51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
#include <errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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extern int tty_read(unsigned minor,char * buf,int count);
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extern int tty_write(unsigned minor,char * buf,int count);
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static int rw_ttyx(int rw,unsigned minor,char * buf,int count);
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static int rw_tty(int rw,unsigned minor,char * buf,int count);
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typedef (*crw_ptr)(int rw,unsigned minor,char * buf,int count);
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#define NRDEVS ((sizeof (crw_table))/(sizeof (crw_ptr)))
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static crw_ptr crw_table[]={
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NULL, /* nodev */
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NULL, /* /dev/mem */
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NULL, /* /dev/fd */
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NULL, /* /dev/hd */
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rw_ttyx, /* /dev/ttyx */
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rw_tty, /* /dev/tty */
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NULL, /* /dev/lp */
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NULL}; /* unnamed pipes */
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static int rw_ttyx(int rw,unsigned minor,char * buf,int count)
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{
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return ((rw==READ)?tty_read(minor,buf,count):
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tty_write(minor,buf,count));
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}
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static int rw_tty(int rw,unsigned minor,char * buf,int count)
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{
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if (current->tty<0)
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return -EPERM;
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return rw_ttyx(rw,current->tty,buf,count);
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}
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int rw_char(int rw,int dev, char * buf, int count)
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{
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crw_ptr call_addr;
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if (MAJOR(dev)>=NRDEVS)
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panic("rw_char: dev>NRDEV");
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if (!(call_addr=crw_table[MAJOR(dev)])) {
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printk("dev: %04x\n",dev);
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panic("Trying to r/w from/to nonexistent character device");
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}
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return call_addr(rw,MINOR(dev),buf,count);
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}
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