*: introduce and use FAST_FUNC: regparm on i386, otherwise no-on

[oweals/busybox.git] / libbb / find_pid_by_name.c

diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
index 05f7f968f872cfb443166ea9a03bd7d8e3f49123..ae2f11643cb61a22bb86a7aaf1609f443348a92d 100644 (file)
--- a/libbb/find_pid_by_name.c
+++ b/libbb/find_pid_by_name.c
@@ -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
@@ -19,15 +48,23 @@
  *  Returns a list of all matching PIDs
  *  It is the caller's duty to free the returned pidlist.
  */
-pid_t* find_pid_by_name(const char* procName)
+pid_t* FAST_FUNC find_pid_by_name(const char* procName)
 {
        pid_t* pidList;
        int i = 0;
-       procps_status_t* p;
+       procps_status_t* p = NULL;
 
        pidList = xmalloc(sizeof(*pidList));
-       while ((p = procps_scan(0)) != 0) {
-               if (strncmp(p->short_cmd, procName, COMM_LEN-1) == 0) {
+       while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGV0))) {
+               if (
+               /* we require comm to match and to not be truncated */
+               /* in Linux, if comm is 15 chars, it may be a truncated
+                * name, so we don't allow that to match */
+                   (!p->comm[sizeof(p->comm)-2] && strcmp(p->comm, procName) == 0)
+               /* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
+                || (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
+               /* TOOD: we can also try /proc/NUM/exe link, do we want that? */
+               ) {
                        pidList = xrealloc(pidList, sizeof(*pidList) * (i+2));
                        pidList[i++] = p->pid;
                }
@@ -37,7 +74,7 @@ pid_t* find_pid_by_name(const char* procName)
        return pidList;
 }
 
-pid_t *pidlist_reverse(pid_t *pidList)
+pid_t* FAST_FUNC pidlist_reverse(pid_t *pidList)
 {
        int i = 0;
        while (pidList[i])