mars-nwe/examples/unxcomm.c

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/* unxcomm.c 24-Oct-96 */
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/* simple UNX program to work together with 'comm' */
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/* to domonstrate usage of pipefilesystem */
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#include <stdio.h>
#include <fcntl.h>
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#include <sys/time.h>
#include <sys/types.h>
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static char **build_argv(int bufsize, char *command, int len)
/* routine returns **argv for use with execv routines */
{
int offset = ((len+4) / 4) * 4; /* aligned offset for **argv */
int components = (bufsize - offset) / 4;
if (components-- > 1) { /* minimal argv[0] + NULL */
char **argv = (char **)(command+offset);
char **pp = argv;
char *p = command;
char c;
int i=0;
*pp = p;
*(p+len) = 0;
while ((0 != (c = *p++)) && i < components) {
if (c == 10 || c == 13) {
*(p-1) = '\0';
break;
} else if (c == 32 || c == '\t') {
*(p-1) = '\0';
if (*p != 32 && *p != '\t' && *p != 10 && *p != 13) {
*(++pp)=p;
i++;
}
} else if (!i && c == '/') { /* here i must get argv[0] */
*pp=p;
}
}
if (*pp && !**pp) *pp=NULL;
else
*(++pp)=NULL;
return(argv);
}
return(NULL);
}
#define MAXARGLEN 1024
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int bl_read(int fd, void *buf, int size)
{
fd_set fdin;
struct timeval t;
int result;
FD_ZERO(&fdin);
FD_SET(fd, &fdin);
t.tv_sec = 1; /* 1 sec should be enough */
t.tv_usec = 0;
result = select(fd+1, &fdin, NULL, NULL, &t);
if (result > 0)
result=read(fd, buf, size);
return(result);
}
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int main(int argc, char *argv[])
{
int size;
char buf[MAXARGLEN+1024];
close(2);
dup2(1,2);
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if (0 < (size=bl_read(0, buf, MAXARGLEN))){
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char **argvv=build_argv(sizeof(buf), buf, size);
if (argvv) {
char path[300];
execv(buf, argvv);
sprintf(path, "/usr/bin/%s", *argvv);
execv(path, argvv);
sprintf(path, "/bin/%s", *argvv);
execv(path, argvv);
sprintf(path, "/usr/sbin/%s", *argvv);
execv(path, argvv);
sprintf(path, "/sbin/%s", *argvv);
execv(path, argvv);
fprintf(stderr, "%s:\tCould not find program '%s'\n", *argv, buf);
exit(1);
}
}
fprintf(stderr, "%s:\tGot no paras\n", *argv);
exit(1);
}