From 58bda5913007f53c91ae60cd22483dd222ea5618 Mon Sep 17 00:00:00 2001 From: Clinton Bunch Date: Fri, 30 Aug 2024 08:06:06 -0500 Subject: 53056: new zsh/random module defining an SRANDOM parameter and zrand_float() and zrand_int() math functions --- Src/Modules/random.c | 322 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 322 insertions(+) create mode 100644 Src/Modules/random.c (limited to 'Src/Modules/random.c') diff --git a/Src/Modules/random.c b/Src/Modules/random.c new file mode 100644 index 000000000..a153d8f64 --- /dev/null +++ b/Src/Modules/random.c @@ -0,0 +1,322 @@ +/* + * random.c - module to access kernel random sources. + * + * This file is part of zsh, the Z shell. + * + * Copyright (c) 2022 Clinton Bunch + * All rights reserved. + * + * Permission is hereby granted, without written agreement and without + * license or royalty fees, to use, copy, modify, and distribute this + * software and to distribute modified versions of this software for any + * purpose, provided that the above copyright notice and the following + * two paragraphs appear in all copies of this software. + * + * In no event shall Clinton Bunch or the Zsh Development Group be liable + * to any party for direct, indirect, special, incidental, or consequential + * damages arising out of the use of this software and its documentation, + * even if Clinton Bunch and the Zsh Development Group have been advised of + * the possibility of such damage. + * + * Clinton Bunch and the Zsh Development Group specifically disclaim any + * warranties, including, but not limited to, the implied warranties of + * merchantability and fitness for a particular purpose. The software + * provided hereunder is on an "as is" basis, and Clinton Bunch and the + * Zsh Development Group have no obligation to provide maintenance, + * support, updates, enhancements, or modifications. + * + */ + +#include "random.mdh" + +#include +#include +#include +#include +#include + +#include + +#ifdef HAVE_SYS_RANDOM_H +#include +#endif + +/* Simplify select URANDOM specific code */ +#if !defined(HAVE_ARC4RANDOM_BUF) && !defined(HAVE_GETRANDOM) +#define USE_URANDOM +#endif + +/* buffer to pre-load integers for SRANDOM to lessen the context switches */ +static uint32_t rand_buff[8]; +static int buf_cnt = -1; + +#ifdef USE_URANDOM +/* File descriptor for /dev/urandom */ +int randfd = -1; +#endif /* USE_URANDOM */ + +static zlong get_srandom(UNUSED(Param p)); + +/**/ +ssize_t +getrandom_buffer(void *buf, size_t len) +{ + ssize_t ret; + size_t val = 0; + uint8_t *bufptr = buf; + + do { + errno = 0; +#ifdef HAVE_ARC4RANDOM_BUF + arc4random_buf(buf,len); + ret = len; +#elif defined(HAVE_GETRANDOM) + ret=getrandom(bufptr,(len - val),0); +#else + ret=read(randfd,bufptr,(len - val)); +#endif + if (ret < 0) { + if (errno != EINTR || errflag || retflag || breaks || contflag) { + zwarn("Unable to get random data: %e.", errno); + return -1; + } + } + bufptr += ret; + val += ret; + } while (ret < len); + return ret; +} + +/* + * Generate count number of random 32-bit integers between 0 and max-1 + * Got this algorithm from + *https://lemire.me/blog/2016/06/30/fast-random-shuffling/ + * adapting the public domain code. + * + */ + +/**/ +void +get_bound_random_buffer(uint32_t *buffer, size_t count, uint32_t max) +{ + uint64_t multi_result; + uint32_t threshold; + uint32_t leftover; + + size_t i; /* loop counter */ + + getrandom_buffer((void*) buffer, count*sizeof(uint32_t)); + if (max == UINT32_MAX) + return; + + for(i=0;i> 32; + } +} + +/* + * Provides for the SRANDOM parameter and returns an unsigned 32-bit random + * integer. + */ + +/**/ +static zlong +get_srandom(UNUSED(Param pm)) { + + if(buf_cnt <= 0) { + getrandom_buffer((void*) rand_buff,sizeof(rand_buff)); + buf_cnt=sizeof(rand_buff)/sizeof(rand_buff[0]); + } + return rand_buff[--buf_cnt]; +} + +/* + * Implements math function zrand_int takes 0 to 3 arguments an upper bound, + * a lower bound and a flag as to whether the range is inclusive or not. The + * default is exclusive. If neither upper or lower is specified this is no + * different than SRANDOM. + */ + +/**/ +static mnumber +math_zrand_int(UNUSED(char *name), int argc, mnumber *argv, UNUSED(int id)) +{ + mnumber ret; + uint32_t i; + zlong lower=0, upper=UINT32_MAX,incl=0, diff; + + ret.type = MN_INTEGER; + + switch (argc) { + case 0: ret.u.l=get_srandom(NULL); + return ret; + break; + case 3: incl = (argv[2].u.l != 0)?1:0; + case 2: lower = argv[1].u.l; + case 1: upper = argv[0].u.l; + default: diff = upper-lower+incl; + } + + if (lower < 0 || lower >= UINT32_MAX) { + zwarn("Lower bound (%z) out of range: 0-4294967295",lower); + } else if (upper < lower) { + zwarn("Upper bound (%z) must be greater than Lower Bound (%z)",upper,lower); + } else if (upper < 0 || upper >= UINT32_MAX) { + zwarn("Upper bound (%z) out of range: 0-4294967295",upper); + } + + if ( diff == 0 ) { + ret.u.l=upper; /* still not convinced this shouldn't be an error. */ + } else { + get_bound_random_buffer(&i,1,(uint32_t) diff); + ret.u.l=i+lower; + } + return ret; +} + +/* + * Implements the mathfunc zrand_float and returns a random floating-point + * number between 0 and 1. + * + */ + +/**/ +static mnumber +math_zrand_float(UNUSED(char *name), UNUSED(int argc), UNUSED(mnumber *argv), + UNUSED(int id)) +{ + mnumber ret; + double r; + + r = random_real(); + if (r < 0) { + zwarnnam(name, "Failed to get sufficient random data."); + } + ret.type = MN_FLOAT; + ret.u.d = r; + + return ret; +} + +static const struct gsu_integer srandom_gsu = +{ get_srandom, nullintsetfn, stdunsetfn }; + +static struct paramdef patab[] = { + {"SRANDOM", PM_INTEGER | PM_READONLY_SPECIAL | PM_HIDEVAL, NULL, + &srandom_gsu, NULL, NULL, NULL}, +}; + +static struct mathfunc mftab[] = { + NUMMATHFUNC("zrand_float", math_zrand_float, 0, 0, 0), + NUMMATHFUNC("zrand_int", math_zrand_int, 0, 3, 0), +}; + +static struct features module_features = { + NULL, 0, + NULL, 0, + mftab, sizeof(mftab)/sizeof(*mftab), + patab, sizeof(patab)/sizeof(*patab), + 0 +}; + +/**/ +int +setup_(UNUSED(Module m)) +{ +#ifdef USE_URANDOM + /* Check for the existence of /dev/urandom */ + + struct stat st; + + errno=0; + if (stat("/dev/urandom",&st) < 0) { + zwarn("Error getting kernel random pool: %e.", errno); + return 1; + } + + errno=0; + if (!(S_ISCHR(st.st_mode)) ) { + zwarn("Error getting kernel random pool: %e.", errno); + return 1; + } +#endif /* USE_URANDOM */ + return 0; +} + +/**/ +int +features_(Module m, char ***features) +{ + *features = featuresarray(m, &module_features); + return 0; +} + +/**/ +int +enables_(Module m, int **enables) +{ + return handlefeatures(m, &module_features, enables); +} + +/**/ +int +boot_(UNUSED(Module m)) +{ +#ifdef USE_URANDOM + /* + * Open /dev/urandom. Here because of a weird issue on HP-UX 11.31 + * When opening in setup_ open returned 0. In boot_, it returns + * an unused file descriptor. Decided against ifdef HPUX as it works + * here just as well for other platforms. + * + */ + + int tmpfd=-1; + + errno=0; + if ((tmpfd = open("/dev/urandom", O_RDONLY)) < 0) { + zwarn("Could not access kernel random pool: %e.",errno); + return 1; + } + randfd = movefd(tmpfd); + addmodulefd(randfd,FDT_MODULE); + if (randfd < 0) { + zwarn("Could not access kernel random pool."); + return 1; + } +#endif /* USE_URANDOM */ + return 0; +} + +/**/ +int +cleanup_(Module m) +{ + return setfeatureenables(m, &module_features, NULL); +} + +/**/ +int +finish_(UNUSED(Module m)) +{ +#ifdef USE_URANDOM + if (randfd >= 0) + zclose(randfd); +#endif /* USE_URANDOM */ + return 0; +} -- cgit 1.4.1