From d2e07bc16cbd68bc2771f9f163e610e4e327c67c Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Fri, 16 Aug 2013 11:48:48 +0200 Subject: [PATCH] init: don't use fixed size buffer for command We store init actions forever. 256 bytes per action means that a typical inittab of ~10 commands uses 2.5k just to remember command strings - which are usually _much_ shorter than 256 bytes. At a cost of a bit more code, it's possible to allocate only actually needed amount. function old new delta init_exec 224 248 +24 new_init_action 140 142 +2 Signed-off-by: Denys Vlasenko --- init/init.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/init/init.c b/init/init.c index f3a35d532..05ed4f7a7 100644 --- a/init/init.c +++ b/init/init.c @@ -140,7 +140,6 @@ * not fully functional init by switching it on! */ #define DEBUG_INIT 0 -#define COMMAND_SIZE 256 #define CONSOLE_NAME_SIZE 32 /* Default sysinit script. */ @@ -195,7 +194,7 @@ struct init_action { pid_t pid; uint8_t action_type; char terminal[CONSOLE_NAME_SIZE]; - char command[COMMAND_SIZE]; + char command[1]; }; static struct init_action *init_action_list = NULL; @@ -398,7 +397,7 @@ static void reset_sighandlers_and_unblock_sigs(void) } /* Wrapper around exec: - * Takes string (max COMMAND_SIZE chars). + * Takes string. * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'. * Otherwise splits words on whitespace, deals with leading dash, * and uses plain exec(). @@ -406,10 +405,15 @@ static void reset_sighandlers_and_unblock_sigs(void) */ static void init_exec(const char *command) { - char *cmd[COMMAND_SIZE / 2]; - char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */ - int dash = (command[0] == '-' /* maybe? && command[1] == '/' */); + /* +8 allows to write VLA sizes below more efficiently: */ + unsigned command_size = strlen(command) + 8; + /* strlen(command) + strlen("exec ")+1: */ + char buf[command_size]; + /* strlen(command) / 2 + 4: */ + char *cmd[command_size / 2]; + int dash; + dash = (command[0] == '-' /* maybe? && command[1] == '/' */); command += dash; /* See if any special /bin/sh requiring characters are present */ @@ -626,13 +630,13 @@ static void new_init_action(uint8_t action_type, const char *command, const char nextp = &a->next; } - a = xzalloc(sizeof(*a)); + a = xzalloc(sizeof(*a) + strlen(command)); /* Append to the end of the list */ append: *nextp = a; a->action_type = action_type; - safe_strncpy(a->command, command, sizeof(a->command)); + strcpy(a->command, command); safe_strncpy(a->terminal, cons, sizeof(a->terminal)); dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n", a->command, a->action_type, a->terminal);