catch
{
const char **objname; /* Object/File name. */
const char **errstring; /* Error detail filled in here. */
bool *malloced; /* Nonzero if the string is malloced
by the libc malloc. */
struct dl_exception *exception; /* The exception data is stored there. */
volatile int *errcode; /* Return value of _dl_signal_error. */
jmp_buf env; /* longjmp here on error. */
};
@ -60,11 +57,6 @@ static __thread struct catch *catch_hook attribute_tls_model_ie;
static struct catch *catch_hook;
#endif
/* This message we return as a last resort. We define the string in a
variable since we have to avoid freeing it and so have to enable
a pointer comparison. See below and in dlfcn/dlerror.c. */
static const char _dl_out_of_memory[] = "out of memory";
#if DL_ERROR_BOOTSTRAP
/* This points to a function which is called when an continuable error is
received. Unlike the handling of `catch' this function may return.
@ -76,6 +68,41 @@ static const char _dl_out_of_memory[] = "out of memory";
static receiver_fct receiver;
#endif /* DL_ERROR_BOOTSTRAP */
/* Lossage while resolving the program's own symbols is always fatal. */
static void
__attribute__ ((noreturn))
fatal_error (int errcode, const char *objname, const char *occasion,
const char *errstring)
{
char buffer[1024];
_dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
RTLD_PROGNAME,
occasion ?: N_("error while loading shared libraries"),
objname, *objname ? ": " : "",
errstring, errcode ? ": " : "",
(errcode
? __strerror_r (errcode, buffer, sizeof buffer)
: ""));
}
void
_dl_signal_exception (int errcode, struct dl_exception *exception,
const char *occasion)
{
struct catch *lcatch = catch_hook;
if (lcatch != NULL)
{
*lcatch->exception = *exception;
*lcatch->errcode = errcode;
/* We do not restore the signal mask because none was saved. */
__longjmp (lcatch->env[0].__jmpbuf, 1);
}
else
fatal_error (errcode, exception->objname, occasion, exception->errstring);
}
libc_hidden_def (_dl_signal_exception)
void
internal_function
_dl_signal_error (int errcode, const char *objname, const char *occation,
@ -86,65 +113,42 @@ _dl_signal_error (int errcode, const char *objname, const char *occation,
if (! errstring)
errstring = N_("DYNAMIC LINKER BUG!!!");
if (objname == NULL)
objname = "";
if (lcatch != NULL)
{
/* We are inside _dl_catch_error. Return to it. We have to
duplicate the error string since it might be allocated on the
stack. The object name is always a string constant. */
size_t len_objname = strlen (objname) + 1;
size_t len_errstring = strlen (errstring) + 1;
char *errstring_copy = malloc (len_objname + len_errstring);
if (errstring_copy != NULL)
{
/* Make a copy of the object file name and the error string. */
*lcatch->objname = memcpy (__mempcpy (errstring_copy,
errstring, len_errstring),
objname, len_objname);
*lcatch->errstring = errstring_copy;
/* If the main executable is relocated it means the libc's malloc
is used. */
bool malloced = true;
#ifdef SHARED
malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL
&& (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0));
#endif
*lcatch->malloced = malloced;
}
else
{
/* This is better than nothing. */
*lcatch->objname = "";
*lcatch->errstring = _dl_out_of_memory;
*lcatch->malloced = false;
}
_dl_exception_create (lcatch->exception, objname, errstring);
*lcatch->errcode = errcode;
/* We do not restore the signal mask because none was saved. */
__longjmp (lcatch->env[0].__jmpbuf, 1);
}
else
{
/* Lossage while resolving the program's own symbols is always fatal. */
char buffer[1024];
_dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
RTLD_PROGNAME,
occation ?: N_("error while loading shared libraries"),
objname, *objname ? ": " : "",
errstring, errcode ? ": " : "",
(errcode
? __strerror_r (errcode, buffer, sizeof buffer)
: ""));
}
fatal_error (errcode, objname, occation, errstring);
}
libc_hidden_def (_dl_signal_error)
#if DL_ERROR_BOOTSTRAP
void
_dl_signal_cexception (int errcode, struct dl_exception *exception,
const char *occasion)
{
if (__builtin_expect (GLRO(dl_debug_mask)
& ~(DL_DEBUG_STATISTICS|DL_DEBUG_PRELINK), 0))
_dl_debug_printf ("%s: error: %s: %s (%s)\n",
exception->objname, occasion,
exception->errstring, receiver ? "continued" : "fatal");
if (receiver)
{
/* We are inside _dl_receive_error. Call the user supplied
handler and resume the work. The receiver will still be
installed. */
(*receiver) (errcode, exception->objname, exception->errstring);
}
else
_dl_signal_exception (errcode, exception, occasion);
}
void
internal_function
_dl_signal_cerror (int errcode, const char *objname, const char *occation,
@ -167,11 +171,9 @@ _dl_signal_cerror (int errcode, const char *objname, const char *occation,
}
#endif /* DL_ERROR_BOOTSTRAP */
int
internal_function
_dl_catch_error (const char **objname, const char **errstring,
bool *mallocedp, void (*operate) (void *), void *args)
_dl_catch_exception (struct dl_exception *exception,
void (*operate) (void *), void *args)
{
/* We need not handle `receiver' since setting a `catch' is handled
before it. */
@ -184,9 +186,7 @@ _dl_catch_error (const char **objname, const char **errstring,
struct catch c;
/* Don't use an initializer since we don't need to clear C.env. */
c.objname = objname;
c.errstring = errstring;
c.malloced = mallocedp;
c.exception = exception;
c.errcode = &errcode;
struct catch *const old = catch_hook;
@ -197,17 +197,30 @@ _dl_catch_error (const char **objname, const char **errstring,
{
(*operate) (args);
catch_hook = old;
*objname = NULL;
*errstring = NULL;
*mallocedp = false;
*exception = (struct dl_exception) { NULL };
return 0;
}
/* We get here only if we longjmp'd out of OPERATE. _dl_signal_error has
already stored values into *OBJNAME, *ERRSTRING, and *MALLOCEDP. */
/* We get here only if we longjmp'd out of OPERATE.
_dl_signal_exception has already stored values into
*EXCEPTION. */
catch_hook = old;
return errcode;
}
libc_hidden_def (_dl_catch_exception)
int
internal_function
_dl_catch_error (const char **objname, const char **errstring,
bool *mallocedp, void (*operate) (void *), void *args)
{
struct dl_exception exception;
int errorcode = _dl_catch_exception (&exception, operate, args);
*objname = exception.objname;
*errstring = exception.errstring;
*mallocedp = exception.message_buffer == exception.errstring;
return errorcode;
}
libc_hidden_def (_dl_catch_error)
#if DL_ERROR_BOOTSTRAP