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pidof: size optimizations (-50 bytes)

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This commit is contained in:
Denis Vlasenko 2007-06-23 14:56:43 +00:00
parent 118b81df76
commit 198badafd8
3 changed files with 44 additions and 20 deletions
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2
include/usage.h
View File

@ -2544,7 +2544,7 @@
USE_FEATURE_PIDOF_SINGLE( \
"\n -s Display only a single PID") \
USE_FEATURE_PIDOF_OMIT( \
"\n -o Omit given pid") \
"\n -o PID Omit given pid") \
USE_FEATURE_PIDOF_OMIT( \
"\n Use %PPID to omit the parent pid of pidof itself")
#define pidof_example_usage \

29
libbb/find_pid_by_name.c
View File

@ -9,6 +9,35 @@
#include "libbb.h"
/*
In Linux we have three ways to determine "process name":
1. /proc/PID/stat has "...(name)...", among other things. It's so-called "comm" field.
2. /proc/PID/cmdline's first NUL-terminated string. It's argv[0] from exec syscall.
3. /proc/PID/exe symlink. Points to the running executable file.
kernel threads:
comm: thread name
cmdline: empty
exe: <readlink fails>
executable
comm: first 15 chars of base name
(if executable is a symlink, then first 15 chars of symlink name are used)
cmdline: argv[0] from exec syscall
exe: points to executable (resolves symlink, unlike comm)
script (an executable with #!/path/to/interpreter):
comm: first 15 chars of script's base name (symlinks are not resolved)
cmdline: /path/to/interpreter (symlinks are not resolved)
(script name is in argv[1], args are pushed into argv[2] etc)
exe: points to interpreter's executable (symlinks are resolved)
If FEATURE_PREFER_APPLETS=y (and more so if FEATURE_SH_STANDALONE=y),
some commands started from busybox shell, xargs or find are started by
execXXX("/proc/self/exe", applet_name, params....)
and therefore comm field contains "exe".
*/
/* find_pid_by_name()
*
* Modified by Vladimir Oleynik for use with libbb/procps.c

33
procps/pidof.c
View File

@ -20,9 +20,9 @@ int pidof_main(int argc, char **argv);
int pidof_main(int argc, char **argv)
{
unsigned first = 1;
unsigned fail = 1;
unsigned opt;
#if ENABLE_FEATURE_PIDOF_OMIT
char ppid_str[sizeof(int)*3 + 1];
llist_t *omits = NULL; /* list of pids to omit */
opt_complementary = "o::";
#endif
@ -35,14 +35,12 @@ int pidof_main(int argc, char **argv)
#if ENABLE_FEATURE_PIDOF_OMIT
/* fill omit list. */
{
char getppid_str[sizeof(int)*3 + 1];
llist_t * omits_p = omits;
llist_t *omits_p = omits;
while (omits_p) {
/* are we asked to exclude the parent's process ID? */
if (!strncmp(omits_p->data, "%PPID", 5)) {
llist_pop(&omits_p);
snprintf(getppid_str, sizeof(getppid_str), "%u", (unsigned)getppid());
llist_add_to(&omits_p, getppid_str);
if (strcmp(omits_p->data, "%PPID") == 0) {
sprintf(ppid_str, "%u", (unsigned)getppid());
omits_p->data = ppid_str;
}
omits_p = omits_p->link;
}
@ -56,27 +54,24 @@ int pidof_main(int argc, char **argv)
/* reverse the pidlist like GNU pidof does. */
pidList = pidlist_reverse(find_pid_by_name(argv[optind]));
for (pl = pidList; *pl; pl++) {
SKIP_FEATURE_PIDOF_OMIT(const) unsigned omitted = 0;
#if ENABLE_FEATURE_PIDOF_OMIT
if (opt & OPT_OMIT) {
llist_t *omits_p = omits;
while (omits_p) {
if (xatoul(omits_p->data) == *pl) {
omitted = 1;
break;
} else
omits_p = omits_p->link;
goto omitting;
}
omits_p = omits_p->link;
}
}
#endif
if (!omitted) {
printf(" %u" + first, (unsigned)*pl);
first = 0;
}
fail = (!ENABLE_FEATURE_PIDOF_OMIT && omitted);
printf(" %u" + first, (unsigned)*pl);
first = 0;
if (ENABLE_FEATURE_PIDOF_SINGLE && (opt & OPT_SINGLE))
break;
#if ENABLE_FEATURE_PIDOF_OMIT
omitting: ;
#endif
}
free(pidList);
optind++;
@ -87,5 +82,5 @@ int pidof_main(int argc, char **argv)
if (ENABLE_FEATURE_CLEAN_UP)
llist_free(omits, NULL);
#endif
return fail ? EXIT_FAILURE : EXIT_SUCCESS;
return first; /* 1 (failure) - no processes found */
}