create common proc_tools

proc_put, proc_get and proc_get_hex are used in many files.
Avoid duplication by moving them to common/proc_tools.c.
Convert azbox's cVideo to use proc_tools.h

common/proc_tools.c

@@ -0,0 +1,59 @@
+/*
+ * helper functions to interact with files, usually in the proc filesystem
+ *
+ * (C) 2012 Stefan Seyfried <seife@tuxboxcvs.slipkontur.de>
+ *
+ * License: GPLv2 or later
+ *
+ */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <ctype.h>	/* isspace */
+#include <stdio.h>	/* sscanf */
+
+#include "proc_tools.h"
+
+int proc_put(const char *path, const char *value, const int len)
+{
+	int ret, ret2;
+	int pfd = open(path, O_WRONLY);
+	if (pfd < 0)
+		return pfd;
+	ret = write(pfd, value, len);
+	ret2 = close(pfd);
+	if (ret2 < 0)
+		return ret2;
+	return ret;
+}
+
+int proc_get(const char *path, char *value, const int len)
+{
+	int ret, ret2;
+	int pfd = open(path, O_RDONLY);
+	if (pfd < 0)
+		return pfd;
+	ret = read(pfd, value, len);
+	value[len-1] = '\0'; /* make sure string is terminated */
+	if (ret >= 0)
+	{
+		while (ret > 0 && isspace(value[ret-1]))
+			ret--;		/* remove trailing whitespace */
+		value[ret] = '\0';	/* terminate, even if ret = 0 */
+	}
+	ret2 = close(pfd);
+	if (ret2 < 0)
+		return ret2;
+	return ret;
+}
+
+unsigned int proc_get_hex(const char *path)
+{
+	unsigned int n, ret = 0;
+	char buf[16];
+	n = proc_get(path, buf, 16);
+	if (n > 0)
+		sscanf(buf, "%x", &ret);
+	return ret;
+}