cregit-Linux how code gets into the kernel

Release 4.7 drivers/char/ttyprintk.c

Directory: drivers/char
/*
 *  linux/drivers/char/ttyprintk.c
 *
 *  Copyright (C) 2010  Samo Pogacnik
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the smems of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 */

/*
 * This pseudo device allows user to make printk messages. It is possible
 * to store "console" messages inline with kernel messages for better analyses
 * of the boot process, for example.
 */

#include <linux/device.h>
#include <linux/serial.h>
#include <linux/tty.h>
#include <linux/module.h>


struct ttyprintk_port {
	
struct tty_port port;
	
struct mutex port_write_mutex;
};


static struct ttyprintk_port tpk_port;

/*
 * Our simple preformatting supports transparent output of (time-stamped)
 * printk messages (also suitable for logging service):
 * - any cr is replaced by nl
 * - adds a ttyprintk source tag in front of each line
 * - too long message is fragmeted, with '\'nl between fragments
 * - TPK_STR_SIZE isn't really the write_room limiting factor, bcause
 *   it is emptied on the fly during preformatting.
 */

#define TPK_STR_SIZE 508 
/* should be bigger then max expected line length */

#define TPK_MAX_ROOM 4096 
/* we could assume 4K for instance */

static const char *tpk_tag = "[U] "; 
/* U for User */

static int tpk_curr;


static int tpk_printk(const unsigned char *buf, int count) { static char tmp[TPK_STR_SIZE + 4]; int i = tpk_curr; if (buf == NULL) { /* flush tmp[] */ if (tpk_curr > 0) { /* non nl or cr terminated message - add nl */ tmp[tpk_curr + 0] = '\n'; tmp[tpk_curr + 1] = '\0'; printk(KERN_INFO "%s%s", tpk_tag, tmp); tpk_curr = 0; } return i; } for (i = 0; i < count; i++) { tmp[tpk_curr] = buf[i]; if (tpk_curr < TPK_STR_SIZE) { switch (buf[i]) { case '\r': /* replace cr with nl */ tmp[tpk_curr + 0] = '\n'; tmp[tpk_curr + 1] = '\0'; printk(KERN_INFO "%s%s", tpk_tag, tmp); tpk_curr = 0; if ((i + 1) < count && buf[i + 1] == '\n') i++; break; case '\n': tmp[tpk_curr + 1] = '\0'; printk(KERN_INFO "%s%s", tpk_tag, tmp); tpk_curr = 0; break; default: tpk_curr++; } } else { /* end of tmp buffer reached: cut the message in two */ tmp[tpk_curr + 1] = '\\'; tmp[tpk_curr + 2] = '\n'; tmp[tpk_curr + 3] = '\0'; printk(KERN_INFO "%s%s", tpk_tag, tmp); tpk_curr = 0; } } return count; }

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samo pogacniksamo pogacnik25496.95%150.00%
jiri slabyjiri slaby83.05%150.00%
Total262100.00%2100.00%

/* * TTY operations open function. */
static int tpk_open(struct tty_struct *tty, struct file *filp) { tty->driver_data = &tpk_port; return tty_port_open(&tpk_port.port, tty, filp); }

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samo pogacniksamo pogacnik36100.00%1100.00%
Total36100.00%1100.00%

/* * TTY operations close function. */
static void tpk_close(struct tty_struct *tty, struct file *filp) { struct ttyprintk_port *tpkp = tty->driver_data; mutex_lock(&tpkp->port_write_mutex); /* flush tpk_printk buffer */ tpk_printk(NULL, 0); mutex_unlock(&tpkp->port_write_mutex); tty_port_close(&tpkp->port, tty, filp); }

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samo pogacniksamo pogacnik61100.00%1100.00%
Total61100.00%1100.00%

/* * TTY operations write function. */
static int tpk_write(struct tty_struct *tty, const unsigned char *buf, int count) { struct ttyprintk_port *tpkp = tty->driver_data; int ret; /* exclusive use of tpk_printk within this tty */ mutex_lock(&tpkp->port_write_mutex); ret = tpk_printk(buf, count); mutex_unlock(&tpkp->port_write_mutex); return ret; }

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samo pogacniksamo pogacnik61100.00%1100.00%
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/* * TTY operations write_room function. */
static int tpk_write_room(struct tty_struct *tty) { return TPK_MAX_ROOM; }

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samo pogacniksamo pogacnik14100.00%1100.00%
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/* * TTY operations ioctl function. */
static int tpk_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) { struct ttyprintk_port *tpkp = tty->driver_data; if (!tpkp) return -EINVAL; switch (cmd) { /* Stop TIOCCONS */ case TIOCCONS: return -EOPNOTSUPP; default: return -ENOIOCTLCMD; } return 0; }

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samo pogacniksamo pogacnik59100.00%1100.00%
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static const struct tty_operations ttyprintk_ops = { .open = tpk_open, .close = tpk_close, .write = tpk_write, .write_room = tpk_write_room, .ioctl = tpk_ioctl, }; static const struct tty_port_operations null_ops = { }; static struct tty_driver *ttyprintk_driver;
static int __init ttyprintk_init(void) { int ret = -ENOMEM; mutex_init(&tpk_port.port_write_mutex); ttyprintk_driver = tty_alloc_driver(1, TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_UNNUMBERED_NODE); if (IS_ERR(ttyprintk_driver)) return PTR_ERR(ttyprintk_driver); tty_port_init(&tpk_port.port); tpk_port.port.ops = &null_ops; ttyprintk_driver->driver_name = "ttyprintk"; ttyprintk_driver->name = "ttyprintk"; ttyprintk_driver->major = TTYAUX_MAJOR; ttyprintk_driver->minor_start = 3; ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE; ttyprintk_driver->init_termios = tty_std_termios; ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; tty_set_operations(ttyprintk_driver, &ttyprintk_ops); tty_port_link_device(&tpk_port.port, ttyprintk_driver, 0); ret = tty_register_driver(ttyprintk_driver); if (ret < 0) { printk(KERN_ERR "Couldn't register ttyprintk driver\n"); goto error; } return 0; error: put_tty_driver(ttyprintk_driver); tty_port_destroy(&tpk_port.port); return ret; }

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samo pogacniksamo pogacnik12267.40%114.29%
jiri slabyjiri slaby4323.76%457.14%
darrick j. wongdarrick j. wong94.97%114.29%
dan carpenterdan carpenter73.87%114.29%
Total181100.00%7100.00%


static void __exit ttyprintk_exit(void) { tty_unregister_driver(ttyprintk_driver); put_tty_driver(ttyprintk_driver); tty_port_destroy(&tpk_port.port); }

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takashi iwaitakashi iwai27100.00%1100.00%
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device_initcall(ttyprintk_init); module_exit(ttyprintk_exit); MODULE_LICENSE("GPL");

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samo pogacniksamo pogacnik71486.65%17.69%
jiri slabyjiri slaby516.19%538.46%
takashi iwaitakashi iwai384.61%17.69%
darrick j. wongdarrick j. wong91.09%17.69%
dan carpenterdan carpenter70.85%17.69%
paul gortmakerpaul gortmaker30.36%215.38%
al viroal viro10.12%17.69%
aya mahfouzaya mahfouz10.12%17.69%
Total824100.00%13100.00%
Directory: drivers/char
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