shell: fix script's comm field if ENABLE_FEATURE_PREFER_APPLETS=y

function                                             old     new   delta
re_execed_comm                                         -      46     +46
main                                                  72      86     +14
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/0 up/down: 60/0)               Total: 60 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-11 18:39:25 +02:00
parent 23aba8a9a6
commit 5acf5e1f87
7 changed files with 78 additions and 2 deletions

View File

@ -1271,8 +1271,10 @@ void run_applet_no_and_exit(int a, const char *name, char **argv) NORETURN FAST_
#endif
void show_usage_if_dash_dash_help(int applet_no, char **argv) FAST_FUNC;
#if defined(__linux__)
int re_execed_comm(void) FAST_FUNC;
void set_task_comm(const char *comm) FAST_FUNC;
#else
# define re_execed_comm() 0
# define set_task_comm(name) ((void)0)
#endif

View File

@ -1112,9 +1112,15 @@ int main(int argc UNUSED_PARAM, char **argv)
|| ENABLE_FEATURE_PREFER_APPLETS
|| !BB_MMU
) {
if (NUM_APPLETS > 1)
if (NUM_APPLETS > 1) {
/* Careful, do not trash comm of "SCRIPT.sh" -
* the case when started from e.g. #!/bin/ash script.
* (not limited to shells - #!/bin/awk scripts also exist)
*/
if (re_execed_comm())
set_task_comm(applet_name);
}
}
parse_config_file(); /* ...maybe, if FEATURE_SUID_CONFIG */
run_applet_and_exit(applet_name, argv);

View File

@ -28,6 +28,22 @@
# ifndef PR_GET_NAME
# define PR_GET_NAME 16
# endif
# if ENABLE_FEATURE_SH_STANDALONE || ENABLE_FEATURE_PREFER_APPLETS || !BB_MMU
int FAST_FUNC re_execed_comm(void)
{
const char *e, *expected_comm;
char comm[16];
BUILD_BUG_ON(CONFIG_BUSYBOX_EXEC_PATH[0] != '/');
e = CONFIG_BUSYBOX_EXEC_PATH;
/* Hopefully (strrchr(e) - e) evaluates to constant at compile time: */
expected_comm = bb_busybox_exec_path + (strrchr(e, '/') - e) + 1;
prctl(PR_GET_NAME, (long)comm, 0, 0, 0);
//bb_error_msg("comm:'%.*s' expected:'%s'", 16, comm, expected_comm);
return strcmp(comm, expected_comm) == 0;
}
# endif
void FAST_FUNC set_task_comm(const char *comm)
{
/* okay if too long (truncates) */

View File

@ -0,0 +1,6 @@
./SCRIPT.sh:
/proc/N/comm: SCRIPT.sh
exec ./SCRIPT.sh:
/proc/N/comm: SCRIPT.sh
sh ./SCRIPT.sh:
/proc/N/comm: ash

View File

@ -0,0 +1,20 @@
{
echo "#!$THIS_SH"
echo 'procdir=/proc/$$'
#echo 'echo " /proc/N/exe: $(basename $(readlink $procdir/exe))"'
echo 'echo " /proc/N/comm: $(cat $procdir/comm)"'
} >SCRIPT.sh
chmod 755 SCRIPT.sh
# comm field was wrong if CONFIG_FEATURE_PREFER_APPLETS=y
echo './SCRIPT.sh:'
./SCRIPT.sh
# comm field was wrong if CONFIG_FEATURE_PREFER_APPLETS=y
echo 'exec ./SCRIPT.sh:'
(exec ./SCRIPT.sh)
echo 'sh ./SCRIPT.sh:'
$THIS_SH ./SCRIPT.sh
rm SCRIPT.sh

View File

@ -0,0 +1,6 @@
./SCRIPT.sh:
/proc/N/comm: SCRIPT.sh
exec ./SCRIPT.sh:
/proc/N/comm: SCRIPT.sh
sh ./SCRIPT.sh:
/proc/N/comm: hush

View File

@ -0,0 +1,20 @@
{
echo "#!$THIS_SH"
echo 'procdir=/proc/$$'
#echo 'echo " /proc/N/exe: $(basename $(readlink $procdir/exe))"'
echo 'echo " /proc/N/comm: $(cat $procdir/comm)"'
} >SCRIPT.sh
chmod 755 SCRIPT.sh
# comm field was wrong if CONFIG_FEATURE_PREFER_APPLETS=y
echo './SCRIPT.sh:'
./SCRIPT.sh
# comm field was wrong if CONFIG_FEATURE_PREFER_APPLETS=y
echo 'exec ./SCRIPT.sh:'
(exec ./SCRIPT.sh)
echo 'sh ./SCRIPT.sh:'
$THIS_SH ./SCRIPT.sh
rm SCRIPT.sh