FreeCalypso > hg > freecalypso-tools
view loadtools/tpinterf.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 | e7502631a0f9 |
children | 8d7dcfd9df53 |
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/* * Target program interface - this module provides some primitives * for communicating programmatically with loadagent and possibly * other target-utils. This module will be linked by both * fc-loadtool and fc-chainload. */ #include <sys/types.h> #include <sys/time.h> #include <sys/errno.h> #include <stdio.h> #include <string.h> #include <strings.h> #include <stdlib.h> extern int errno; extern int target_fd; /* definition matches ../target-utils/libcommon/cmdentry.c */ #define MAXCMD 527 /* * static buffer between tpinterf_make_cmd and tpinterf_send_cmd * * We store the command with an ending \r\n so we can use it for * matching the received echo as well, hence the sizing of the * buffer. */ static char cmdbuf[MAXCMD+2]; static int cmdlen; static int arg_chars_valid(arg) char *arg; { char *cp; for (cp = arg; *cp; cp++) if (*cp < ' ' || *cp > '~') return(0); return(1); } /* * This function takes a command for the target in argv form and * converts it to a space-separated continuous string which can be * passed as tty "keyboard" input to the target, enforcing length * and character validity limits in the process. The output is * stored in an internal static buffer for subsequent * tpinterf_send_cmd(). * * Return value: 0 if everything OK, or -1 if some constraint is * violated. */ tpinterf_make_cmd(argv) char **argv; { int arglen; char **ap, *dp; dp = cmdbuf; cmdlen = 0; for (ap = argv; *ap; ap++) { arglen = strlen(*ap); if (ap != argv) arglen++; /* separating space */ if (arglen > MAXCMD - cmdlen) return(-1); if (!arg_chars_valid(*ap)) return(-1); if (ap != argv) *dp++ = ' '; strcpy(dp, *ap); dp += strlen(*ap); cmdlen += arglen; } *dp++ = '\r'; *dp = '\n'; return(0); } /* * This function sends the previously-constructed command to the target, * and collects the expected echo. * * Return value: 0 if successful, -1 on errors (timeout or wrong response) */ tpinterf_send_cmd() { char echobuf[MAXCMD+2]; fd_set fds; struct timeval tv; int rcvd, cc; write(target_fd, cmdbuf, cmdlen + 1); for (rcvd = 0; rcvd < cmdlen + 2; ) { FD_ZERO(&fds); FD_SET(target_fd, &fds); tv.tv_sec = 1; tv.tv_usec = 0; cc = select(target_fd+1, &fds, NULL, NULL, &tv); if (cc < 0) { if (errno == EINTR) continue; perror("select"); return(-1); } if (cc < 1) { fprintf(stderr, "error: timeout waiting for command echo\n"); return(-1); } cc = read(target_fd, echobuf + rcvd, cmdlen + 2 - rcvd); if (cc <= 0) { perror("read after successful select"); return(-1); } rcvd += cc; } if (bcmp(echobuf, cmdbuf, cmdlen + 2)) { fprintf(stderr, "error: command echo mismatch\n"); return(-1); } else return(0); } /* * This functions reads the serial output from the target until a * '=' prompt is received. All intermediate output is passed to * stdout. * * Return value: 0 if '=' prompt received immediately, * positive if some scribble came before the prompt, -1 on errors * (timeout, read errors, etc). */ tpinterf_pass_output(timeout) { char buf[512], *cp; fd_set fds; struct timeval tv; int cc, newline = 1, totout = 0; for (;;) { FD_ZERO(&fds); FD_SET(target_fd, &fds); tv.tv_sec = timeout; tv.tv_usec = 0; cc = select(target_fd+1, &fds, NULL, NULL, &tv); if (cc < 0) { if (errno == EINTR) continue; perror("select"); return(-1); } if (cc < 1) { fprintf(stderr, "error: timeout waiting for \'=\' prompt from target\n"); return(-1); } cc = read(target_fd, buf, sizeof buf); if (cc <= 0) { perror("read after successful select"); return(-1); } for (cp = buf; cc; cp++) { cc--; if (*cp == '=' && newline && !cc) return(totout); putchar(*cp); totout++; if (*cp == '\n') newline = 1; else newline = 0; } } }