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free: make it NOFORK

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function                                             old     new   delta
parse_cached_kb                                        -      85     +85
free_main                                            580     537     -43
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 85/-43)             Total: 42 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-10-05 14:06:49 +02:00
parent 6e2beb7dfe
commit 318c8114de
2 changed files with 24 additions and 29 deletions
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2
NOFORK_NOEXEC.lst
View File

@ -144,7 +144,7 @@ flash_unlock - hardware
flashcp - hardware
flock - spawner, changes state (file locks), let's play safe and not be noexec
fold - noexec. runner
free - noexec. nofork candidate(struct globals, needs to close /proc/meminfo fd)
free - NOFORK
freeramdisk - noexec. leaks: open+ioctl_or_perror_and_die
fsck - interactive, longterm
fsck.minix - needs ^C

49
procps/free.c
View File

@ -15,7 +15,7 @@
//config: memory in the system, as well as the buffers used by the kernel.
//config: The shared memory column should be ignored; it is obsolete.
//applet:IF_FREE(APPLET_NOEXEC(free, free, BB_DIR_USR_BIN, BB_SUID_DROP, free))
//applet:IF_FREE(APPLET_NOFORK(free, free, BB_DIR_USR_BIN, BB_SUID_DROP, free))
//kbuild:lib-$(CONFIG_FREE) += free.o
@ -40,25 +40,21 @@
struct globals {
unsigned mem_unit;
#if ENABLE_DESKTOP
unsigned unit_steps;
# define G_unit_steps G.unit_steps
uint8_t unit_steps;
# define G_unit_steps g->unit_steps
#else
# define G_unit_steps 10
#endif
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
setup_common_bufsiz(); \
/* NB: noexec applet - globals not zeroed */ \
} while (0)
};
/* Because of NOFORK, "globals" are not in global data */
static unsigned long long scale(unsigned long d)
static unsigned long long scale(struct globals *g, unsigned long d)
{
return ((unsigned long long)d * G.mem_unit) >> G_unit_steps;
return ((unsigned long long)d * g->mem_unit) >> G_unit_steps;
}
static unsigned long parse_cached_kb(void)
/* NOINLINE reduces main() stack usage, which makes code smaller (on x86 at least) */
static NOINLINE unsigned long parse_cached_kb(void)
{
char buf[60]; /* actual lines we expect are ~30 chars or less */
FILE *fp;
@ -69,7 +65,7 @@ static unsigned long parse_cached_kb(void)
if (sscanf(buf, "Cached: %lu %*s\n", &cached) == 1)
break;
}
if (ENABLE_FEATURE_CLEAN_UP)
/* Have to close because of NOFORK */
fclose(fp);
return cached;
@ -78,11 +74,10 @@ static unsigned long parse_cached_kb(void)
int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
{
struct globals G;
struct sysinfo info;
unsigned long long cached;
INIT_G();
#if ENABLE_DESKTOP
G.unit_steps = 10;
if (argv[1] && argv[1][0] == '-') {
@ -123,12 +118,12 @@ int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
#define FIELDS_2 (FIELDS_6 + 4*6)
printf(FIELDS_6,
scale(info.totalram), //total
scale(info.totalram - info.freeram), //used
scale(info.freeram), //free
scale(info.sharedram), //shared
scale(info.bufferram), //buffers
scale(cached) //cached
scale(&G, info.totalram), //total
scale(&G, info.totalram - info.freeram), //used
scale(&G, info.freeram), //free
scale(&G, info.sharedram), //shared
scale(&G, info.bufferram), //buffers
scale(&G, cached) //cached
);
/* Show alternate, more meaningful busy/free numbers by counting
* buffer cache as free memory. */
@ -136,15 +131,15 @@ int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
cached += info.freeram;
cached += info.bufferram;
printf(FIELDS_2,
scale(info.totalram - cached), //used
scale(cached) //free
scale(&G, info.totalram - cached), //used
scale(&G, cached) //free
);
#if BB_MMU
printf("Swap: ");
printf(FIELDS_3,
scale(info.totalswap), //total
scale(info.totalswap - info.freeswap), //used
scale(info.freeswap) //free
scale(&G, info.totalswap), //total
scale(&G, info.totalswap - info.freeswap), //used
scale(&G, info.freeswap) //free
);
#endif
return EXIT_SUCCESS;