First pass at writing a shell for busybox.

Works fine, full job control support, etc.
No syntax yet (if, then, while, etc).  Handles
pipes and & processes fine.

TODO: add command editing, add syntax suport.

 -Erik

1 files changed, 915 insertions, 0 deletions

diff --git a/lash.c b/lash.c
new file mode 100644
index 0000000..9e467dc
--- /dev/null
+++ b/lash.c
@@ -0,0 +1,915 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * BusyBox Shell
+ *
+ * Copyright (C) 2000 by Lineo, inc.
+ * Written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>
+ *
+ * Based in part on ladsh.c by Michael K. Johnson and Erik W. Troan, which is
+ * under the following liberal license: "We have placed this source code in the
+ * public domain. Use it in any project, free or commercial."
+ *
+ * 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
+ *
+ */
+
+#include "internal.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <glob.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+
+#define MAX_COMMAND_LEN 250     /* max length of a single command 
+                                   string */
+#define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"
+
+enum redirectionType { REDIRECT_INPUT, REDIRECT_OVERWRITE, REDIRECT_APPEND };
+
+struct jobSet {
+    struct job * head;      /* head of list of running jobs */
+    struct job * fg;        /* current foreground job */
+};
+
+struct redirectionSpecifier {
+    enum redirectionType type;  /* type of redirection */
+    int fd;                 /* file descriptor being redirected */
+    char * filename;        /* file to redirect fd to */
+};
+
+struct childProgram {
+    pid_t pid;              /* 0 if exited */
+    char ** argv;           /* program name and arguments */
+    int numRedirections;    /* elements in redirection array */
+    struct redirectionSpecifier * redirections;  /* I/O redirections */
+    glob_t globResult;      /* result of parameter globbing */
+    int freeGlob;           /* should we globfree(&globResult)? */
+    int isStopped;          /* is the program currently running? */
+};
+
+struct job {
+    int jobId;              /* job number */
+    int numProgs;           /* total number of programs in job */
+    int runningProgs;       /* number of programs running */
+    char * text;            /* name of job */
+    char * cmdBuf;          /* buffer various argv's point into */
+    pid_t pgrp;             /* process group ID for the job */
+    struct childProgram * progs; /* array of programs in job */
+    struct job * next;      /* to track background commands */
+    int stoppedProgs;       /* number of programs alive, but stopped */
+};
+
+struct builtInCommand {
+    char *cmd;              /* name */
+    char *descr;            /* description */
+    char *usage;            /* usage */
+    int (*function) (struct job *, struct jobSet * jobList);   /* function ptr */
+};
+
+/* Some function prototypes */
+static int shell_cd(struct job* cmd, struct jobSet* junk);
+static int shell_env(struct job* dummy, struct jobSet* junk);
+static int shell_exit(struct job* cmd, struct jobSet* junk);
+static int shell_fg_bg(struct job* cmd, struct jobSet* jobList);
+static int shell_help(struct job* cmd, struct jobSet* junk);
+static int shell_jobs(struct job* dummy, struct jobSet* jobList);
+static int shell_pwd(struct job* dummy, struct jobSet* junk);
+static int shell_set(struct job* cmd, struct jobSet* junk);
+static int shell_source(struct job* cmd, struct jobSet* jobList);
+static int shell_unset(struct job* cmd, struct jobSet* junk);
+
+static void checkJobs(struct jobSet * jobList);
+static int getCommand(FILE * source, char * command);
+static int parseCommand(char ** commandPtr, struct job * job, int * isBg);
+static int setupRedirections(struct childProgram * prog);
+static int runCommand(struct job newJob, struct jobSet * jobList, int inBg);
+static int busy_loop(FILE * input);
+
+    
+/* Table of built-in functions */
+static struct builtInCommand bltins[] = {
+	{"bg", "Resume a job in the background", "bg [%%job]", shell_fg_bg},
+	{"cd", "Change working directory", "cd [dir]", shell_cd},
+	{"env", "Print all environment variables", "env", shell_env},
+	{"exit", "Exit from shell()", "exit", shell_exit},
+	{"fg", "Bring job into the foreground", "fg [%%job]", shell_fg_bg},
+	{"jobs", "Lists the active jobs", "jobs", shell_jobs},
+	{"pwd", "Print current directory", "pwd", shell_pwd},
+	{"set", "Set environment variable", "set [VAR=value]", shell_set},
+	{"unset", "Unset environment variable", "unset VAR", shell_unset},
+	//{"echo", "Echo arguments on stdout", "echo arg1 [...]", shell_echo},
+	{".", "Source-in and run commands in a file", ". filename", shell_source},
+	{"help", "List shell built-in commands", "help", shell_help},
+	{NULL, NULL, NULL, NULL}
+};
+
+static const char shell_usage[] =
+	"sh [FILE]...\n\n"
+	"The BusyBox command interpreter (shell).\n\n";
+
+
+static char cwd[1024];
+static char *prompt = "# ";
+
+
+/* built-in 'cd <path>' handler */
+static int shell_cd(struct job* cmd, struct jobSet* junk)
+{
+	char *newdir;
+        if (!cmd->progs[0].argv[1] == 1) 
+            newdir = getenv("HOME");
+        else 
+            newdir = cmd->progs[0].argv[1];
+        if (chdir(newdir)) { 
+            printf("cd: %s: %s\n", newdir, strerror(errno));
+	    return FALSE;
+	}
+	getcwd(cwd, sizeof(cwd));
+
+        return TRUE;
+}
+
+/* built-in 'env' handler */
+static int shell_env(struct job* dummy, struct jobSet* junk)
+{
+	char **e;
+
+	for (e = environ ; *e ; e++) {
+		fprintf(stdout, "%s\n", *e);
+	}
+	return (0);
+}
+
+/* built-in 'exit' handler */
+static int shell_exit(struct job* cmd, struct jobSet* junk)
+{
+        if (!cmd->progs[0].argv[1] == 1) 
+			exit TRUE;
+        else 
+			exit(atoi(cmd->progs[0].argv[1]));
+}
+
+/* built-in 'fg' and 'bg' handler */
+static int shell_fg_bg(struct job* cmd, struct jobSet* jobList)
+{
+	int i, jobNum;
+	struct job* job;
+
+        if (!cmd->progs[0].argv[1] || cmd->progs[0].argv[2]) {
+            fprintf(stderr, "%s: exactly one argument is expected\n",
+                    cmd->progs[0].argv[0]);
+            return FALSE;
+        }
+
+        if (sscanf(cmd->progs[0].argv[1], "%%%d", &jobNum) != 1) {
+            fprintf(stderr, "%s: bad argument '%s'\n",
+                    cmd->progs[0].argv[0], cmd->progs[0].argv[1]);
+            return FALSE;
+        }
+
+        for (job = jobList->head; job; job = job->next) 
+            if (job->jobId == jobNum) break;
+
+        if (!job) {
+            fprintf(stderr, "%s: unknown job %d\n",
+                    cmd->progs[0].argv[0], jobNum);
+            return FALSE;
+        }
+
+        if (*cmd->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 TRUE;
+}
+
+/* built-in 'help' handler */
+static int shell_help(struct job* cmd, struct jobSet* junk)
+{
+	struct builtInCommand *x;
+
+	fprintf(stdout, "\nBuilt-in commands:\n");
+	fprintf(stdout, "-------------------\n");
+	for ( x=bltins; x->cmd; x++) {
+		fprintf(stdout, "%s\t%s\n", x->cmd, x->descr);
+	}
+	fprintf(stdout, "\n\n");
+	return TRUE;
+}
+
+/* built-in 'jobs' handler */
+static int shell_jobs(struct job* dummy, struct jobSet* jobList)
+{
+	struct job * job;
+	char * statusString;
+        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 TRUE;
+}
+
+
+/* built-in 'pwd' handler */
+static int shell_pwd(struct job* dummy, struct jobSet* junk)
+{
+	getcwd(cwd, sizeof(cwd));
+	fprintf(stdout, "%s\n", cwd);
+	return TRUE;
+}
+
+/* built-in 'set VAR=value' handler */
+static int shell_set(struct job* cmd, struct jobSet* junk)
+{
+	int res;
+
+        if (!cmd->progs[0].argv[1] == 1) { 
+		return (shell_env(cmd, junk));
+	}
+	res = putenv(cmd->progs[0].argv[1]);
+	if (res)
+		fprintf(stdout, "set: %s\n", strerror(errno));
+	return (res);
+}
+
+/* Built-in '.' handler (read-in and execute commands from file) */
+static int shell_source(struct job* cmd, struct jobSet* junk)
+{
+	FILE *input;
+	int status;
+        
+	if (!cmd->progs[0].argv[1] == 1) 
+		return FALSE;
+
+	input = fopen(cmd->progs[0].argv[1], "r");
+	if (!input) {
+		fprintf(stdout, "Couldn't open file '%s'\n", cmd->progs[0].argv[1]);
+		return FALSE;
+	}
+
+	/* Now run the file */
+	status = busy_loop(input);
+	return (status);
+}
+
+/* built-in 'unset VAR' handler */
+static int shell_unset(struct job* cmd, struct jobSet* junk)
+{
+        if (!cmd->progs[0].argv[1] == 1) { 
+		fprintf(stdout, "unset: parameter required.\n");
+		return FALSE;
+	}
+	unsetenv(cmd->progs[0].argv[1]);
+	return TRUE;
+}
+
+/* free up all memory from a job */
+static void freeJob(struct job * cmd) 
+{
+    int i;
+
+    for (i = 0; i < cmd->numProgs; i++) {
+        free(cmd->progs[i].argv);
+        if (cmd->progs[i].redirections) free(cmd->progs[i].redirections);
+        if (cmd->progs[i].freeGlob) globfree(&cmd->progs[i].globResult);
+    }
+    free(cmd->progs);
+    if (cmd->text) free(cmd->text);
+    free(cmd->cmdBuf);
+}
+
+/* remove a job from the jobList */
+static void removeJob(struct jobSet * jobList, struct job * job) 
+{
+    struct job * prevJob;
+
+    freeJob(job); 
+    if (job == jobList->head) {
+        jobList->head = job->next;
+    } else {
+        prevJob = jobList->head;
+        while (prevJob->next != job) prevJob = prevJob->next;
+        prevJob->next = job->next;
+    }
+
+    free(job);
+}
+
+/* Checks to see if any background processes have exited -- if they 
+   have, figure out why and see if a job has completed */
+static void checkJobs(struct jobSet * jobList) 
+{
+    struct job * job;
+    pid_t childpid;
+    int status;
+    int progNum=0;
+   
+    while ((childpid = waitpid(-1, &status, WNOHANG | WUNTRACED)) > 0) {
+        for (job = jobList->head; job; job = job->next) {
+            progNum = 0;
+            while (progNum < job->numProgs && 
+                        job->progs[progNum].pid != childpid)
+                progNum++;
+            if (progNum < job->numProgs) break;
+        }
+
+        if (WIFEXITED(status) || WIFSIGNALED(status)) {
+            /* child exited */
+            job->runningProgs--;
+            job->progs[progNum].pid = 0;
+
+            if (!job->runningProgs) {
+                printf(JOB_STATUS_FORMAT, job->jobId, "Done", job->text);
+                removeJob(jobList, job);
+            }
+        } else {
+            /* child stopped */
+            job->stoppedProgs++;
+            job->progs[progNum].isStopped = 1;
+
+            if (job->stoppedProgs == job->numProgs) {
+                printf(JOB_STATUS_FORMAT, job->jobId, "Stopped", job->text);
+            }
+        }
+    }
+
+    if (childpid == -1 && errno != ECHILD)
+        perror("waitpid");
+}
+
+static int getCommand(FILE * source, char * command) 
+{
+    if (source == stdin) {
+		fprintf(stdout, "%s %s", cwd, prompt);
+        fflush(stdout);
+    }
+
+    if (!fgets(command, MAX_COMMAND_LEN, source)) {
+        if (source == stdin) printf("\n");
+        return 1;
+    }
+
+    /* remove trailing newline */
+    command[strlen(command) - 1] = '\0';
+
+    return 0;
+}
+
+static void globLastArgument(struct childProgram * prog, int * argcPtr,
+                        int * argcAllocedPtr) 
+{
+    int argc = *argcPtr;
+    int argcAlloced = *argcAllocedPtr;
+    int rc;
+    int flags;
+    int i;
+    char * src, * dst;
+
+    if (argc > 1) {             /* cmd->globResult is already initialized */
+        flags = GLOB_APPEND;
+        i = prog->globResult.gl_pathc;
+    } else {
+        prog->freeGlob = 1;
+        flags = 0;
+        i = 0;
+    }
+
+    rc = glob(prog->argv[argc - 1], flags, NULL, &prog->globResult);
+    if (rc == GLOB_NOSPACE) {
+        fprintf(stderr, "out of space during glob operation\n");
+        return;
+    } else if (rc == GLOB_NOMATCH || 
+               (!rc && (prog->globResult.gl_pathc - i) == 1 && 
+                !strcmp(prog->argv[argc - 1], 
+                        prog->globResult.gl_pathv[i]))) {
+        /* we need to remove whatever \ quoting is still present */
+        src = dst = prog->argv[argc - 1];
+        while (*src) {
+            if (*src != '\\') *dst++ = *src;
+            src++;
+        }
+        *dst = '\0';
+    } else if (!rc) {
+        argcAlloced += (prog->globResult.gl_pathc - i);
+        prog->argv = realloc(prog->argv, argcAlloced * sizeof(*prog->argv));
+        memcpy(prog->argv + (argc - 1), prog->globResult.gl_pathv + i,
+                sizeof(*(prog->argv)) * (prog->globResult.gl_pathc - i));
+        argc += (prog->globResult.gl_pathc - i - 1);
+    }
+
+    *argcAllocedPtr = argcAlloced;
+    *argcPtr = argc;
+}
+
+/* Return cmd->numProgs as 0 if no command is present (e.g. an empty
+   line). If a valid command is found, commandPtr is set to point to
+   the beginning of the next command (if the original command had more 
+   then one job associated with it) or NULL if no more commands are 
+   present. */
+static int parseCommand(char ** commandPtr, struct job * job, int * isBg) 
+{
+    char * command;
+    char * returnCommand = NULL;
+    char * src, * buf, * chptr;
+    int argc = 0;
+    int done = 0;
+    int argvAlloced;
+    int i;
+    char quote = '\0';  
+    int count;
+    struct childProgram * prog;
+
+    /* skip leading white space */
+    while (**commandPtr && isspace(**commandPtr)) (*commandPtr)++;
+
+	/* this handles empty lines or leading '#' characters */
+    if (!**commandPtr || (**commandPtr=='#')) {
+        job->numProgs = 0;
+        *commandPtr = NULL;
+        return 0;
+    }
+
+    *isBg = 0;
+    job->numProgs = 1;
+    job->progs = malloc(sizeof(*job->progs));
+
+    /* We set the argv elements to point inside of this string. The 
+       memory is freed by freeJob(). 
+
+       Getting clean memory relieves us of the task of NULL 
+       terminating things and makes the rest of this look a bit 
+       cleaner (though it is, admittedly, a tad less efficient) */
+    job->cmdBuf = command = calloc(1, strlen(*commandPtr) + 1);
+    job->text = NULL;
+
+    prog = job->progs;
+    prog->numRedirections = 0;
+    prog->redirections = NULL;
+    prog->freeGlob = 0;
+    prog->isStopped = 0;
+
+    argvAlloced = 5;
+    prog->argv = malloc(sizeof(*prog->argv) * argvAlloced);
+    prog->argv[0] = job->cmdBuf;
+
+    buf = command;
+    src = *commandPtr;
+    while (*src && !done) {
+        if (quote == *src) {
+            quote = '\0';
+        } else if (quote) {
+            if (*src == '\\') {
+                src++;
+                if (!*src) {
+                    fprintf(stderr, "character expected after \\\n");
+                    freeJob(job);
+                    return 1;
+                }
+
+                /* in shell, "\'" should yield \' */
+                if (*src != quote) *buf++ = '\\';
+            } else if (*src == '*' || *src == '?' || *src == '[' || 
+                       *src == ']')
+                *buf++ = '\\';
+            *buf++ = *src;
+        } else if (isspace(*src)) {
+            if (*prog->argv[argc]) {
+                buf++, argc++;
+                /* +1 here leaves room for the NULL which ends argv */
+                if ((argc + 1) == argvAlloced) {
+                    argvAlloced += 5;
+                    prog->argv = realloc(prog->argv, 
+				    sizeof(*prog->argv) * argvAlloced);
+                }
+                prog->argv[argc] = buf;
+
+                globLastArgument(prog, &argc, &argvAlloced);
+            }
+        } else switch (*src) {
+          case '"':
+          case '\'':
+            quote = *src;
+            break;
+
+          case '#':                         /* comment */
+            done = 1;
+            break;
+
+          case '>':                         /* redirections */
+          case '<':
+            i = prog->numRedirections++;
+            prog->redirections = realloc(prog->redirections, 
+                                sizeof(*prog->redirections) * (i + 1));
+
+            prog->redirections[i].fd = -1;
+            if (buf != prog->argv[argc]) {
+                /* the stuff before this character may be the file number 
+                   being redirected */
+                prog->redirections[i].fd = strtol(prog->argv[argc], &chptr, 10);
+
+                if (*chptr && *prog->argv[argc]) {
+                    buf++, argc++;
+                    globLastArgument(prog, &argc, &argvAlloced);
+                }
+            }
+
+            if (prog->redirections[i].fd == -1) {
+                if (*src == '>')
+                    prog->redirections[i].fd = 1;
+                else
+                    prog->redirections[i].fd = 0;
+            }
+
+            if (*src++ == '>') {
+                if (*src == '>')
+                    prog->redirections[i].type = REDIRECT_APPEND, src++;
+                else 
+                    prog->redirections[i].type = REDIRECT_OVERWRITE;
+            } else {
+                prog->redirections[i].type = REDIRECT_INPUT;
+            }
+
+            /* This isn't POSIX sh compliant. Oh well. */
+            chptr = src;
+            while (isspace(*chptr)) chptr++;
+
+            if (!*chptr) {
+                fprintf(stderr, "file name expected after %c\n", *src);
+                freeJob(job);
+                return 1;
+            }
+
+            prog->redirections[i].filename = buf;
+            while (*chptr && !isspace(*chptr)) 
+                *buf++ = *chptr++;
+
+            src = chptr - 1;                /* we src++ later */
+            prog->argv[argc] = ++buf;
+            break;
+
+          case '|':                         /* pipe */
+            /* finish this command */
+            if (*prog->argv[argc]) argc++;
+            if (!argc) {
+                fprintf(stderr, "empty command in pipe\n");
+                freeJob(job);
+                return 1;
+            }
+            prog->argv[argc] = NULL;
+
+            /* and start the next */
+            job->numProgs++;
+            job->progs = realloc(job->progs, 
+                                 sizeof(*job->progs) * job->numProgs);
+            prog = job->progs + (job->numProgs - 1);
+            prog->numRedirections = 0;
+            prog->redirections = NULL;
+            prog->freeGlob = 0;
+            argc = 0;
+
+            argvAlloced = 5;
+            prog->argv = malloc(sizeof(*prog->argv) * argvAlloced);
+            prog->argv[0] = ++buf;
+
+            src++;
+            while (*src && isspace(*src)) src++;
+
+            if (!*src) {
+                fprintf(stderr, "empty command in pipe\n");
+                return 1;
+            }
+            src--;              /* we'll ++ it at the end of the loop */
+
+            break;
+
+          case '&':                         /* background */
+            *isBg = 1;
+          case ';':                         /* multiple commands */
+            done = 1;
+            returnCommand = *commandPtr + (src - *commandPtr) + 1;
+            break;
+
+          case '\\':
+            src++;
+            if (!*src) {
+                freeJob(job);
+                fprintf(stderr, "character expected after \\\n");
+                return 1;
+            }
+            if (*src == '*' || *src == '[' || *src == ']' || *src == '?')
+                *buf++ = '\\';
+            /* fallthrough */
+          default:
+            *buf++ = *src;
+        }
+
+        src++;
+    }
+
+    if (*prog->argv[argc]) {
+        argc++;
+        globLastArgument(prog, &argc, &argvAlloced);
+    }
+    if (!argc) {
+        freeJob(job);
+        return 0;
+    }
+    prog->argv[argc] = NULL;
+
+    if (!returnCommand) {
+        job->text = malloc(strlen(*commandPtr) + 1);
+        strcpy(job->text, *commandPtr);
+    } else {
+        /* This leaves any trailing spaces, which is a bit sloppy */
+
+        count = returnCommand - *commandPtr;
+        job->text = malloc(count + 1);
+        strncpy(job->text, *commandPtr, count);
+        job->text[count] = '\0';
+    }
+
+    *commandPtr = returnCommand;
+
+    return 0;
+}
+
+static int runCommand(struct job newJob, struct jobSet * jobList, 
+               int inBg) 
+{
+    struct job * job;
+    int i;
+    int nextin, nextout;
+    int pipefds[2];             /* pipefd[0] is for reading */
+    struct builtInCommand *x;
+
+    /* handle built-ins here -- we don't fork() so we can't background
+       these very easily */
+    for( x=bltins ; x->cmd ; x++) {
+		if (!strcmp(newJob.progs[0].argv[0], x->cmd)) {
+			return(x->function(&newJob, jobList));
+		}
+    }
+
+    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);
+			fatalError( "sh: %s: %s\n", newJob.progs[i].argv[0], 
+                    strerror(errno));
+        }
+
+        /* 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;
+}
+
+static int setupRedirections(struct childProgram * prog) 
+{
+    int i;
+    int openfd;
+    int mode=O_RDONLY;
+    struct redirectionSpecifier * redir = prog->redirections;
+
+    for (i = 0; i < prog->numRedirections; i++, redir++) {
+        switch (redir->type) {
+          case REDIRECT_INPUT:
+            mode = O_RDONLY;
+            break;
+          case REDIRECT_OVERWRITE:
+            mode = O_RDWR | O_CREAT | O_TRUNC; 
+            break;
+          case REDIRECT_APPEND:
+            mode = O_RDWR | O_CREAT | O_APPEND;
+            break;
+        }
+
+        openfd = open(redir->filename, mode, 0666);
+        if (openfd < 0) {
+            /* this could get lost if stderr has been redirected, but
+               bash and ash both lose it as well (though zsh doesn't!) */
+            fprintf(stderr, "error opening %s: %s\n", redir->filename,
+                        strerror(errno));
+            return 1;
+        }
+
+        if (openfd != redir->fd) {
+            dup2(openfd, redir->fd);
+            close(openfd);
+        }
+    }
+
+    return 0;
+}
+
+
+static int busy_loop(FILE * input) 
+{
+    char command[MAX_COMMAND_LEN + 1];
+    char * nextCommand = NULL;
+    struct jobSet jobList = { NULL, NULL };
+    struct job newJob;
+    int i;
+    int status;
+    int inBg;
+
+    /* don't pay any attention to this signal; it just confuses 
+       things and isn't really meant for shells anyway */
+    signal(SIGTTOU, SIG_IGN);
+    
+    while (1) {
+        if (!jobList.fg) {
+            /* no job is in the foreground */
+
+            /* see if any background processes have exited */
+            checkJobs(&jobList);
+
+            if (!nextCommand) {
+                if (getCommand(input, command)) break;
+                nextCommand = command;
+            }
+
+            if (!parseCommand(&nextCommand, &newJob, &inBg) &&
+                              newJob.numProgs) {
+                runCommand(newJob, &jobList, inBg);
+            }
+        } else {
+            /* a job is running in the foreground; wait for it */
+            i = 0;
+            while (!jobList.fg->progs[i].pid ||
+                   jobList.fg->progs[i].isStopped) i++;
+
+            waitpid(jobList.fg->progs[i].pid, &status, WUNTRACED);
+
+            if (WIFEXITED(status) || WIFSIGNALED(status)) {
+                /* the child exited */
+                jobList.fg->runningProgs--;
+                jobList.fg->progs[i].pid = 0;
+            
+                if (!jobList.fg->runningProgs) {
+                    /* child exited */
+
+                    removeJob(&jobList, jobList.fg);
+                    jobList.fg = NULL;
+
+                    /* move the shell to the foreground */
+                    if (tcsetpgrp(0, getpid()))
+                        perror("tcsetpgrp");
+                }
+            } else {
+                /* the child was stopped */
+                jobList.fg->stoppedProgs++;
+                jobList.fg->progs[i].isStopped = 1;
+
+                if (jobList.fg->stoppedProgs == jobList.fg->runningProgs) {
+                    printf("\n" JOB_STATUS_FORMAT, jobList.fg->jobId, 
+                                "Stopped", jobList.fg->text);
+                    jobList.fg = NULL;
+                }
+            }
+
+            if (!jobList.fg) {
+                /* move the shell to the foreground */
+                if (tcsetpgrp(0, getpid()))
+                    perror("tcsetpgrp");
+            }
+        }
+    }
+
+    return 0;
+}
+
+
+int shell_main(int argc, char ** argv) 
+{
+    FILE * input = stdin;
+
+    if (argc > 2) {
+		usage( shell_usage);
+    } 
+	/* initialize the cwd */
+	getcwd(cwd, sizeof(cwd));
+
+
+	//if (argv[0] && argv[0][0] == '-') {
+	//	shell_source("/etc/profile");
+	//}
+	
+	if (argc < 2) {
+		fprintf(stdout, "\n\nBusyBox v%s (%s) Built-in shell\n", BB_VER, BB_BT);
+		fprintf(stdout, "Enter 'help' for a list of built-in commands.\n\n");
+	} else {
+        input = fopen(argv[1], "r");
+        if (!input)
+			fatalError("A: Couldn't open file '%s': %s\n", argv[1], strerror(errno));
+//		else
+//			fatalError("Got it.\n");
+		//exit(shell_source(argv[1]));
+    } 
+
+	return (busy_loop( input));
+}