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init: don't use fixed size buffer for command

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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 <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2013-08-16 11:48:48 +02:00
parent 73fbe9dc86
commit d2e07bc16c
1 changed files with 12 additions and 8 deletions
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20
init/init.c
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@ -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);