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Enhance --enable-tunables to select tunables frontend at build time

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At the GNU Tools Cauldron 2016, the state of the current tunables
patchset was considered OK with the addition of a way to select the
frontend to be used for the tunables.  That is, to avoid being locked
in to one type of frontend initially, it should be possible to build
tunables with a different frontend with something as simple as a
configure switch.

To that effect, this patch enhances the --enable-tunables option to
accept more values than just 'yes' or 'no'.  The current frontend (and
default when enable-tunables is 'yes') is called 'valstring', to
select the frontend where a single environment variable is set to a
colon-separated value string.  More such frontends can be added in
future.

	* Makeconfig (have-tunables): Check for non-negative instead
	of positive.
	* configure.ac: Add 'valstring' as a valid value for
	--enable-tunables.
	* configure: Regenerate.
	* elf/Makefile (have-tunables): Check for non-negative instead
	of positive.
	(CPPFLAGS-dl-tunables.c): Define TUNABLES_FRONTEND for
	dl-tunables.c.
	* elf/dl-tunables.c (GLIBC_TUNABLES): Define only when
	TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring.
	(tunables_strdup): Likewise.
	(disable_tunables): Likewise.
	(parse_tunables): Likewise.
	(__tunables_init): Process GLIBC_TUNABLES envvar only when.
	TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring.
	* elf/dl-tunables.h (TUNABLES_FRONTEND_valstring): New macro.
	(TUNABLES_FRONTEND_yes): New macro, define as
	TUNABLES_FRONTEND_valstring by default.
	* manual/install.texi: Document new acceptable values for
	--enable-tunables.
	* INSTALL: Regenerate.
This commit is contained in:
Siddhesh Poyarekar
2016-12-31 23:34:04 +05:30
parent 9dd409a5f4
commit 6765d5d34d
9 changed files with 79 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
elf/dl-tunables.c
View File

@ -30,7 +30,9 @@
#define TUNABLES_INTERNAL 1
#include "dl-tunables.h"
#define GLIBC_TUNABLES "GLIBC_TUNABLES"
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
# define GLIBC_TUNABLES "GLIBC_TUNABLES"
#endif
/* Compare environment or tunable names, bounded by the name hardcoded in
glibc. */
@ -48,6 +50,7 @@ is_name (const char *orig, const char *envname)
return false;
}
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
static char *
tunables_strdup (const char *in)
{
@ -70,6 +73,7 @@ tunables_strdup (const char *in)
return out;
}
#endif
static char **
get_next_env (char **envp, char **name, size_t *namelen, char **val)
@ -244,6 +248,7 @@ tunable_initialize (tunable_t *cur, const char *strval)
}
}
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
static void
parse_tunables (char *tunestr)
{
@ -309,6 +314,7 @@ parse_tunables (char *tunestr)
return;
}
}
#endif
static size_t
min_strlen (const char *s)
@ -329,6 +335,7 @@ disable_tunable (tunable_id_t id, char **envp)
if (env_alias != NULL)
tunables_unsetenv (envp, tunable_list[id].env_alias);
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
char *tunable = getenv (GLIBC_TUNABLES);
const char *cmp = tunable_list[id].name;
const size_t len = min_strlen (cmp);
@ -345,6 +352,7 @@ disable_tunable (tunable_id_t id, char **envp)
}
tunable++;
}
#endif
}
/* Disable the glibc.malloc.check tunable in SETUID/SETGID programs unless
@ -375,6 +383,7 @@ __tunables_init (char **envp)
while ((envp = get_next_env (envp, &envname, &len, &envval)) != NULL)
{
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
if (is_name (GLIBC_TUNABLES, envname))
{
char *val = tunables_strdup (envval);
@ -382,6 +391,7 @@ __tunables_init (char **envp)
parse_tunables (val);
continue;
}
#endif
for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
{