Rich Felker suggested removing dprintf() from watch, and one thing led to

another... This adds bb_xspawn() support, which does vfork/exec.  (I don't
know why using a static instead of a local adds ~40 bytes, but using
the local doesn't work...)
This commit is contained in:
Rob Landley 2006-05-25 23:02:40 +00:00
parent 69d863b6c6
commit 399d2b5c24
3 changed files with 58 additions and 62 deletions

View File

@ -4,20 +4,7 @@
*
* Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* BB_AUDIT SUSv3 N/A */
@ -41,23 +28,18 @@
int watch_main(int argc, char **argv)
{
const int header_len = 40;
time_t t;
pid_t pid;
int width, len;
unsigned period = 2;
int old_stdout;
int len, len2;
char **watched_argv;
char header[header_len + 1];
char **watched_argv, *header;
if (argc < 2) {
bb_show_usage();
}
if (argc < 2) bb_show_usage();
get_terminal_width_height(1, &width, 0);
header = xzalloc(width--);
/* don't use getopt, because it permutes the arguments */
++argv;
if ((argc > 3) && !strcmp(*argv, "-n")
) {
if ((argc > 3) && !strcmp(*argv, "-n")) {
period = bb_xgetularg10_bnd(argv[1], 1, UINT_MAX);
argv += 2;
}
@ -65,44 +47,22 @@ int watch_main(int argc, char **argv)
/* create header */
len = snprintf(header, header_len, "Every %ds:", period);
/* Don't bother checking for len < 0, as it should never happen.
* But, just to be prepared... */
assert(len >= 0);
do {
len2 = strlen(*argv);
if (len + len2 >= header_len-1) {
break;
}
header[len] = ' ';
memcpy(header+len+1, *argv, len2);
len += len2+1;
} while (*++argv);
header[len] = 0;
/* thanks to lye, who showed me how to redirect stdin/stdout */
old_stdout = dup(STDOUT_FILENO);
len = snprintf(header, width, "Every %ds:", period);
while (*argv && len<width)
snprintf(header+len, width-len, " %s", *(argv++));
while (1) {
time(&t);
/* Use dprintf to avoid fflush()ing stdout. */
if (dprintf(1, "\033[H\033[J%-*s%s\n", header_len, header, ctime(&t)) < 0) {
bb_perror_msg_and_die("printf");
}
char *thyme;
time_t t;
pid = vfork(); /* vfork, because of ucLinux */
if (pid > 0) {
//parent
wait(0);
time(&t);
thyme = ctime(&t);
len = strlen(thyme);
if (len < width) header[width-len] = 0;
printf("\033[H\033[J%s %s\n", header, thyme);
waitpid(bb_xspawn(watched_argv),0,0);
sleep(period);
} else if (0 == pid) {
//child
dup2(old_stdout, STDOUT_FILENO);
execvp(*watched_argv, watched_argv);
bb_perror_msg_and_die("%s", *watched_argv);
} else {
bb_perror_msg_and_die("vfork");
}
}
}

View File

@ -146,6 +146,8 @@ extern void bb_fflush_stdout_and_exit(int retval) ATTRIBUTE_NORETURN;
extern void xstat(const char *filename, struct stat *buf);
extern int bb_xsocket(int domain, int type, int protocol);
extern pid_t bb_spawn(char **argv);
extern pid_t bb_xspawn(char **argv);
extern void bb_xdaemon(int nochdir, int noclose);
extern void bb_xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen);
extern void bb_xlisten(int s, int backlog);

View File

@ -182,3 +182,37 @@ void bb_xfflush_stdout(void)
}
}
#endif
#ifdef L_spawn
// This does a fork/exec in one call, using vfork().
pid_t bb_spawn(char **argv)
{
static int failed;
pid_t pid;
// Be nice to nommu machines.
failed = 0;
pid = vfork();
if (pid < 0) return pid;
if (!pid) {
execvp(*argv, argv);
// We're sharing a stack with blocked parent, let parent know we failed
// and then exit to unblock parent (but don't run atexit() stuff, which
// would screw up parent.)
failed = -1;
_exit(0);
}
return failed ? failed : pid;
}
#endif
#ifdef L_xspawn
pid_t bb_xspawn(char **argv)
{
pid_t pid = bb_spawn(argv);
if (pid < 0) bb_perror_msg_and_die("%s", *argv);
return pid;
}
#endif