New shell.
This commit is contained in:
rsc
parent
f0d11fea82
commit
1b25f3b057
679
sh.c
679
sh.c
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@ -1,48 +1,141 @@
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// Shell.
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#include "types.h"
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#include "stat.h"
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#include "user.h"
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#include "fcntl.h"
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#define BUFSIZ 512
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#define MAXARGS 10
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#define MAXIO 2
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#define MAXCMD 2
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// Parsed command representation
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#define EXEC 1
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#define REDIR 2
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#define PIPE 3
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#define LIST 4
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#define BACK 5
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// an embarrassingly naive shell
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// some day a real parse tree; for now ad-hoc
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struct ionode {
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int token;
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char *s;
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};
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#define MAXARGS 10
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struct cmd {
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char *argv[MAXARGS];
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char argv0buf[BUFSIZ];
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int argc;
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int token;
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struct ionode iolist[MAXIO];
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struct ionode *io;
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int type;
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};
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struct cmd cmdlist[MAXCMD];
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struct cmd *cmd;
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char buf[BUFSIZ];
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int debug;
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struct execcmd {
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int type;
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char *argv[MAXARGS];
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char *eargv[MAXARGS];
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};
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int parse(char *s);
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void runcmd(void);
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int getcmd(char *buf, int nbuf);
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int ioredirection(struct ionode *iolist, int nio);
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int gettoken(char *s, char **token);
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int _gettoken(char *s, char **p1, char **p2);
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struct redircmd {
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int type;
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struct cmd *cmd;
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char *file;
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char *efile;
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int mode;
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int fd;
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};
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struct pipecmd {
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int type;
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struct cmd *left;
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struct cmd *right;
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};
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struct listcmd {
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int type;
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struct cmd *left;
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struct cmd *right;
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};
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struct backcmd {
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int type;
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struct cmd *cmd;
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};
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struct cmd *parsecmd(char*);
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void panic(char*);
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int
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main(void)
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fork1(void)
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{
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while(getcmd(buf, sizeof(buf)) >= 0) {
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if(parse(buf) >= 0)
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runcmd();
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int pid;
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pid = fork();
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if(pid == -1)
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panic("fork");
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return pid;
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}
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// Execute cmd. Never returns.
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void
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runcmd(struct cmd *cmd)
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{
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int p[2];
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struct backcmd *bcmd;
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struct execcmd *ecmd;
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struct listcmd *lcmd;
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struct pipecmd *pcmd;
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struct redircmd *rcmd;
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if(cmd == 0)
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return;
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switch(cmd->type){
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default:
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panic("runcmd");
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case EXEC:
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ecmd = (struct execcmd*)cmd;
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if(ecmd->argv[0] == 0)
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exit();
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exec(ecmd->argv[0], ecmd->argv);
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printf(2, "exec %s failed\n", ecmd->argv[0]);
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break;
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case REDIR:
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rcmd = (struct redircmd*)cmd;
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close(rcmd->fd);
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if(open(rcmd->file, rcmd->mode) < 0){
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printf(2, "open %s failed\n", rcmd->file);
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exit();
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}
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runcmd(rcmd->cmd);
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break;
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case PIPE:
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pcmd = (struct pipecmd*)cmd;
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if(pipe(p) < 0)
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panic("pipe");
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if(fork1() == 0){
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close(1);
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dup(p[1]);
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close(p[0]);
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close(p[1]);
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runcmd(pcmd->left);
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}
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if(fork1() == 0){
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close(0);
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dup(p[0]);
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close(p[0]);
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close(p[1]);
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runcmd(pcmd->right);
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}
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close(p[0]);
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close(p[1]);
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wait();
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wait();
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break;
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case LIST:
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lcmd = (struct listcmd*)cmd;
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if(fork1() == 0)
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runcmd(lcmd->left);
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wait();
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runcmd(lcmd->right);
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break;
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case BACK:
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bcmd = (struct backcmd*)cmd;
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if(fork1() == 0)
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runcmd(bcmd->cmd);
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break;
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}
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exit();
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}
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@ -59,282 +152,324 @@ getcmd(char *buf, int nbuf)
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}
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int
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parse(char *s)
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main(void)
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{
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char *t;
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int c, i;
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static char buf[100];
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gettoken(s, 0);
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cmd = &cmdlist[0];
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for(i = 0; i < MAXCMD; i++) {
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cmdlist[i].argc = 0;
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cmdlist[i].token = 0;
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cmdlist[i].io = cmdlist[i].iolist;
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}
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for(;;){
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switch((c = gettoken(0, &t))) {
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case 'w': // Add an argument
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if(cmd->argc >= MAXARGS) {
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printf(2, "too many arguments\n");
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return -1;
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}
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cmd->argv[cmd->argc++] = t;
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break;
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case '>': // Input and output redirection
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case '<':
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// Grab the filename from the argument list
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if(gettoken(0, &t) != 'w') {
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printf(2, "syntax error: > not followed by word\n");
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return -1;
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}
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if(cmd->io - cmd->iolist >= MAXIO) {
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printf(2, "too many redirections\n");
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return -1;
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}
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cmd->io->token = c;
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cmd->io->s = t;
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cmd->io++;
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break;
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case ';': // command sequence
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case '|': // pipe
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if(cmd->io - cmd->iolist >= MAXIO) {
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printf(2, "too many redirections\n");
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return -1;
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}
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cmd->token = c;
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cmd++;
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break;
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case 0: // String is complete
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return 0;
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default:
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printf(2, "syntax error: bad return %d from gettoken", c);
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return -1;
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}
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while(getcmd(buf, sizeof(buf)) >= 0) {
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if(fork1() == 0)
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runcmd(parsecmd(buf));
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wait();
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}
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exit();
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}
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void
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runcmd(void)
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panic(char *s)
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{
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int i, r, pid, tfd;
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int fdarray[2];
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struct cmd *c;
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struct ionode *io;
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printf(2, "%s\n", s);
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exit();
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}
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// Return immediately if command line was empty.
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if(cmdlist[0].argc == 0) {
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if(debug)
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printf(2, "EMPTY COMMAND\n");
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return;
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}
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// Constructors
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for(c = &cmdlist[0]; c <= cmd; c++) {
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// Clean up command line.
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// Read all commands from the filesystem: add an initial '/' to
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// the command name.
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// This essentially acts like 'PATH=/'.
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if(c->argv[0][0] != '/') {
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c->argv0buf[0] = '/';
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strcpy(c->argv0buf + 1, c->argv[0]);
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c->argv[0] = c->argv0buf;
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}
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c->argv[c->argc] = 0;
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struct cmd*
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execcmd(void)
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{
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struct execcmd *cmd;
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// Print the command.
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if(debug) {
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printf(2, "[%d] SPAWN:", getpid());
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for(i = 0; c->argv[i]; i++)
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printf(2, " %s", c->argv[i]);
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for(io = c->iolist; io <= c->io; io++) {
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printf(2, "%c %s", io->token, io->s);
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}
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printf(2, "\n");
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}
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cmd = malloc(sizeof(*cmd));
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memset(cmd, 0, sizeof(*cmd));
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cmd->type = EXEC;
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return (struct cmd*)cmd;
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}
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if(strcmp(c->argv[0], "/cd") == 0) {
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if(debug)
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printf (2, "/cd %s is build in\n", c->argv[1]);
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chdir(c->argv[1]);
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return;
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}
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struct cmd*
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redircmd(struct cmd *subcmd, char *file, char *efile, int mode, int fd)
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{
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struct redircmd *cmd;
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if(c->token == '|')
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if(pipe(fdarray) < 0)
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printf(2, "cmd %d pipe failed\n", c);
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cmd = malloc(sizeof(*cmd));
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memset(cmd, 0, sizeof(*cmd));
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cmd->type = REDIR;
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cmd->cmd = subcmd;
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cmd->file = file;
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cmd->efile = efile;
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cmd->mode = mode;
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cmd->fd = fd;
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return (struct cmd*)cmd;
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}
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pid = fork();
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if(pid == 0) {
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if(c->token == '|') {
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if(close(1) < 0)
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printf(2, "close 1 failed\n");
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if((tfd = dup(fdarray[1])) < 0)
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printf(2, "dup failed\n");
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if(close(fdarray[0]) < 0)
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printf(2, "close fdarray[0] failed\n");
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if(close(fdarray[1]) < 0)
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printf(2, "close fdarray[1] failed\n");
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}
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if(c > cmdlist && (c-1)->token == '|') {
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if(close(0) < 0)
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printf(2, "close 0 failed\n");
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if((tfd = dup(fdarray[0])) < 0)
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printf(2, "dup failed\n");
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if(close(fdarray[0]) < 0)
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printf(2, "close fdarray[0] failed\n");
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if(close(fdarray[1]) < 0)
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printf(2, "close fdarray[1] failed\n");
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}
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if(ioredirection(c->iolist, c->io - c->iolist) < 0)
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exit();
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if((r = exec(c->argv0buf, (char**) c->argv)) < 0) {
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printf(2, "exec %s: %d\n", c->argv[0], r);
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exit();
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}
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} else if(pid > 0) {
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int p;
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if(debug)
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printf(2, "[%d] FORKED child %d\n", getpid(), pid);
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struct cmd*
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pipecmd(struct cmd *left, struct cmd *right)
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{
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struct pipecmd *cmd;
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if(c > cmdlist && (c-1)->token == '|') {
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close(fdarray[0]);
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close(fdarray[1]);
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}
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if(c->token != '|') {
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if(debug)
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printf(2, "[%d] WAIT for children\n", getpid());
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do {
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p = wait();
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if(debug)
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printf(2, "[%d] WAIT child %d finished\n", getpid(), p);
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} while(p > 0);
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if(debug)
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printf(2, "[%d] wait finished\n", getpid());
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}
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}
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}
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cmd = malloc(sizeof(*cmd));
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memset(cmd, 0, sizeof(*cmd));
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cmd->type = PIPE;
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cmd->left = left;
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cmd->right = right;
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return (struct cmd*)cmd;
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}
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struct cmd*
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listcmd(struct cmd *left, struct cmd *right)
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{
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struct listcmd *cmd;
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cmd = malloc(sizeof(*cmd));
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memset(cmd, 0, sizeof(*cmd));
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cmd->type = LIST;
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cmd->left = left;
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cmd->right = right;
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return (struct cmd*)cmd;
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}
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struct cmd*
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backcmd(struct cmd *subcmd)
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{
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struct backcmd *cmd;
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cmd = malloc(sizeof(*cmd));
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memset(cmd, 0, sizeof(*cmd));
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cmd->type = BACK;
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cmd->cmd = subcmd;
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return (struct cmd*)cmd;
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}
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// Parsing
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char whitespace[] = " \t\r\n\v";
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char symbols[] = "<|>&;()";
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int
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peek(char **ps, char *es, char *toks)
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{
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char *s;
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s = *ps;
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while(s < es && strchr(whitespace, *s))
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s++;
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*ps = s;
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return *s && strchr(toks, *s);
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}
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int
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ioredirection(struct ionode *iolist, int nio)
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gettoken(char **ps, char *es, char **q, char **eq)
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{
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int fd;
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struct ionode *io;
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char *s;
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int ret;
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s = *ps;
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while(s < es && strchr(whitespace, *s))
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s++;
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if(q)
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*q = s;
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ret = *s;
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switch(*s){
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case 0:
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break;
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case '|':
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case '(':
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case ')':
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case ';':
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case '&':
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case '<':
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s++;
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break;
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case '>':
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s++;
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if(*s == '>'){
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ret = '+';
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s++;
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}
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break;
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default:
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ret = 'a';
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while(s < es && !strchr(whitespace, *s) && !strchr(symbols, *s))
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s++;
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break;
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}
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if(eq)
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*eq = s;
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while(s < es && strchr(whitespace, *s))
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s++;
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*ps = s;
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return ret;
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}
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for(io = iolist; io < &iolist[nio]; io++) {
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switch(io->token) {
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void nulterminate(struct cmd*);
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struct cmd *parseline(char**, char*);
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struct cmd *parsepipe(char**, char*);
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struct cmd *parseredirs(struct cmd*, char**, char*);
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struct cmd *parseblock(char**, char*);
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struct cmd *parseexec(char**, char*);
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struct cmd*
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parsecmd(char *s)
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{
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char *es;
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struct cmd *cmd;
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es = s + strlen(s);
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cmd = parseline(&s, es);
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peek(&s, es, "");
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if(s != es){
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printf(2, "leftovers: %s\n", s);
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panic("syntax");
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}
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nulterminate(cmd);
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return cmd;
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}
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struct cmd*
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parseline(char **ps, char *es)
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{
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struct cmd *cmd;
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cmd = parsepipe(ps, es);
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while(peek(ps, es, "&")){
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gettoken(ps, es, 0, 0);
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cmd = backcmd(cmd);
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}
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if(peek(ps, es, ";")){
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gettoken(ps, es, 0, 0);
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cmd = listcmd(cmd, parseline(ps, es));
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}
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return cmd;
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}
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struct cmd*
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parsepipe(char **ps, char *es)
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{
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struct cmd *cmd;
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cmd = parseexec(ps, es);
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if(peek(ps, es, "|")){
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gettoken(ps, es, 0, 0);
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cmd = pipecmd(cmd, parsepipe(ps, es));
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}
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return cmd;
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}
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struct cmd*
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parseblock(char **ps, char *es)
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{
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struct cmd *cmd;
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if(!peek(ps, es, "("))
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panic("parseblock");
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gettoken(ps, es, 0, 0);
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cmd = parseline(ps, es);
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if(!peek(ps, es, ")"))
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panic("syntax - missing )");
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gettoken(ps, es, 0, 0);
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cmd = parseredirs(cmd, ps, es);
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return cmd;
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}
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struct cmd*
|
||||
parseredirs(struct cmd *cmd, char **ps, char *es)
|
||||
{
|
||||
int tok;
|
||||
char *q, *eq;
|
||||
|
||||
while(peek(ps, es, "<>")){
|
||||
tok = gettoken(ps, es, 0, 0);
|
||||
if(gettoken(ps, es, &q, &eq) != 'a')
|
||||
panic("missing file for redirection");
|
||||
switch(tok){
|
||||
case '<':
|
||||
if(close(0) < 0)
|
||||
printf(2, "close 0 failed\n");
|
||||
if((fd = open(io->s, O_RDONLY)) < 0) {
|
||||
printf(2, "failed to open %s for read: %d", io->s, fd);
|
||||
return -1;
|
||||
}
|
||||
if(debug)
|
||||
printf(2, "redirect 0 from %s\n", io->s);
|
||||
cmd = redircmd(cmd, q, eq, O_RDONLY, 0);
|
||||
break;
|
||||
case '>':
|
||||
if(close(1) < 0)
|
||||
printf(2, "close 1 failed\n");
|
||||
if((fd = open(io->s, O_WRONLY|O_CREATE)) < 0) {
|
||||
printf(2, "failed to open %s for write: %d", io->s, fd);
|
||||
exit();
|
||||
}
|
||||
if(debug)
|
||||
printf(2, "redirect 1 to %s\n", io->s);
|
||||
cmd = redircmd(cmd, q, eq, O_WRONLY|O_CREATE, 1);
|
||||
break;
|
||||
case '+': // >>
|
||||
cmd = redircmd(cmd, q, eq, O_WRONLY|O_CREATE, 1);
|
||||
break;
|
||||
}
|
||||
}
|
||||
return 0;
|
||||
return cmd;
|
||||
}
|
||||
|
||||
// gettoken(s, 0) prepares gettoken for subsequent calls and returns 0.
|
||||
// gettoken(0, token) parses a shell token from the previously set string,
|
||||
// null-terminates that token, stores the token pointer in '*token',
|
||||
// and returns a token ID (0, '<', '>', '|', or 'w').
|
||||
// Subsequent calls to 'gettoken(0, token)' will return subsequent
|
||||
// tokens from the string.
|
||||
|
||||
int
|
||||
gettoken(char *s, char **p1)
|
||||
struct cmd*
|
||||
parseexec(char **ps, char *es)
|
||||
{
|
||||
static int c, nc;
|
||||
static char *np1, *np2;
|
||||
char *q, *eq;
|
||||
int tok, argc;
|
||||
struct execcmd *cmd;
|
||||
struct cmd *ret;
|
||||
|
||||
if(peek(ps, es, "("))
|
||||
return parseblock(ps, es);
|
||||
|
||||
if(s) {
|
||||
nc = _gettoken(s, &np1, &np2);
|
||||
return 0;
|
||||
ret = execcmd();
|
||||
cmd = (struct execcmd*)ret;
|
||||
|
||||
argc = 0;
|
||||
ret = parseredirs(ret, ps, es);
|
||||
while(!peek(ps, es, "|)&;")){
|
||||
if((tok=gettoken(ps, es, &q, &eq)) == 0)
|
||||
break;
|
||||
if(tok != 'a')
|
||||
panic("syntax");
|
||||
cmd->argv[argc] = q;
|
||||
cmd->eargv[argc] = eq;
|
||||
argc++;
|
||||
if(argc >= MAXARGS)
|
||||
panic("too many args");
|
||||
ret = parseredirs(ret, ps, es);
|
||||
}
|
||||
c = nc;
|
||||
*p1 = np1;
|
||||
nc = _gettoken(np2, &np1, &np2);
|
||||
return c;
|
||||
cmd->argv[argc] = 0;
|
||||
cmd->eargv[argc] = 0;
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
||||
// Get the next token from string s.
|
||||
// Set *p1 to the beginning of the token and *p2 just past the token.
|
||||
// Returns
|
||||
// 0 for end-of-string;
|
||||
// < for <;
|
||||
// > for >;
|
||||
// | for |;
|
||||
// w for a word.
|
||||
//
|
||||
// Eventually (once we parse the space where the \0 will go),
|
||||
// words get nul-terminated.
|
||||
#define WHITESPACE " \t\r\n"
|
||||
#define SYMBOLS "<|>&;()"
|
||||
|
||||
int
|
||||
_gettoken(char *s, char **p1, char **p2)
|
||||
// NUL-terminate all the counted strings.
|
||||
void
|
||||
nulterminate(struct cmd *cmd)
|
||||
{
|
||||
int t;
|
||||
int i;
|
||||
struct backcmd *bcmd;
|
||||
struct execcmd *ecmd;
|
||||
struct listcmd *lcmd;
|
||||
struct pipecmd *pcmd;
|
||||
struct redircmd *rcmd;
|
||||
|
||||
if(s == 0) {
|
||||
if(debug > 1)
|
||||
printf(2, "GETTOKEN 0\n");
|
||||
return 0;
|
||||
}
|
||||
if(cmd == 0)
|
||||
return;
|
||||
|
||||
switch(cmd->type){
|
||||
case EXEC:
|
||||
ecmd = (struct execcmd*)cmd;
|
||||
for(i=0; ecmd->argv[i]; i++)
|
||||
*ecmd->eargv[i] = 0;
|
||||
break;
|
||||
|
||||
if(debug > 1)
|
||||
printf(2, "GETTOKEN: %s\n", s);
|
||||
case REDIR:
|
||||
rcmd = (struct redircmd*)cmd;
|
||||
nulterminate(rcmd->cmd);
|
||||
*rcmd->efile = 0;
|
||||
break;
|
||||
|
||||
*p1 = 0;
|
||||
*p2 = 0;
|
||||
case PIPE:
|
||||
pcmd = (struct pipecmd*)cmd;
|
||||
nulterminate(pcmd->left);
|
||||
nulterminate(pcmd->right);
|
||||
break;
|
||||
|
||||
case LIST:
|
||||
lcmd = (struct listcmd*)cmd;
|
||||
nulterminate(lcmd->left);
|
||||
nulterminate(lcmd->right);
|
||||
break;
|
||||
|
||||
while(strchr(WHITESPACE, *s))
|
||||
*s++ = 0;
|
||||
if(*s == 0) {
|
||||
if(debug > 1)
|
||||
printf(2, "EOL\n");
|
||||
return 0;
|
||||
case BACK:
|
||||
bcmd = (struct backcmd*)cmd;
|
||||
nulterminate(bcmd->cmd);
|
||||
break;
|
||||
}
|
||||
if(strchr(SYMBOLS, *s)) {
|
||||
t = *s;
|
||||
*p1 = s;
|
||||
*s++ = 0;
|
||||
*p2 = s;
|
||||
if(debug > 1)
|
||||
printf(2, "TOK %c\n", t);
|
||||
return t;
|
||||
}
|
||||
*p1 = s;
|
||||
while(*s && !strchr(WHITESPACE SYMBOLS, *s))
|
||||
s++;
|
||||
*p2 = s;
|
||||
if(debug > 1) {
|
||||
t = **p2;
|
||||
**p2 = 0;
|
||||
printf(2, "WORD: %s\n", *p1);
|
||||
**p2 = t;
|
||||
}
|
||||
return 'w';
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue