aboutsummaryrefslogtreecommitdiff
path: root/include/busybox.h
diff options
context:
space:
mode:
authorGravatar Ron Yorston <rmy@pobox.com>2016-03-30 00:42:05 +0200
committerGravatar Denys Vlasenko <vda.linux@googlemail.com>2016-03-30 00:44:11 +0200
commit610c4c385b38280c7bde7a48d95ec019cbfe1ab4 (patch)
tree82ad4366ce9e927f64efa89d178c4dd2bfea1435 /include/busybox.h
parent9844d7e830a2c55421e27e8828d2067c50f57c23 (diff)
downloadbusybox-610c4c385b38280c7bde7a48d95ec019cbfe1ab4.tar.gz
busybox-610c4c385b38280c7bde7a48d95ec019cbfe1ab4.tar.bz2
applet_tables: save space by removing applet name offsets
The array applet_nameofs consumes two bytes per applet. It encodes nofork/noexec flags suid flags the offset of the applet name in the applet_name string Change the applet_table build tool to store the flags in two separate arrays (applet_flags and applet_suid). Replace applet_nameofs[] with a smaller version that only stores a limited number of offsets. This requires changes to the macros APPLET_IS_NOFORK, APPLET_IS_NOEXEC and APPLET_SUID. According to Valgrind the original find_applet_by_name required 353 cycles per call, averaged over all names. Adjusting the number of known offsets allows space to be traded off against execution time: KNOWN_OFFSETS cycles bytes (wrt KNOWN_OFFSETS = 0) 0 9057 - 2 4604 32 4 2407 75 8 1342 98 16 908 130 32 884 194 This patch uses KNOWN_OFFSETS = 8. v2: Remove some dead code from the applet_table tool; Treat the applet in the middle of the table as a special case. v3: Use the middle applet to adjust the start of the linear search as well as the last applet found. v4: Use an augmented linear search in find_applet_by_name. Drop the special treatment of the middle name from get_applet_name: most of the advantage now derives from the last stored value. v5: Don't store index in applet_nameofs, it can be calculated. v6: Tweaks by Denys function old new delta find_applet_by_name 25 125 +100 applet_suid - 92 +92 run_applet_no_and_exit 452 460 +8 run_applet_and_exit 695 697 +2 applet_name_compare 31 - -31 applet_nameofs 734 14 -720 ------------------------------------------------------------------------------ (add/remove: 1/1 grow/shrink: 3/1 up/down: 202/-751) Total: -549 bytes text data bss dec hex filename 925464 906 17160 943530 e65aa busybox_old 924915 906 17160 942981 e6385 busybox_unstripped Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'include/busybox.h')
-rw-r--r--include/busybox.h15
1 files changed, 5 insertions, 10 deletions
diff --git a/include/busybox.h b/include/busybox.h
index b1e31e5ee..737627bd0 100644
--- a/include/busybox.h
+++ b/include/busybox.h
@@ -15,25 +15,20 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
/* Keep in sync with applets/applet_tables.c! */
extern const char applet_names[] ALIGN1;
extern int (*const applet_main[])(int argc, char **argv);
-extern const uint16_t applet_nameofs[];
+extern const uint8_t applet_flags[] ALIGN1;
+extern const uint8_t applet_suid[] ALIGN1;
extern const uint8_t applet_install_loc[] ALIGN1;
-#if ENABLE_FEATURE_SUID || ENABLE_FEATURE_PREFER_APPLETS
-# define APPLET_NAME(i) (applet_names + (applet_nameofs[i] & 0x0fff))
-#else
-# define APPLET_NAME(i) (applet_names + applet_nameofs[i])
-#endif
-
#if ENABLE_FEATURE_PREFER_APPLETS
-# define APPLET_IS_NOFORK(i) (applet_nameofs[i] & (1 << 12))
-# define APPLET_IS_NOEXEC(i) (applet_nameofs[i] & (1 << 13))
+# define APPLET_IS_NOFORK(i) (applet_flags[(i)/4] & (1 << (2 * ((i)%4))))
+# define APPLET_IS_NOEXEC(i) (applet_flags[(i)/4] & (1 << ((2 * ((i)%4))+1)))
#else
# define APPLET_IS_NOFORK(i) 0
# define APPLET_IS_NOEXEC(i) 0
#endif
#if ENABLE_FEATURE_SUID
-# define APPLET_SUID(i) ((applet_nameofs[i] >> 14) & 0x3)
+# define APPLET_SUID(i) ((applet_suid[(i)/4] >> (2 * ((i)%4)) & 3))
#endif
#if ENABLE_FEATURE_INSTALLER