diff options
Diffstat (limited to 'src/libps/s6ps_ttycache.c')
-rw-r--r-- | src/libps/s6ps_ttycache.c | 138 |
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 ; +} |