[CRIU] [PATCH 1/2] crtools: implement BSD-style setproctitle()

[Ruslan Kuprieiev]

This will allow us to have much informative ps output.

Signed-off-by: Ruslan Kuprieiev <kupruser at gmail.com>
---
 Makefile.crtools       |   1 +
 include/setproctitle.h |  25 ++++++++++++
 setproctitle.c         | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 include/setproctitle.h
 create mode 100644 setproctitle.c

diff --git a/Makefile.crtools b/Makefile.crtools
index 6effc3e..f13b0d2 100644
--- a/Makefile.crtools
+++ b/Makefile.crtools
@@ -62,6 +62,7 @@ obj-y	+= $(ARCH_DIR)/vdso.o
 obj-y	+= cr-service.o
 obj-y	+= sd-daemon.o
 obj-y	+= plugin.o
+obj-y	+= setproctitle.o
 
 ifneq ($(MAKECMDGOALS),clean)
 incdeps := y
diff --git a/include/setproctitle.h b/include/setproctitle.h
new file mode 100644
index 0000000..a4a6ca7
--- /dev/null
+++ b/include/setproctitle.h
@@ -0,0 +1,25 @@
+#ifndef __CR_SETPROCTITLE_H__
+#define __CR_SETPROCTITLE_H__
+
+/*
+ * setproctitle_init() and setproctitle() are implementing BSD-style
+ * setproctitle() for Linux.
+ *
+ * Call setproctitle_init() once before using setproctitle().
+ * This function moves argv and environ out of the way to make maximum space
+ * for process title which is stored in the argv[0].
+ * Upon successful return, this function returns new argv to use. On fail,
+ * this function returns NULL.
+ * DON'T USE OLD ARGV AFTER CALLING THIS FUNCTION!
+ *
+ * setproctitle() sets the process title that appears on the ps(1) command.
+ * If args is NULL, the process title is restored.
+ * If new title begins with '-' character, the executable name is skipped.
+ */
+
+extern char **environ;
+
+char **setproctitle_init(int argc, char **argv);
+void setproctitle(const char *fmt, ...);
+
+#endif /* __CR_SETPROCTITLE_H__ */
diff --git a/setproctitle.c b/setproctitle.c
new file mode 100644
index 0000000..e1d5443
--- /dev/null
+++ b/setproctitle.c
@@ -0,0 +1,106 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include "xmalloc.h"
+#include "setproctitle.h"
+
+static char *title;
+static size_t max_title;
+static char *orig_title;
+
+char **setproctitle_init(int argc, char **argv)
+{
+	int i;
+	int environ_size;
+	char *end = NULL;
+	char **new_environ;
+	char **new_argv;
+
+	/*
+	 * Sanity check.
+	 */
+	if ((argc < 1) || !argv || !environ)
+		return NULL;
+
+	/*
+	 * Check for contiguous argv strings.
+	 */
+	for (i = 0; i < argc; i++)
+		if ((i == 0) || (end + 1 == argv[i]))
+			end = argv[i] + strlen(argv[i]);
+
+	/*
+	 * Check for contiguous environ strings following argv.
+	 */
+	for (i = 0; environ[i] != NULL; i++)
+		if (end + 1 == environ[i])
+			end = environ[i] + strlen(environ[i]);
+
+	environ_size = i;
+
+	max_title = end - argv[0];
+
+	/*
+	 * Move environ.
+	 */
+	new_environ = xmalloc((environ_size + 1)*sizeof(char *));
+
+	for (i = 0; i < environ_size; i++)
+		new_environ[i] = xstrdup(environ[i]);
+
+	new_environ[environ_size] = NULL;
+
+	environ = new_environ;
+
+	/*
+	 * Move argv.
+	 */
+	new_argv = xmalloc((argc + 1)*sizeof(char *));
+
+	for (i = 0; i < argc; i++)
+		new_argv[i] = xstrdup(argv[i]);
+
+	new_argv[argc] = NULL;
+
+	/*
+	 * Save original title.
+	 */
+	orig_title	= xstrdup(argv[0]);
+	title		= argv[0];
+
+	return new_argv;
+}
+
+void setproctitle(const char *fmt, ...)
+{
+	va_list ap;
+	size_t current;
+
+	/*
+	 * Sanity check.
+	 */
+	if (!title || !orig_title)
+		return;
+
+	/*
+	 * Fill all available space with '\0' to avoid old chunks in the title.
+	 */
+	memset(title, '\0', max_title);
+
+	if (!fmt) {
+		snprintf(title, max_title, "%s", orig_title);
+		return;
+	}
+
+	va_start(ap, fmt);
+
+	if (fmt[0] == '-')
+		vsnprintf(title, max_title, &fmt[1], ap);
+	else {
+		current = snprintf(title, max_title, "%s ", orig_title);
+
+		if (current < max_title)
+			vsnprintf(title+current, max_title-current, fmt, ap);
+	}
+
+	va_end(ap);
+}
-- 
1.8.3.2