FreeCalypso > hg > freecalypso-tools
view uptools/atcmd/smsend_concat.c @ 407:19e5a3e2f9c0
fcup-settime: moved time() retrieval a little closer to the output
A fundamental problem with all simple time transfer tools is that there is
always some delay between the time retrieval on the source system and that
transmitted time being set on the destination, and the resulting time
on the destination system is off by that delay amount. This delay cannot
be fully eliminated when working in a simple environment like ours,
but we should make our best effort to minimize it. In the present case,
moving the atinterf_init() call before the time() retrieval should make
a teensy-tiny improvement.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sat, 11 Aug 2018 21:52:17 +0000 |
parents | 076d533f840d |
children |
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/* * This module contains the messy code for automatic generation and * increment of concat SMS reference numbers. */ #include <sys/types.h> #include <sys/param.h> #include <sys/file.h> #include <sys/time.h> #include <ctype.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include "../../rvinterf/include/exitcodes.h" static int initial_seed() { struct timeval tv; u_char refno, *cp, *endp; gettimeofday(&tv, 0); cp = (u_char *) &tv; endp = cp + sizeof(struct timeval); refno = 0; while (cp < endp) refno ^= *cp++; return refno; } get_concsms_refno_from_host_fs() { char *homedir, statefile[MAXPATHLEN]; int fd, cc; char buf[6]; u_char refno; homedir = getenv("HOME"); if (!homedir) { fprintf(stderr, "error: no HOME= defined, needed for concat SMS refno\n"); exit(ERROR_UNIX); } sprintf(statefile, "%s/.concat_sms_refno", homedir); fd = open(statefile, O_RDWR|O_CREAT, 0666); if (fd < 0) { perror(statefile); exit(ERROR_UNIX); } cc = read(fd, buf, 5); if (cc == 5 && buf[0] == '0' && buf[1] == 'x' && isxdigit(buf[2]) && isxdigit(buf[3]) && buf[4] == '\n') refno = strtoul(buf, 0, 16) + 1; else refno = initial_seed(); sprintf(buf, "0x%02X\n", refno); lseek(fd, 0, SEEK_SET); write(fd, buf, 5); close(fd); return refno; }