summaryrefslogtreecommitdiff
path: root/user/sh.c
diff options
context:
space:
mode:
Diffstat (limited to 'user/sh.c')
-rw-r--r--user/sh.c493
1 files changed, 493 insertions, 0 deletions
diff --git a/user/sh.c b/user/sh.c
new file mode 100644
index 0000000..13c7883
--- /dev/null
+++ b/user/sh.c
@@ -0,0 +1,493 @@
+// Shell.
+
+#include "kernel/types.h"
+#include "user/user.h"
+#include "kernel/fcntl.h"
+
+// Parsed command representation
+#define EXEC 1
+#define REDIR 2
+#define PIPE 3
+#define LIST 4
+#define BACK 5
+
+#define MAXARGS 10
+
+struct cmd {
+ int type;
+};
+
+struct execcmd {
+ int type;
+ char *argv[MAXARGS];
+ char *eargv[MAXARGS];
+};
+
+struct redircmd {
+ int type;
+ struct cmd *cmd;
+ char *file;
+ char *efile;
+ int mode;
+ int fd;
+};
+
+struct pipecmd {
+ int type;
+ struct cmd *left;
+ struct cmd *right;
+};
+
+struct listcmd {
+ int type;
+ struct cmd *left;
+ struct cmd *right;
+};
+
+struct backcmd {
+ int type;
+ struct cmd *cmd;
+};
+
+int fork1(void); // Fork but panics on failure.
+void panic(char*);
+struct cmd *parsecmd(char*);
+
+// Execute cmd. Never returns.
+void
+runcmd(struct cmd *cmd)
+{
+ int p[2];
+ struct backcmd *bcmd;
+ struct execcmd *ecmd;
+ struct listcmd *lcmd;
+ struct pipecmd *pcmd;
+ struct redircmd *rcmd;
+
+ if(cmd == 0)
+ exit();
+
+ switch(cmd->type){
+ default:
+ panic("runcmd");
+
+ case EXEC:
+ ecmd = (struct execcmd*)cmd;
+ if(ecmd->argv[0] == 0)
+ exit();
+ exec(ecmd->argv[0], ecmd->argv);
+ printf(2, "exec %s failed\n", ecmd->argv[0]);
+ break;
+
+ case REDIR:
+ rcmd = (struct redircmd*)cmd;
+ close(rcmd->fd);
+ if(open(rcmd->file, rcmd->mode) < 0){
+ printf(2, "open %s failed\n", rcmd->file);
+ exit();
+ }
+ runcmd(rcmd->cmd);
+ break;
+
+ case LIST:
+ lcmd = (struct listcmd*)cmd;
+ if(fork1() == 0)
+ runcmd(lcmd->left);
+ wait();
+ runcmd(lcmd->right);
+ break;
+
+ case PIPE:
+ pcmd = (struct pipecmd*)cmd;
+ if(pipe(p) < 0)
+ panic("pipe");
+ if(fork1() == 0){
+ close(1);
+ dup(p[1]);
+ close(p[0]);
+ close(p[1]);
+ runcmd(pcmd->left);
+ }
+ if(fork1() == 0){
+ close(0);
+ dup(p[0]);
+ close(p[0]);
+ close(p[1]);
+ runcmd(pcmd->right);
+ }
+ close(p[0]);
+ close(p[1]);
+ wait();
+ wait();
+ break;
+
+ case BACK:
+ bcmd = (struct backcmd*)cmd;
+ if(fork1() == 0)
+ runcmd(bcmd->cmd);
+ break;
+ }
+ exit();
+}
+
+int
+getcmd(char *buf, int nbuf)
+{
+ printf(2, "$ ");
+ memset(buf, 0, nbuf);
+ gets(buf, nbuf);
+ if(buf[0] == 0) // EOF
+ return -1;
+ return 0;
+}
+
+int
+main(void)
+{
+ static char buf[100];
+ int fd;
+
+ // Ensure that three file descriptors are open.
+ while((fd = open("console", O_RDWR)) >= 0){
+ if(fd >= 3){
+ close(fd);
+ break;
+ }
+ }
+
+ // Read and run input commands.
+ while(getcmd(buf, sizeof(buf)) >= 0){
+ if(buf[0] == 'c' && buf[1] == 'd' && buf[2] == ' '){
+ // Chdir must be called by the parent, not the child.
+ buf[strlen(buf)-1] = 0; // chop \n
+ if(chdir(buf+3) < 0)
+ printf(2, "cannot cd %s\n", buf+3);
+ continue;
+ }
+ if(fork1() == 0)
+ runcmd(parsecmd(buf));
+ wait();
+ }
+ exit();
+}
+
+void
+panic(char *s)
+{
+ printf(2, "%s\n", s);
+ exit();
+}
+
+int
+fork1(void)
+{
+ int pid;
+
+ pid = fork();
+ if(pid == -1)
+ panic("fork");
+ return pid;
+}
+
+//PAGEBREAK!
+// Constructors
+
+struct cmd*
+execcmd(void)
+{
+ struct execcmd *cmd;
+
+ cmd = malloc(sizeof(*cmd));
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->type = EXEC;
+ return (struct cmd*)cmd;
+}
+
+struct cmd*
+redircmd(struct cmd *subcmd, char *file, char *efile, int mode, int fd)
+{
+ struct redircmd *cmd;
+
+ cmd = malloc(sizeof(*cmd));
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->type = REDIR;
+ cmd->cmd = subcmd;
+ cmd->file = file;
+ cmd->efile = efile;
+ cmd->mode = mode;
+ cmd->fd = fd;
+ return (struct cmd*)cmd;
+}
+
+struct cmd*
+pipecmd(struct cmd *left, struct cmd *right)
+{
+ struct pipecmd *cmd;
+
+ cmd = malloc(sizeof(*cmd));
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->type = PIPE;
+ cmd->left = left;
+ cmd->right = right;
+ return (struct cmd*)cmd;
+}
+
+struct cmd*
+listcmd(struct cmd *left, struct cmd *right)
+{
+ struct listcmd *cmd;
+
+ cmd = malloc(sizeof(*cmd));
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->type = LIST;
+ cmd->left = left;
+ cmd->right = right;
+ return (struct cmd*)cmd;
+}
+
+struct cmd*
+backcmd(struct cmd *subcmd)
+{
+ struct backcmd *cmd;
+
+ cmd = malloc(sizeof(*cmd));
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->type = BACK;
+ cmd->cmd = subcmd;
+ return (struct cmd*)cmd;
+}
+//PAGEBREAK!
+// Parsing
+
+char whitespace[] = " \t\r\n\v";
+char symbols[] = "<|>&;()";
+
+int
+gettoken(char **ps, char *es, char **q, char **eq)
+{
+ char *s;
+ int ret;
+
+ s = *ps;
+ while(s < es && strchr(whitespace, *s))
+ s++;
+ if(q)
+ *q = s;
+ ret = *s;
+ switch(*s){
+ case 0:
+ break;
+ case '|':
+ case '(':
+ case ')':
+ case ';':
+ case '&':
+ case '<':
+ s++;
+ break;
+ case '>':
+ s++;
+ if(*s == '>'){
+ ret = '+';
+ s++;
+ }
+ break;
+ default:
+ ret = 'a';
+ while(s < es && !strchr(whitespace, *s) && !strchr(symbols, *s))
+ s++;
+ break;
+ }
+ if(eq)
+ *eq = s;
+
+ while(s < es && strchr(whitespace, *s))
+ s++;
+ *ps = s;
+ return ret;
+}
+
+int
+peek(char **ps, char *es, char *toks)
+{
+ char *s;
+
+ s = *ps;
+ while(s < es && strchr(whitespace, *s))
+ s++;
+ *ps = s;
+ return *s && strchr(toks, *s);
+}
+
+struct cmd *parseline(char**, char*);
+struct cmd *parsepipe(char**, char*);
+struct cmd *parseexec(char**, char*);
+struct cmd *nulterminate(struct cmd*);
+
+struct cmd*
+parsecmd(char *s)
+{
+ char *es;
+ struct cmd *cmd;
+
+ es = s + strlen(s);
+ cmd = parseline(&s, es);
+ peek(&s, es, "");
+ if(s != es){
+ printf(2, "leftovers: %s\n", s);
+ panic("syntax");
+ }
+ nulterminate(cmd);
+ return cmd;
+}
+
+struct cmd*
+parseline(char **ps, char *es)
+{
+ struct cmd *cmd;
+
+ cmd = parsepipe(ps, es);
+ while(peek(ps, es, "&")){
+ gettoken(ps, es, 0, 0);
+ cmd = backcmd(cmd);
+ }
+ if(peek(ps, es, ";")){
+ gettoken(ps, es, 0, 0);
+ cmd = listcmd(cmd, parseline(ps, es));
+ }
+ return cmd;
+}
+
+struct cmd*
+parsepipe(char **ps, char *es)
+{
+ struct cmd *cmd;
+
+ cmd = parseexec(ps, es);
+ if(peek(ps, es, "|")){
+ gettoken(ps, es, 0, 0);
+ cmd = pipecmd(cmd, parsepipe(ps, es));
+ }
+ return cmd;
+}
+
+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 '<':
+ cmd = redircmd(cmd, q, eq, O_RDONLY, 0);
+ break;
+ case '>':
+ cmd = redircmd(cmd, q, eq, O_WRONLY|O_CREATE, 1);
+ break;
+ case '+': // >>
+ cmd = redircmd(cmd, q, eq, O_WRONLY|O_CREATE, 1);
+ break;
+ }
+ }
+ return cmd;
+}
+
+struct cmd*
+parseblock(char **ps, char *es)
+{
+ struct cmd *cmd;
+
+ if(!peek(ps, es, "("))
+ panic("parseblock");
+ gettoken(ps, es, 0, 0);
+ cmd = parseline(ps, es);
+ if(!peek(ps, es, ")"))
+ panic("syntax - missing )");
+ gettoken(ps, es, 0, 0);
+ cmd = parseredirs(cmd, ps, es);
+ return cmd;
+}
+
+struct cmd*
+parseexec(char **ps, char *es)
+{
+ char *q, *eq;
+ int tok, argc;
+ struct execcmd *cmd;
+ struct cmd *ret;
+
+ if(peek(ps, es, "("))
+ return parseblock(ps, es);
+
+ 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);
+ }
+ cmd->argv[argc] = 0;
+ cmd->eargv[argc] = 0;
+ return ret;
+}
+
+// NUL-terminate all the counted strings.
+struct cmd*
+nulterminate(struct cmd *cmd)
+{
+ int i;
+ struct backcmd *bcmd;
+ struct execcmd *ecmd;
+ struct listcmd *lcmd;
+ struct pipecmd *pcmd;
+ struct redircmd *rcmd;
+
+ if(cmd == 0)
+ return 0;
+
+ switch(cmd->type){
+ case EXEC:
+ ecmd = (struct execcmd*)cmd;
+ for(i=0; ecmd->argv[i]; i++)
+ *ecmd->eargv[i] = 0;
+ break;
+
+ case REDIR:
+ rcmd = (struct redircmd*)cmd;
+ nulterminate(rcmd->cmd);
+ *rcmd->efile = 0;
+ break;
+
+ 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;
+
+ case BACK:
+ bcmd = (struct backcmd*)cmd;
+ nulterminate(bcmd->cmd);
+ break;
+ }
+ return cmd;
+}
Powered by cgit, Theme cgit-dark created by Ted Yin, updated by Mole Shang.