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get precedence of <, >, and | right
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simplify
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kaashoek committed Sep 7, 2006
1 parent 1133b21 commit e00baa9
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Showing 2 changed files with 52 additions and 60 deletions.
2 changes: 1 addition & 1 deletion main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ main0(void)
// enable interrupts on the local APIC
lapic_enableintr();

// Enable interrupts on this processor.
// enable interrupts on this processor.
cpus[cpu()].nlock--;
sti();

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110 changes: 51 additions & 59 deletions sh.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,27 +16,26 @@ struct ionode {
int token;
char *s;
};
struct ionode iolist[MAXNODE];
int nextio;

struct cmd {
char *argv[MAXARGS];
char argv0buf[BUFSIZ];
int argc;
int token;
struct ionode iolist[MAXNODE];
struct ionode *io;
};
struct cmd cmdlist[MAXCMD];
int nextcmd;
struct cmd *cmd;

char buf[BUFSIZ];
int debug = 0;

int parse(char *s);
void runcmd(void);
int ioredirection(void);
int ioredirection(struct ionode *iolist, int nio);
int gettoken(char *s, char **token);
int _gettoken(char *s, char **p1, char **p2);
void addio(int token, char *s);

int
main(void)
Expand All @@ -59,21 +58,21 @@ parse(char *s)

gettoken(s, 0);

nextio = 0;
nextcmd = 0;
cmd = &cmdlist[0];;
for(i = 0; i < MAXCMD; i++) {
cmdlist[i].argc = 0;
cmdlist[i].token = 0;
cmdlist[i].io = cmdlist[i].iolist;
}
while(1) {
switch((c = gettoken(0, &t))) {

case 'w': // Add an argument
if(cmdlist[nextcmd].argc >= MAXARGS) {
if(cmd->argc >= MAXARGS) {
printf(2, "too many arguments\n");
return -1;
}
cmdlist[nextcmd].argv[cmdlist[nextcmd].argc++] = t;
cmd->argv[cmd->argc++] = t;
break;

case '<': // Input redirection
Expand All @@ -82,7 +81,9 @@ parse(char *s)
printf(2, "syntax error: < not followed by word\n");
return -1;
}
addio('<', t);
cmd->io->token = '<';
cmd->io->s = t;
cmd->io++;
break;

case '>': // Output redirection
Expand All @@ -91,13 +92,15 @@ parse(char *s)
printf(2, "syntax error: > not followed by word\n");
return -1;
}
addio('>', t);
cmd->io->token = '>';
cmd->io->s = t;
cmd->io++;
break;

case ';': // command sequence
case '|': // pipe
cmdlist[nextcmd].token = c;
nextcmd++;
cmd->token = c;
cmd++;
break;

case 0: // String is complete
Expand All @@ -115,8 +118,10 @@ parse(char *s)
void
runcmd(void)
{
int c, i, r, pid, tfd;
int i, r, pid, tfd;
int fdarray[2];
struct cmd *c;
struct ionode *io;

// Return immediately if command line was empty.
if(cmdlist[0].argc == 0) {
Expand All @@ -125,43 +130,43 @@ runcmd(void)
return;
}

for(c = 0; c <= nextcmd; c++) {
for(c = &cmdlist[0]; c <= cmd; c++) {
// Clean up command line.
// Read all commands from the filesystem: add an initial '/' to
// the command name.
// This essentially acts like 'PATH=/'.
if(cmdlist[c].argv[0][0] != '/') {
cmdlist[c].argv0buf[0] = '/';
strcpy(cmdlist[c].argv0buf + 1, cmdlist[c].argv[0]);
cmdlist[c].argv[0] = cmdlist[c].argv0buf;
if(c->argv[0][0] != '/') {
c->argv0buf[0] = '/';
strcpy(c->argv0buf + 1, c->argv[0]);
c->argv[0] = c->argv0buf;
}
cmdlist[c].argv[cmdlist[c].argc] = 0;
c->argv[c->argc] = 0;

// Print the command.
if(debug) {
printf(2, "[%d] SPAWN:", getpid());
for(i = 0; cmdlist[c].argv[i]; i++)
printf(2, " %s", cmdlist[c].argv[i]);
for(i = 0; i < nextio; i++) {
printf(2, "%c %s", iolist[i].token, iolist[i].s);
for(i = 0; c->argv[i]; i++)
printf(2, " %s", c->argv[i]);
for(io = c->iolist; io <= c->io; io++) {
printf(2, "%c %s", io->token, io->s);
}
printf(2, "\n");
}

if(strcmp(cmdlist[c].argv[0], "/cd") == 0) {
if(strcmp(c->argv[0], "/cd") == 0) {
if(debug)
printf (2, "/cd %s is build in\n", cmdlist[c].argv[1]);
chdir(cmdlist[c].argv[1]);
printf (2, "/cd %s is build in\n", c->argv[1]);
chdir(c->argv[1]);
return;
}

if(cmdlist[c].token == '|')
if(c->token == '|')
if(pipe(fdarray) < 0)
printf(2, "cmd %d pipe failed\n", c);

pid = fork();
if(pid == 0) {
if(cmdlist[c].token == '|') {
if(c->token == '|') {
if(close(1) < 0)
printf(2, "close 1 failed\n");
if((tfd = dup(fdarray[1])) < 0)
Expand All @@ -171,7 +176,7 @@ runcmd(void)
if(close(fdarray[1]) < 0)
printf(2, "close fdarray[1] failed\n");
}
if(c > 0 && cmdlist[c-1].token == '|') {
if(c > cmdlist && (c-1)->token == '|') {
if(close(0) < 0)
printf(2, "close 0 failed\n");
if((tfd = dup(fdarray[0])) < 0)
Expand All @@ -181,22 +186,22 @@ runcmd(void)
if(close(fdarray[1]) < 0)
printf(2, "close fdarray[1] failed\n");
}
if(ioredirection() < 0)
if(ioredirection(c->iolist, c->io - c->iolist) < 0)
exit();
if((r = exec(cmdlist[c].argv0buf, (char**) cmdlist[c].argv)) < 0) {
printf(2, "exec %s: %d\n", cmdlist[c].argv[0], r);
if((r = exec(c->argv0buf, (char**) c->argv)) < 0) {
printf(2, "exec %s: %d\n", c->argv[0], r);
exit();
}
} else if(pid > 0) {
int p;
if(debug)
printf(2, "[%d] FORKED child %d\n", getpid(), pid);

if(c > 0 && cmdlist[c-1].token == '|') {
if(c > cmdlist && (c-1)->token == '|') {
close(fdarray[0]);
close(fdarray[1]);
}
if(cmdlist[c].token != '|') {
if(c->token != '|') {
if(debug)
printf(2, "[%d] WAIT for children\n", getpid());
do {
Expand All @@ -212,51 +217,38 @@ runcmd(void)
}

int
ioredirection(void)
ioredirection(struct ionode *iolist, int nio)
{
int i, fd;
int fd;
struct ionode *io;

for(i = 0; i < nextio; i++) {
switch(iolist[i].token) {
for(io = iolist; io < &iolist[nio]; io++) {
switch(io->token) {
case '<':
if(close(0) < 0)
printf(2, "close 0 failed\n");
if((fd = open(iolist[i].s, O_RDONLY)) < 0) {
printf(2, "failed to open %s for read: %d", iolist[i].s, fd);
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", iolist[i].s);
printf(2, "redirect 0 from %s\n", io->s);
break;
case '>':
if(close(1) < 0)
printf(2, "close 1 failed\n");
if((fd = open(iolist[i].s, O_WRONLY|O_CREATE)) < 0) {
printf(2, "failed to open %s for write: %d", iolist[i].s, fd);
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", iolist[i].s);
printf(2, "redirect 1 to %s\n", io->s);
break;
}
}
return 0;
}

void
addio(int token, char *s)
{
if(nextio >= MAXNODE) {
printf(2, "addio: ran out of nodes\n");
return;
}

iolist[nextio].token = token;
iolist[nextio].s = s;
nextio++;
}


// 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',
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