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Diffstat (limited to 'src/libps/s6ps_ttycache.c')
-rw-r--r--src/libps/s6ps_ttycache.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/src/libps/s6ps_ttycache.c b/src/libps/s6ps_ttycache.c
new file mode 100644
index 0000000..27282e7
--- /dev/null
+++ b/src/libps/s6ps_ttycache.c
@@ -0,0 +1,138 @@
+/* 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 ;
+}