void executeCommand(struct command *c)
{
int i, first, n;
int fds[2], nextHasReadPipe = 0;
char **args;
pid_t child;
struct command *p;
struct argument *a;
struct redirection *tail, *r;
/* Walk through the list and:
* 1) resolve redirections to files
* 2) set up pipes and add them as redirections
*/
for(p = c; p; p = p->next)
{
if(p->redir)
resolveRedirections(p->redir);
/* Pipe setup */
tail = NULL;
if(nextHasReadPipe)
{
/* Set up the read end of the previous pipe */
r = safeMalloc(sizeof(struct redirection));
r->filename = NULL;
r->mode = READ | PIPE;
r->fromfd = 0;
r->tofd = fds[0];
r->next = NULL;
/* Add to the redirections list */
if(!p->redir)
p->redir = tail = r;
else
{
/* Find the tail */
tail = p->redir;
while(tail->next)
tail = tail->next;
tail->next = r;
tail = r;
}
nextHasReadPipe = 0;
}
if(p->next && (p->mode & PIPED))
{
/* Create pipe */
pipe(fds);
/* Set up the write end */
r = safeMalloc(sizeof(struct redirection));
r->filename = NULL;
r->mode = WRITE | PIPE;
r->fromfd = 1;
r->tofd = fds[1];
r->next = NULL;
/* Add to the redirections list */
if(!p->redir)
p->redir = r;
else
{
if(!tail)
{
/* Find the tail */
tail = p->redir;
while(tail->next)
tail = tail->next;
}
tail->next = r;
}
nextHasReadPipe = 1;
}
}
/* Now walk through the list and fork processes */
i = 0;
first = 1;
for(p = c; p; p = p->next)
{
child = fork();
if(child < 0)
{
perror("fork");
exit(EXIT_FAILURE);
}
if(child > 0)
/* Parent process */
p->pid = child;
else
{
/* Child process */
if(p->redir)
setupRedirections(p->redir);
closeOtherPipes(c, p);
/* Count the number of arguments */
n = 0;
for(a = c->firstArg; a; a = a->next)
n++;
/* Allocate and fill args array */
args = safeMalloc((n + 1)*sizeof(char *));
for(n = 0, a = p->firstArg; a; n++, a = a->next)
args[n] = a->s;
args[n] = NULL;
execvp(args[0], args);
/* If we're alive here, execvp() failed */
perror(args[0]);
exit(EXIT_FAILURE);
}
first = 0;
}
/* Close pipes in the parent */
closeOtherPipes(c, NULL);
}
int runCommand(struct job newJob, struct jobSet * jobList,
int inBg) {
struct job * job;
char * newdir, * buf;
int i, len;
int nextin, nextout;
int pipefds[2]; /* pipefd[0] is for reading */
char * statusString;
int jobNum;
/* handle built-ins here -- we don't fork() so we can't background
these very easily */
if (!strcmp(newJob.progs[0].argv[0], "exit")) {
/* this should return a real exit code */
exit(0);
} else if (!strcmp(newJob.progs[0].argv[0], "pwd")) {
len = 50;
buf = malloc(len);
while (!getcwd(buf, len) && errno == ERANGE) {
len += 50;
buf = realloc(buf, len);
}
printf("%s\n", buf);
free(buf);
return 0;
} else if (!strcmp(newJob.progs[0].argv[0], "cd")) {
if (!newJob.progs[0].argv[1] == 1)
newdir = getenv("HOME");
else
newdir = newJob.progs[0].argv[1];
if (chdir(newdir))
printf("failed to change current directory: %s\n",
strerror(errno));
return 0;
} else if (!strcmp(newJob.progs[0].argv[0], "jobs")) {
for (job = jobList->head; job; job = job->next) {
if (job->runningProgs == job->stoppedProgs)
statusString = "Stopped";
else
statusString = "Running";
printf(JOB_STATUS_FORMAT, job->jobId, statusString,
job->text);
}
return 0;
} else if (!strcmp(newJob.progs[0].argv[0], "fg") ||
!strcmp(newJob.progs[0].argv[0], "bg")) {
if (!newJob.progs[0].argv[1] || newJob.progs[0].argv[2]) {
fprintf(stderr, "%s: exactly one argument is expected\n",
newJob.progs[0].argv[0]);
return 1;
}
if (sscanf(newJob.progs[0].argv[1], "%%%d", &jobNum) != 1) {
fprintf(stderr, "%s: bad argument '%s'\n",
newJob.progs[0].argv[0], newJob.progs[0].argv[1]);
return 1;
}
for (job = jobList->head; job; job = job->next)
if (job->jobId == jobNum) break;
if (!job) {
fprintf(stderr, "%s: unknown job %d\n",
newJob.progs[0].argv[0], jobNum);
return 1;
}
if (*newJob.progs[0].argv[0] == 'f') {
/* Make this job the foreground job */
if (tcsetpgrp(0, job->pgrp))
perror("tcsetpgrp");
jobList->fg = job;
}
/* Restart the processes in the job */
for (i = 0; i < job->numProgs; i++)
job->progs[i].isStopped = 0;
kill(-job->pgrp, SIGCONT);
job->stoppedProgs = 0;
return 0;
}
nextin = 0, nextout = 1;
for (i = 0; i < newJob.numProgs; i++) {
if ((i + 1) < newJob.numProgs) {
pipe(pipefds);
nextout = pipefds[1];
} else {
nextout = 1;
}
if (!(newJob.progs[i].pid = fork())) {
signal(SIGTTOU, SIG_DFL);
if (nextin != 0) {
dup2(nextin, 0);
close(nextin);
}
if (nextout != 1) {
dup2(nextout, 1);
close(nextout);
}
/* explicit redirections override pipes */
setupRedirections(newJob.progs + i);
execvp(newJob.progs[i].argv[0], newJob.progs[i].argv);
fprintf(stderr, "exec() of %s failed: %s\n",
newJob.progs[i].argv[0],
strerror(errno));
exit(1);
}
/* put our child in the process group whose leader is the
first process in this pipe */
setpgid(newJob.progs[i].pid, newJob.progs[0].pid);
if (nextin != 0) close(nextin);
if (nextout != 1) close(nextout);
/* If there isn't another process, nextin is garbage
but it doesn't matter */
nextin = pipefds[0];
}
newJob.pgrp = newJob.progs[0].pid;
/* find the ID for the job to use */
newJob.jobId = 1;
for (job = jobList->head; job; job = job->next)
if (job->jobId >= newJob.jobId)
newJob.jobId = job->jobId + 1;
/* add the job to the list of running jobs */
if (!jobList->head) {
job = jobList->head = malloc(sizeof(*job));
} else {
for (job = jobList->head; job->next; job = job->next);
job->next = malloc(sizeof(*job));
job = job->next;
}
*job = newJob;
job->next = NULL;
job->runningProgs = job->numProgs;
job->stoppedProgs = 0;
if (inBg) {
/* we don't wait for background jobs to return -- append it
to the list of backgrounded jobs and leave it alone */
printf("[%d] %d\n", job->jobId,
newJob.progs[newJob.numProgs - 1].pid);
} else {
jobList->fg = job;
/* move the new process group into the foreground */
if (tcsetpgrp(0, newJob.pgrp))
perror("tcsetpgrp");
}
return 0;
}
