1 files changed, 117 insertions, 0 deletions
diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
new file mode 100644
index 0000000..92d6d02
--- /dev/null
+++ b/libbb/find_pid_by_name.c
@@ -0,0 +1,117 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
+ *
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ */
+
+#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".
+*/
+
+static int comm_match(procps_status_t *p, const char *procName)
+{
+	int argv1idx;
+
+	/* comm does not match */
+	if (strncmp(p->comm, procName, 15) != 0)
+		return 0;
+
+	/* in Linux, if comm is 15 chars, it may be a truncated */
+	if (p->comm[14] == '\0') /* comm is not truncated - match */
+		return 1;
+
+	/* comm is truncated, but first 15 chars match.
+	 * This can be crazily_long_script_name.sh!
+	 * The telltale sign is basename(argv[1]) == procName. */
+
+	if (!p->argv0)
+		return 0;
+
+	argv1idx = strlen(p->argv0) + 1;
+	if (argv1idx >= p->argv_len)
+		return 0;
+
+	if (strcmp(bb_basename(p->argv0 + argv1idx), procName) != 0)
+		return 0;
+
+	return 1;
+}
+
+/* find_pid_by_name()
+ *
+ *  Modified by Vladimir Oleynik for use with libbb/procps.c
+ *  This finds the pid of the specified process.
+ *  Currently, it's implemented by rummaging through
+ *  the proc filesystem.
+ *
+ *  Returns a list of all matching PIDs
+ *  It is the caller's duty to free the returned pidlist.
+ */
+pid_t* FAST_FUNC find_pid_by_name(const char *procName)
+{
+	pid_t* pidList;
+	int i = 0;
+	procps_status_t* p = NULL;
+
+	pidList = xzalloc(sizeof(*pidList));
+	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGVN))) {
+		if (comm_match(p, procName)
+		/* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
+		 || (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
+		/* TODO: we can also try /proc/NUM/exe link, do we want that? */
+		) {
+			pidList = xrealloc_vector(pidList, 2, i);
+			pidList[i++] = p->pid;
+		}
+	}
+
+	pidList[i] = 0;
+	return pidList;
+}
+
+pid_t* FAST_FUNC pidlist_reverse(pid_t *pidList)
+{
+	int i = 0;
+	while (pidList[i])
+		i++;
+	if (--i >= 0) {
+		pid_t k;
+		int j;
+		for (j = 0; i > j; i--, j++) {
+			k = pidList[i];
+			pidList[i] = pidList[j];
+			pidList[j] = k;
+		}
+	}
+	return pidList;
+}