Hi to all,
this patch started as a personal fun and learning project on swapon/swapoff
after
Matt Whitlock's patches. I was curios if there was a way to remove all the
#ifdefs
from within the code as for my personal taste this unindented stuff in indented
code makes the code harder to read.
So I tried hard by using the preprocessor and compilers dead code elimination
and in the end I was able to achieve my goal: a ifdef free code.
During the process as side effects I spotted a few differences between
our swapon/swapoff inplementation and the one on my debian box
so I added this fixes/improvements to the code:
1) real swapon/swapoff handles also devices on the commandline with -a;
2) xstat(device) in swap_enable_disable aborts on error when cycling through
fstab so some devices are not handled;
3) duplicated code for ENABLE_FEATURE_SWAPON_DISCARD and
ENABLE_FEATURE_SWAPON_PRI was moved to functions.
4) silence some error messages with -a;
5) minor cleanups and code refactoring reduced the size as per bloat-check:
./scripts/bloat-o-meter busybox_unstripped.old busybox_unstripped
function old new delta
set_discard_flag - 106 +106
set_priority_flag - 75 +75
swap_enable_disable 149 219 +70
.rodata 141270 141260 -10
swap_on_off_main 638 325 -313
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 1/2 up/down: 251/-323) Total: -72 bytes
6) I also added support for /proc/swaps handling to swapoff:
"When the -a flag is given, swapping is disabled on all known swap devices
and files (as found in /proc/swaps or /etc/fstab)."
So now swapoff first cycles through /proc/swaps and then through fstab
to swapoff all devices.
With this additional feature bloat-check is:
./scripts/bloat-o-meter busybox_unstripped.old busybox_unstripped
function old new delta
set_discard_flag - 106 +106
set_priority_flag - 75 +75
swap_enable_disable 149 219 +70
.rodata 141270 141272 +2
swap_on_off_main 638 416 -222
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 2/1 up/down: 253/-222) Total: 31 bytes
so it comes at almost no extra size cost.
I've decided not to add an extra config option for that, but it could
be easily added if needed.
7) Something I'm forgettin...;
Sadly I cannot provide a patch series for the different changes but
only a allinone patch, therefore I also attach a drop-in replacement
file for swaponoff.c for review and testing by the list members.
I've tested it a little on my box with a few test cases I could think of,
but more testing is needed as there is a lot of code changed and bugs
can creep in.
Hint, critics and improvements are welcome.
Ciao,
Tito
Swapon/swapoff fixes, enhacements and size reduction:
1) real swapon/swapoff handles also devices on the commandline with -a;
2) xstat(device) in swap_enable_disable aborts on error when cycling through
fstab so some devices are not handled;
3) duplicated code for ENABLE_FEATURE_SWAPON_DISCARD and
ENABLE_FEATURE_SWAPON_PRI was moved to functions.
4) silence some error messages with -a;
5) minor cleanups and code refactoring to reduce binary size.
6) added support for /proc/swaps handling to swapoff.
Signed-off by Tito Ragusa <[email protected]>
--- util-linux/swaponoff.c.orig 2014-03-26 07:46:29.263718690 +0100
+++ util-linux/swaponoff.c 2014-03-30 21:49:11.642492640 +0200
@@ -63,90 +63,142 @@
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define g_flags (G.flags)
+#define save_g_flags() int save_g_flags = g_flags
+#define restore_g_flags() g_flags = save_g_flags
#else
#define g_flags 0
+#define save_g_flags() ((void)0)
+#define restore_g_flags() ((void)0)
#endif
#define INIT_G() do { } while (0)
+#define do_swapoff (applet_name[5] == 'f')
+
+/* Command line options */
+enum {
+ OPTBIT_a, /* -a all */
+ IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard */
+ IF_FEATURE_SWAPON_PRI ( OPTBIT_p ,) /* -p priority */
+ OPT_a = 1 << OPTBIT_a,
+ OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
+ OPT_p = IF_FEATURE_SWAPON_PRI ((1 << OPTBIT_p)) + 0,
+};
+
+#define OPT_ALL (option_mask32 & OPT_a)
+#define OPT_DISCARD (option_mask32 & OPT_d)
+#define OPT_PRIO (option_mask32 & OPT_p)
+
static int swap_enable_disable(char *device)
{
- int status;
+ int err = 0;
+ int quiet = 0;
struct stat st;
resolve_mount_spec(&device);
- xstat(device, &st);
-
-#if ENABLE_DESKTOP
- /* test for holes */
- if (S_ISREG(st.st_mode))
- if (st.st_blocks * (off_t)512 < st.st_size)
- bb_error_msg("warning: swap file has holes");
-#endif
-
- if (applet_name[5] == 'n')
- status = swapon(device, g_flags);
- else
- status = swapoff(device);
+
+ if (do_swapoff) {
+ err = swapoff(device);
+ /* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
+ quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
+ } else {
+ /* swapon */
+ err = stat(device, &st);
+ if (!err) {
+ if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
+ if (st.st_blocks * (off_t)512 < st.st_size) {
+ bb_error_msg("%s: file has holes", device);
+ return 1;
+ }
+ }
+ err = swapon(device, g_flags);
+ /* Don't complain on swapon -a if device is already in use */
+ quiet = (OPT_ALL && errno == EBUSY);
+ }
+ }
- if (status != 0) {
- bb_simple_perror_msg(device);
+ if (err) {
+ if (!quiet)
+ bb_simple_perror_msg(device);
return 1;
}
-
return 0;
}
-static int do_em_all(void)
+#if ENABLE_FEATURE_SWAPON_DISCARD
+static void set_discard_flag(char *s)
{
- struct mntent *m;
- FILE *f;
- int err;
-#ifdef G
- int cl_flags = g_flags;
+ /* Unset the flag first to allow fstab options to override */
+ /* options set on the command line */
+ g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
+
+ if (!s) /* No optional policy value on the commandline */
+ return;
+ /* Skip prepended '=' */
+ if (*s == '=')
+ s += 1;
+ /* For fstab parsing: remove other appended options */
+ *strchrnul(s, ',') = '\0';
+
+ if (strcmp(s, "once") == 0)
+ g_flags |= SWAP_FLAG_DISCARD_ONCE;
+ if (strcmp(s, "pages") == 0)
+ g_flags |= SWAP_FLAG_DISCARD_PAGES;
+}
+#else
+#define set_discard_flag(s) ((void)0)
#endif
- f = setmntent("/etc/fstab", "r");
- if (f == NULL)
- bb_perror_msg_and_die("/etc/fstab");
+#if ENABLE_FEATURE_SWAPON_PRI
+static void set_priority_flag(char *s)
+{
+ unsigned prio;
+
+ /* For fstab parsing: remove other appended options */
+ *strchrnul(s, ',') = '\0';
+ /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
+ prio = bb_strtou(s, NULL, 10);
+ if (!errno) {
+ /* Unset the flag first to allow fstab options to override */
+ /* options set on the command line */
+ g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
+ MIN(prio, SWAP_FLAG_PRIO_MASK);
+ }
+}
+#else
+#define set_priority_flag(s) ((void)0)
+#endif
- err = 0;
+static int do_em_all_in_fstab(void)
+{
+ struct mntent *m;
+ int err = 0;
+ FILE *f = xfopen_for_read("/etc/fstab");
+
while ((m = getmntent(f)) != NULL) {
if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
/* swapon -a should ignore entries with noauto,
- * but swapoff -a should process them */
- if (applet_name[5] != 'n'
- || hasmntopt(m, MNTOPT_NOAUTO) == NULL
- ) {
-#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
- char *p;
- g_flags = cl_flags; /* each swap space might have different flags */
-#if ENABLE_FEATURE_SWAPON_DISCARD
- p = hasmntopt(m, "discard");
- if (p) {
- if (p[7] == '=') {
- if (strncmp(p + 8, "once", 4) == 0 && (p[12] == ',' || p[12] == '\0'))
- g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE;
- else if (strncmp(p + 8, "pages", 5) == 0 && (p[13] == ',' || p[13] == '\0'))
- g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_PAGES;
+ * but swapoff -a should process them */
+ if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
+ char *p __attribute__((unused)); /* maybe unused*/
+ /* each swap space might have different flags */
+ /* save global flags for the next round */
+ save_g_flags();
+ if (ENABLE_FEATURE_SWAPON_DISCARD) {
+ p = hasmntopt(m, "discard");
+ if (p) {
+ /* move to '=' or to end of string */
+ p += 7;
+ set_discard_flag(p);
}
- else if (p[7] == ',' || p[7] == '\0')
- g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
}
-#endif
-#if ENABLE_FEATURE_SWAPON_PRI
- p = hasmntopt(m, "pri");
- if (p) {
- /* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
- unsigned prio = bb_strtou(p + 4, NULL, 10);
- /* We want to allow "NNNN,foo", thus errno == EINVAL is allowed too */
- if (errno != ERANGE) {
- g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
- MIN(prio, SWAP_FLAG_PRIO_MASK);
+ if (ENABLE_FEATURE_SWAPON_PRI) {
+ p = hasmntopt(m, "pri");
+ if (p) {
+ set_priority_flag(p + 4);
}
}
-#endif
-#endif
- err += swap_enable_disable(m->mnt_fsname);
+ err |= swap_enable_disable(m->mnt_fsname);
+ restore_g_flags();
}
}
}
@@ -157,74 +209,67 @@
return err;
}
+static int do_all_in_proc_swaps(void)
+{
+ char *line;
+ int err = 0;
+ FILE *f = fopen_for_read("/proc/swaps");
+ /* Don't complain if missing */
+ if (f) {
+ while ((line = xmalloc_fgetline(f))){
+ if (line[0] == '/') {
+ *strchrnul(line, ' ') = '\0';
+ err |= swap_enable_disable(line);
+ }
+ free(line);
+ }
+ if (ENABLE_FEATURE_CLEAN_UP)
+ fclose(f);
+ }
+
+ return err;
+}
+
+#define OPTSTR_SWAPON "a" \
+ IF_FEATURE_SWAPON_DISCARD("d::") \
+ IF_FEATURE_SWAPON_PRI("p:")
+
int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
{
- int ret;
-#if ENABLE_FEATURE_SWAPON_DISCARD
- char *discard = NULL;
-#endif
-#if ENABLE_FEATURE_SWAPON_PRI
- unsigned prio;
-#endif
+ char *prio __attribute__((unused)); /* maybe unused*/
+ char *discard __attribute__((unused)) = NULL; /* maybe unused*/
+ int ret = 0;
INIT_G();
-#if !ENABLE_FEATURE_SWAPON_DISCARD && !ENABLE_FEATURE_SWAPON_PRI
- ret = getopt32(argv, "a");
-#else
-#if ENABLE_FEATURE_SWAPON_PRI
- if (applet_name[5] == 'n')
- opt_complementary = "p+";
-#endif
- ret = getopt32(argv, (applet_name[5] == 'n') ?
-#if ENABLE_FEATURE_SWAPON_DISCARD
- "d::"
-#endif
-#if ENABLE_FEATURE_SWAPON_PRI
- "p:"
-#endif
- "a" : "a"
-#if ENABLE_FEATURE_SWAPON_DISCARD
- , &discard
-#endif
-#if ENABLE_FEATURE_SWAPON_PRI
- , &prio
-#endif
- );
-#endif
-
-#if ENABLE_FEATURE_SWAPON_DISCARD
- if (ret & 1) { // -d
- if (!discard)
- g_flags |= SWAP_FLAG_DISCARD;
- else if (strcmp(discard, "once") == 0)
- g_flags |= SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE;
- else if (strcmp(discard, "pages") == 0)
- g_flags |= SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_PAGES;
- else
- bb_show_usage();
- }
- ret >>= 1;
-#endif
-#if ENABLE_FEATURE_SWAPON_PRI
- if (ret & 1) // -p
- g_flags |= SWAP_FLAG_PREFER |
- MIN(prio, SWAP_FLAG_PRIO_MASK);
- ret >>= 1;
-#endif
-
- if (ret /* & 1: not needed */) // -a
- return do_em_all();
+ getopt32(argv, (do_swapoff) ? "a" : OPTSTR_SWAPON
+ IF_FEATURE_SWAPON_DISCARD(,&discard)
+ IF_FEATURE_SWAPON_PRI(, &prio));
argv += optind;
- if (!*argv)
- bb_show_usage();
- /* ret = 0; redundant */
- do {
- ret += swap_enable_disable(*argv);
- } while (*++argv);
+ if (OPT_DISCARD) {
+ set_discard_flag(discard);
+ }
+ if (OPT_PRIO) {
+ set_priority_flag(prio);
+ }
+ if (OPT_ALL) {
+ /* swapoff -a does also /proc/swaps */
+ if (do_swapoff)
+ ret = do_all_in_proc_swaps();
+ ret |= do_em_all_in_fstab();
+ } else if (!*argv) {
+ /* if not -a we need at least one arg */
+ bb_show_usage();
+ }
+ /* Unset -a now to allow for more error more messages in swap_enable_disable */
+ option_mask32 = option_mask32 & ~OPT_a;
+ /* Now process devices on the commandline if any */
+ while (*argv) {
+ ret |= swap_enable_disable(*argv++);
+ }
return ret;
}
/* vi: set sw=4 ts=4: */
/*
* Mini swapon/swapoff implementation for busybox
*
* Copyright (C) 1999-2004 by Erik Andersen <[email protected]>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//usage:#define swapon_trivial_usage
//usage: "[-a]" IF_FEATURE_SWAPON_DISCARD(" [-d[POL]]") IF_FEATURE_SWAPON_PRI(" [-p PRI]") " [DEVICE]"
//usage:#define swapon_full_usage "\n\n"
//usage: "Start swapping on DEVICE\n"
//usage: "\n -a Start swapping on all swap devices"
//usage: IF_FEATURE_SWAPON_DISCARD(
//usage: "\n -d[POL] Discard blocks at swapon (POL=once),"
//usage: "\n as freed (POL=pages), or both (POL omitted)"
//usage: )
//usage: IF_FEATURE_SWAPON_PRI(
//usage: "\n -p PRI Set swap device priority"
//usage: )
//usage:
//usage:#define swapoff_trivial_usage
//usage: "[-a] [DEVICE]"
//usage:#define swapoff_full_usage "\n\n"
//usage: "Stop swapping on DEVICE\n"
//usage: "\n -a Stop swapping on all swap devices"
#include "libbb.h"
#include <mntent.h>
#ifndef __BIONIC__
# include <sys/swap.h>
#endif
#if ENABLE_FEATURE_MOUNT_LABEL
# include "volume_id.h"
#else
# define resolve_mount_spec(fsname) ((void)0)
#endif
#ifndef MNTTYPE_SWAP
# define MNTTYPE_SWAP "swap"
#endif
#if ENABLE_FEATURE_SWAPON_DISCARD
#ifndef SWAP_FLAG_DISCARD
#define SWAP_FLAG_DISCARD 0x10000
#endif
#ifndef SWAP_FLAG_DISCARD_ONCE
#define SWAP_FLAG_DISCARD_ONCE 0x20000
#endif
#ifndef SWAP_FLAG_DISCARD_PAGES
#define SWAP_FLAG_DISCARD_PAGES 0x40000
#endif
#define SWAP_FLAG_DISCARD_MASK \
(SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | SWAP_FLAG_DISCARD_PAGES)
#endif
#if ENABLE_FEATURE_SWAPON_DISCARD || ENABLE_FEATURE_SWAPON_PRI
struct globals {
int flags;
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define g_flags (G.flags)
#define save_g_flags() int save_g_flags = g_flags
#define restore_g_flags() g_flags = save_g_flags
#else
#define g_flags 0
#define save_g_flags() ((void)0)
#define restore_g_flags() ((void)0)
#endif
#define INIT_G() do { } while (0)
#define do_swapoff (applet_name[5] == 'f')
/* Command line options */
enum {
OPTBIT_a, /* -a all */
IF_FEATURE_SWAPON_DISCARD( OPTBIT_d ,) /* -d discard */
IF_FEATURE_SWAPON_PRI ( OPTBIT_p ,) /* -p priority */
OPT_a = 1 << OPTBIT_a,
OPT_d = IF_FEATURE_SWAPON_DISCARD((1 << OPTBIT_d)) + 0,
OPT_p = IF_FEATURE_SWAPON_PRI ((1 << OPTBIT_p)) + 0,
};
#define OPT_ALL (option_mask32 & OPT_a)
#define OPT_DISCARD (option_mask32 & OPT_d)
#define OPT_PRIO (option_mask32 & OPT_p)
static int swap_enable_disable(char *device)
{
int err = 0;
int quiet = 0;
struct stat st;
resolve_mount_spec(&device);
if (do_swapoff) {
err = swapoff(device);
/* Don't complain on OPT_ALL if not a swap device or if it doesn't exist */
quiet = (OPT_ALL && (errno == EINVAL || errno == ENOENT));
} else {
/* swapon */
err = stat(device, &st);
if (!err) {
if (ENABLE_DESKTOP && S_ISREG(st.st_mode)) {
if (st.st_blocks * (off_t)512 < st.st_size) {
bb_error_msg("%s: file has holes", device);
return 1;
}
}
err = swapon(device, g_flags);
/* Don't complain on swapon -a if device is already in use */
quiet = (OPT_ALL && errno == EBUSY);
}
}
if (err) {
if (!quiet)
bb_simple_perror_msg(device);
return 1;
}
return 0;
}
#if ENABLE_FEATURE_SWAPON_DISCARD
static void set_discard_flag(char *s)
{
/* Unset the flag first to allow fstab options to override */
/* options set on the command line */
g_flags = (g_flags & ~SWAP_FLAG_DISCARD_MASK) | SWAP_FLAG_DISCARD;
if (!s) /* No optional policy value on the commandline */
return;
/* Skip prepended '=' */
if (*s == '=')
s += 1;
/* For fstab parsing: remove other appended options */
*strchrnul(s, ',') = '\0';
if (strcmp(s, "once") == 0)
g_flags |= SWAP_FLAG_DISCARD_ONCE;
if (strcmp(s, "pages") == 0)
g_flags |= SWAP_FLAG_DISCARD_PAGES;
}
#else
#define set_discard_flag(s) ((void)0)
#endif
#if ENABLE_FEATURE_SWAPON_PRI
static void set_priority_flag(char *s)
{
unsigned prio;
/* For fstab parsing: remove other appended options */
*strchrnul(s, ',') = '\0';
/* Max allowed 32767 (== SWAP_FLAG_PRIO_MASK) */
prio = bb_strtou(s, NULL, 10);
if (!errno) {
/* Unset the flag first to allow fstab options to override */
/* options set on the command line */
g_flags = (g_flags & ~SWAP_FLAG_PRIO_MASK) | SWAP_FLAG_PREFER |
MIN(prio, SWAP_FLAG_PRIO_MASK);
}
}
#else
#define set_priority_flag(s) ((void)0)
#endif
static int do_em_all_in_fstab(void)
{
struct mntent *m;
int err = 0;
FILE *f = xfopen_for_read("/etc/fstab");
while ((m = getmntent(f)) != NULL) {
if (strcmp(m->mnt_type, MNTTYPE_SWAP) == 0) {
/* swapon -a should ignore entries with noauto,
* but swapoff -a should process them */
if (do_swapoff || hasmntopt(m, MNTOPT_NOAUTO) == NULL) {
char *p __attribute__((unused)); /* maybe unused*/
/* each swap space might have different flags */
/* save global flags for the next round */
save_g_flags();
if (ENABLE_FEATURE_SWAPON_DISCARD) {
p = hasmntopt(m, "discard");
if (p) {
/* move to '=' or to end of string */
p += 7;
set_discard_flag(p);
}
}
if (ENABLE_FEATURE_SWAPON_PRI) {
p = hasmntopt(m, "pri");
if (p) {
set_priority_flag(p + 4);
}
}
err |= swap_enable_disable(m->mnt_fsname);
restore_g_flags();
}
}
}
if (ENABLE_FEATURE_CLEAN_UP)
endmntent(f);
return err;
}
static int do_all_in_proc_swaps(void)
{
char *line;
int err = 0;
FILE *f = fopen_for_read("/proc/swaps");
/* Don't complain if missing */
if (f) {
while ((line = xmalloc_fgetline(f))){
if (line[0] == '/') {
*strchrnul(line, ' ') = '\0';
err |= swap_enable_disable(line);
}
free(line);
}
if (ENABLE_FEATURE_CLEAN_UP)
fclose(f);
}
return err;
}
#define OPTSTR_SWAPON "a" \
IF_FEATURE_SWAPON_DISCARD("d::") \
IF_FEATURE_SWAPON_PRI("p:")
int swap_on_off_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int swap_on_off_main(int argc UNUSED_PARAM, char **argv)
{
char *prio __attribute__((unused)); /* maybe unused*/
char *discard __attribute__((unused)) = NULL; /* maybe unused*/
int ret = 0;
INIT_G();
getopt32(argv, (do_swapoff) ? "a" : OPTSTR_SWAPON
IF_FEATURE_SWAPON_DISCARD(,&discard)
IF_FEATURE_SWAPON_PRI(, &prio));
argv += optind;
if (OPT_DISCARD) {
set_discard_flag(discard);
}
if (OPT_PRIO) {
set_priority_flag(prio);
}
if (OPT_ALL) {
/* swapoff -a does also /proc/swaps */
if (do_swapoff)
ret = do_all_in_proc_swaps();
ret |= do_em_all_in_fstab();
} else if (!*argv) {
/* if not -a we need at least one arg */
bb_show_usage();
}
/* Unset -a now to allow for more error more messages in swap_enable_disable */
option_mask32 = option_mask32 & ~OPT_a;
/* Now process devices on the commandline if any */
while (*argv) {
ret |= swap_enable_disable(*argv++);
}
return ret;
}
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