From 8647a3478674979cca582774168a6f220de171ef Mon Sep 17 00:00:00 2001 From: Jose Bollo Date: Thu, 6 Sep 2018 16:01:20 +0200 Subject: [PATCH] afb-session: Use ad-hoc pseudo-random uuid The use of the generator given by the lib uuid implies the use of the system call 'getrandom' without the flag GRND_NONBLOCK. It has a weird effect on boot because many binders require the generation of uuid at the same time but getrandom is subject to starving. This introduced a tiny pseudo-random generation of UUID that does not implies the use of 'getrandom'. Bug-AGL: SPEC-1655 Change-Id: I5131072881d7a53f0edda9e36762985c96a04550 Signed-off-by: Jose Bollo --- src/afb-session.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/src/afb-session.c b/src/afb-session.c index adfed2ad..fdc88fdf 100644 --- a/src/afb-session.c +++ b/src/afb-session.c @@ -26,6 +26,7 @@ #include #include #include +#include #include "afb-session.h" #include "afb-hook.h" @@ -106,7 +107,56 @@ static inline time_t time_now() static void new_uuid(char uuid[SIZEUUID]) { uuid_t newuuid; + +#if defined(USE_UUID_GENERATE) uuid_generate(newuuid); +#else + struct timespec ts; + static uint16_t pid; + static uint16_t counter; + static char state[32]; + static struct random_data rdata; + + int32_t x; + clock_gettime(CLOCK_MONOTONIC_RAW, &ts); + if (pid == 0) { + pid = (uint16_t)getpid(); + counter = (uint16_t)(ts.tv_nsec >> 8); + rdata.state = NULL; + initstate_r((((unsigned)pid) << 16) + ((unsigned)counter), + state, sizeof state, &rdata); + } + ts.tv_nsec ^= (long)ts.tv_sec; + if (++counter == 0) + counter = 1; + + newuuid[0] = (char)(ts.tv_nsec >> 24); + newuuid[1] = (char)(ts.tv_nsec >> 16); + newuuid[2] = (char)(ts.tv_nsec >> 8); + newuuid[3] = (char)(ts.tv_nsec); + + newuuid[4] = (char)(pid >> 8); + newuuid[5] = (char)(pid); + + random_r(&rdata, &x); + newuuid[6] = (char)(((x >> 16) & 0x0f) | 0x40); /* pseudo-random version */ + newuuid[7] = (char)(x >> 8); + + random_r(&rdata, &x); + newuuid[8] = (char)(((x >> 16) & 0x3f) | 0x80); /* variant RFC4122 */ + newuuid[9] = (char)(x >> 8); + + random_r(&rdata, &x); + newuuid[10] = (char)(x >> 16); + newuuid[11] = (char)(x >> 8); + + random_r(&rdata, &x); + newuuid[12] = (char)(x >> 16); + newuuid[13] = (char)(x >> 8); + + newuuid[14] = (char)(counter >> 8); + newuuid[15] = (char)(counter); +#endif uuid_unparse_lower(newuuid, uuid); } -- 2.16.6