glibc/elf/dl-main.h
Florian Weimer dad90d5282 elf: Add glibc-hwcaps support for LD_LIBRARY_PATH
This hacks non-power-set processing into _dl_important_hwcaps.
Once the legacy hwcaps handling goes away, the subdirectory
handling needs to be reworked, but it is premature to do this
while both approaches are still supported.

ld.so supports two new arguments, --glibc-hwcaps-prepend and
--glibc-hwcaps-mask.  Each accepts a colon-separated list of
glibc-hwcaps subdirectory names.  The prepend option adds additional
subdirectories that are searched first, in the specified order.  The
mask option restricts the automatically selected subdirectories to
those listed in the option argument.  For example, on systems where
/usr/lib64 is on the library search path,
--glibc-hwcaps-prepend=valgrind:debug causes the dynamic loader to
search the directories /usr/lib64/glibc-hwcaps/valgrind and
/usr/lib64/glibc-hwcaps/debug just before /usr/lib64 is searched.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2020-12-04 09:13:43 +01:00

125 lines
3.7 KiB
C

/* Information collection during ld.so startup.
Copyright (C) 1995-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _DL_MAIN
#define _DL_MAIN
#include <ldsodefs.h>
#include <limits.h>
#include <stdlib.h>
/* Length limits for names and paths, to protect the dynamic linker,
particularly when __libc_enable_secure is active. */
#ifdef NAME_MAX
# define SECURE_NAME_LIMIT NAME_MAX
#else
# define SECURE_NAME_LIMIT 255
#endif
#ifdef PATH_MAX
# define SECURE_PATH_LIMIT PATH_MAX
#else
# define SECURE_PATH_LIMIT 1024
#endif
/* Strings containing colon-separated lists of audit modules. */
struct audit_list
{
/* Array of strings containing colon-separated path lists. Each
audit module needs its own namespace, so pre-allocate the largest
possible list. */
const char *audit_strings[DL_NNS];
/* Number of entries added to audit_strings. */
size_t length;
/* Index into the audit_strings array (for the iteration phase). */
size_t current_index;
/* Tail of audit_strings[current_index] which still needs
processing. */
const char *current_tail;
/* Scratch buffer for returning a name which is part of the strings
in audit_strings. */
char fname[SECURE_NAME_LIMIT];
};
/* This is a list of all the modes the dynamic loader can be in. */
enum rtld_mode
{
rtld_mode_normal, rtld_mode_list, rtld_mode_verify, rtld_mode_trace,
rtld_mode_help,
};
/* Aggregated state information extracted from environment variables
and the ld.so command line. */
struct dl_main_state
{
struct audit_list audit_list;
/* The library search path. */
const char *library_path;
/* Where library_path comes from. LD_LIBRARY_PATH or --library-path. */
const char *library_path_source;
/* The list preloaded objects from LD_PRELOAD. */
const char *preloadlist;
/* The preload list passed as a command argument. */
const char *preloadarg;
/* Additional glibc-hwcaps subdirectories to search first.
Colon-separated list. */
const char *glibc_hwcaps_prepend;
/* Mask for the internal glibc-hwcaps subdirectories.
Colon-separated list. */
const char *glibc_hwcaps_mask;
enum rtld_mode mode;
/* True if any of the debugging options is enabled. */
bool any_debug;
/* True if information about versions has to be printed. */
bool version_info;
};
/* Helper function to invoke _dl_init_paths with the right arguments
from *STATE. */
static inline void
call_init_paths (const struct dl_main_state *state)
{
_dl_init_paths (state->library_path, state->library_path_source,
state->glibc_hwcaps_prepend, state->glibc_hwcaps_mask);
}
/* Print ld.so usage information and exit. */
_Noreturn void _dl_usage (const char *argv0, const char *wrong_option)
attribute_hidden;
/* Print ld.so version information and exit. */
_Noreturn void _dl_version (void) attribute_hidden;
/* Print ld.so --help output and exit. */
_Noreturn void _dl_help (const char *argv0, struct dl_main_state *state)
attribute_hidden;
#endif /* _DL_MAIN */