Changeset 1765 in MondoRescue for branches/2.2.5/mindi-busybox/libbb/find_pid_by_name.c

Timestamp:

Nov 4, 2007, 3:16:40 AM (16 years ago)

Author:

Bruno Cornec

Message:

Update to busybox 1.7.2

File:

• branches/2.2.5/mindi-busybox/libbb/find_pid_by_name.c (modified) (2 diffs)

branches/2.2.5/mindi-busybox/libbb/find_pid_by_name.c

@@ -5 +5 @@
  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  *
- * Licensed under the GPL v2, see the file LICENSE in this tarball.
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 
-#include <stdio.h>
-#include <ctype.h>
-#include <string.h>
-#include <stdlib.h>
 #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()
@@ -24 +49 @@
  *  It is the caller's duty to free the returned pidlist.
  */
-long* find_pid_by_name( const char* pidName)
+pid_t* find_pid_by_name(const char* procName)
 {
-    long* pidList;
-    int i=0;
-    procps_status_t * p;
+    pid_t* pidList;
+    int i = 0;
+    procps_status_t* p = NULL;
 
-    pidList = xmalloc(sizeof(long));
-    while ((p = procps_scan(0)) != 0)
-    {
-        if (strncmp(p->short_cmd, pidName, COMM_LEN-1) == 0) {
-            pidList=xrealloc( pidList, sizeof(long) * (i+2));
-            pidList[i++]=p->pid;
+    pidList = xmalloc(sizeof(*pidList));
+    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 exe, do we want that? */
+        ) {
+            pidList = xrealloc(pidList, sizeof(*pidList) * (i+2));
+            pidList[i++] = p->pid;
         }
     }
 
-    pidList[i] = i==0 ? -1 : 0;
+    pidList[i] = 0;
     return pidList;
 }
 
-long *pidlist_reverse(long *pidList)
+pid_t *pidlist_reverse(pid_t *pidList)
 {
-    int i=0;
-    while (pidList[i] > 0 && ++i);
-    if ( i-- > 0) {
-        long k;
+    int i = 0;
+    while (pidList[i])
+        i++;
+    if (--i >= 0) {
+        pid_t k;
         int j;
         for (j = 0; i > j; i--, j++) {