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/* ISC license. */
#include <string.h>
#include <stdint.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <errno.h>
#include <skalibs/types.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/buffer.h>
#include <skalibs/stralloc.h>
#include <skalibs/genalloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/skamisc.h>
#include <skalibs/avltree.h>
#include "s6-ps.h"
static avltree ttycache_tree = AVLTREE_ZERO ;
static genalloc ttycache_index = GENALLOC_ZERO ;
int s6ps_ttycache_init (void)
{
avltree_init(&ttycache_tree, 5, 3, 8, &left_dtok, &uint32_cmp, &ttycache_index) ;
return 1 ;
}
void s6ps_ttycache_finish (void)
{
avltree_free(&ttycache_tree) ;
genalloc_free(dius_t, &ttycache_index) ;
}
static int check (char const *s, dev_t ttynr)
{
struct stat st ;
if (stat(s, &st) < 0) return 0 ;
return S_ISCHR(st.st_mode) && (st.st_rdev == ttynr) ;
}
/* No blind scanning of all /dev or /sys/devices, kthx */
static int ttyguess (stralloc *sa, dev_t ttynr)
{
unsigned int maj = major(ttynr), min = minor(ttynr) ;
/* Try /dev/tty? and /dev/pts/? */
if (maj == 4 && min < 64)
{
char tmp[11] = "/dev/tty" ;
tmp[uint_fmt(tmp+8, min)] = 0 ;
if (check(tmp, ttynr)) return stralloc_cats(sa, tmp+5) && stralloc_0(sa) ;
}
else if (maj >= 136 && maj < 144)
{
unsigned int n = ((maj - 136) << 20) | min ;
char tmp[9 + UINT_FMT] = "/dev/pts/" ;
tmp[9 + uint_fmt(tmp+9, n)] = 0 ;
if (check(tmp, ttynr)) return stralloc_cats(sa, tmp+5) && stralloc_0(sa) ;
}
/* Use /sys/dev/char/maj:min if it exists */
{
int fd ;
size_t pos = 14 ;
char path[23 + 2 * UINT_FMT] = "/sys/dev/char/" ;
pos += uint_fmt(path + pos, maj) ;
path[pos++] = ':' ;
pos += uint_fmt(path + pos, min) ;
memcpy(path + pos, "/uevent", 8) ;
fd = open_read(path) ;
if (fd >= 0)
{
char buf[4097] ;
buffer b = BUFFER_INIT(&fd_readv, fd, buf, 4097) ;
size_t start = satmp.len ;
int r ;
for (;;)
{
satmp.len = start ;
r = skagetln(&b, &satmp, '\n') ;
if (r <= 0) break ;
if ((satmp.len - start) > 8 && !memcmp(satmp.s + start, "DEVNAME=", 8)) break ;
}
fd_close(fd) ;
if (r > 0)
{
satmp.s[satmp.len - 1] = 0 ;
satmp.len = start ;
memcpy(satmp.s + start + 3, "/dev/", 5) ;
if (check(satmp.s + start + 3, ttynr))
return stralloc_cats(sa, satmp.s + start + 8) && stralloc_0(sa) ;
}
}
}
/* Fallback: print explicit maj:min */
{
size_t pos = 1 ;
char tmp[3 + 2 * UINT_FMT] = "(" ;
pos += uint_fmt(tmp + pos, maj) ;
tmp[pos++] = ':' ;
pos += uint_fmt(tmp + pos, min) ;
tmp[pos++] = ')' ;
tmp[pos++] = 0 ;
return stralloc_catb(sa, tmp, pos) ;
}
}
int s6ps_ttycache_lookup (stralloc *sa, dev_t ttynr)
{
int wasnull = !satmp.s ;
dius_t d = { .left = (uint32_t)ttynr, .right = satmp.len } ;
uint32_t i ;
if (!avltree_search(&ttycache_tree, &d.left, &i))
{
unsigned int n = genalloc_len(dius_t, &ttycache_index) ;
if (!ttyguess(&satmp, ttynr)) return 0 ;
if (!genalloc_append(dius_t, &ttycache_index, &d)) goto err ;
if (!avltree_insert(&ttycache_tree, n))
{
genalloc_setlen(dius_t, &ttycache_index, n) ;
goto err ;
}
i = n ;
}
return stralloc_cats(sa, satmp.s + genalloc_s(dius_t, &ttycache_index)[i].right) ;
err:
{
int e = errno ;
if (wasnull) stralloc_free(&satmp) ;
else satmp.len = d.right ;
errno = e ;
}
return 0 ;
}
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