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sh: Add support for redirecting stdin and stdout with < and >.

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This is certainly about time. The kernel has had all the necessary support
in place for months, and I just kept postponing working on the shell. :^)
This commit is contained in:
Andreas Kling 2019-04-25 16:10:16 +02:00
parent df8e76a67c
commit 04b7def6ab
1 changed files with 112 additions and 20 deletions
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132
Userland/sh.cpp
View file

@ -12,6 +12,8 @@
#include <sys/utsname.h> #include <sys/utsname.h>
#include <AK/FileSystemPath.h> #include <AK/FileSystemPath.h>
//#define SH_DEBUG
struct GlobalState { struct GlobalState {
String cwd; String cwd;
String username; String username;
@ -120,10 +122,11 @@ static bool handle_builtin(int argc, char** argv, int& retval)
} }
struct Redirection { struct Redirection {
enum Type { Pipe, File, Rewire }; enum Type { Pipe, FileWrite, FileRead, Rewire };
Type type; Type type;
int fd { -1 }; int fd { -1 };
int rewire_fd { -1 }; int rewire_fd { -1 };
String path { };
}; };
struct Subcommand { struct Subcommand {
@ -141,7 +144,8 @@ private:
void commit_token(); void commit_token();
void commit_subcommand(); void commit_subcommand();
void do_pipe(); void do_pipe();
void begin_redirect_fd(int fd); void begin_redirect_read(int fd);
void begin_redirect_write(int fd);
enum State { enum State {
Free, Free,
@ -162,6 +166,11 @@ void Parser::commit_token()
{ {
if (m_token.is_empty()) if (m_token.is_empty())
return; return;
if (m_state == InRedirectionPath) {
m_redirections.last().path = String::copy(m_token);
m_token.clear_with_capacity();
return;
}
m_tokens.append(String::copy(m_token)); m_tokens.append(String::copy(m_token));
m_token.clear_with_capacity(); m_token.clear_with_capacity();
}; };
@ -179,9 +188,14 @@ void Parser::do_pipe()
commit_subcommand(); commit_subcommand();
} }
void Parser::begin_redirect_fd(int fd) void Parser::begin_redirect_read(int fd)
{ {
m_redirections.append({ Redirection::File, fd }); m_redirections.append({ Redirection::FileRead, fd });
}
void Parser::begin_redirect_write(int fd)
{
m_redirections.append({ Redirection::FileWrite, fd });
} }
Vector<Subcommand> Parser::parse() Vector<Subcommand> Parser::parse()
@ -204,12 +218,14 @@ Vector<Subcommand> Parser::parse()
break; break;
} }
if (ch == '>') { if (ch == '>') {
begin_redirect_fd(STDOUT_FILENO); commit_token();
begin_redirect_write(STDOUT_FILENO);
m_state = State::InRedirectionPath; m_state = State::InRedirectionPath;
break; break;
} }
if (ch == '<') { if (ch == '<') {
begin_redirect_fd(STDIN_FILENO); commit_token();
begin_redirect_read(STDIN_FILENO);
m_state = State::InRedirectionPath; m_state = State::InRedirectionPath;
break; break;
} }
@ -224,10 +240,31 @@ Vector<Subcommand> Parser::parse()
m_token.append(ch); m_token.append(ch);
break; break;
case State::InRedirectionPath: case State::InRedirectionPath:
if (ch == ' ') { if (ch == '<') {
commit_token(); commit_token();
begin_redirect_read(STDIN_FILENO);
m_state = State::InRedirectionPath;
break; break;
} }
if (ch == '>') {
commit_token();
begin_redirect_read(STDOUT_FILENO);
m_state = State::InRedirectionPath;
break;
}
if (ch == '|') {
commit_token();
if (m_tokens.is_empty()) {
fprintf(stderr, "Syntax error: Nothing before pipe (|)\n");
return { };
}
do_pipe();
m_state = State::Free;
break;
}
if (ch == ' ')
break;
m_token.append(ch);
break; break;
case State::InSingleQuotes: case State::InSingleQuotes:
if (ch == '\'') { if (ch == '\'') {
@ -262,6 +299,23 @@ Vector<Subcommand> Parser::parse()
return move(m_subcommands); return move(m_subcommands);
} }
class FileDescriptorCollector {
public:
FileDescriptorCollector() { }
~FileDescriptorCollector() { collect(); }
void collect()
{
for (auto fd : m_fds)
close(fd);
m_fds.clear();
}
void add(int fd) { m_fds.append(fd); }
private:
Vector<int, 32> m_fds;
};
static int runcmd(char* cmd) static int runcmd(char* cmd)
{ {
if (cmd[0] == 0) if (cmd[0] == 0)
@ -271,21 +325,39 @@ static int runcmd(char* cmd)
auto subcommands = Parser(cmd).parse(); auto subcommands = Parser(cmd).parse();
#ifdef PARSE_DEBUG #ifdef SH_DEBUG
for (int i = 0; i < subcommands.size(); ++i) { for (int i = 0; i < subcommands.size(); ++i) {
for (int j = 0; j < i; ++j) for (int j = 0; j < i; ++j)
printf(" "); printf(" ");
for (auto& arg : subcommands[i].args) { for (auto& arg : subcommands[i].args) {
printf("<%s> ", arg.characters()); printf("<%s> ", arg.characters());
} }
printf("\n"); printf("\n");
for (auto& redirecton : subcommands[i].redirections) {
for (int j = 0; j < i; ++j)
printf(" ");
printf(" ");
switch (redirecton.type) {
case Redirection::Pipe:
printf("Pipe\n");
break;
case Redirection::FileRead:
printf("fd:%d = FileRead: %s\n", redirecton.fd, redirecton.path.characters());
break;
case Redirection::FileWrite:
printf("fd:%d = FileWrite: %s\n", redirecton.fd, redirecton.path.characters());
break;
default:
break;
}
}
} }
#endif #endif
if (subcommands.is_empty()) if (subcommands.is_empty())
return 0; return 0;
Vector<int> fds; FileDescriptorCollector fds;
for (int i = 0; i < subcommands.size(); ++i) { for (int i = 0; i < subcommands.size(); ++i) {
auto& subcommand = subcommands[i]; auto& subcommand = subcommands[i];
@ -300,8 +372,26 @@ static int runcmd(char* cmd)
subcommand.redirections.append({ Redirection::Rewire, STDOUT_FILENO, pipefd[1] }); subcommand.redirections.append({ Redirection::Rewire, STDOUT_FILENO, pipefd[1] });
auto& next_command = subcommands[i + 1]; auto& next_command = subcommands[i + 1];
next_command.redirections.append({ Redirection::Rewire, STDIN_FILENO, pipefd[0] }); next_command.redirections.append({ Redirection::Rewire, STDIN_FILENO, pipefd[0] });
fds.append(pipefd[0]); fds.add(pipefd[0]);
fds.append(pipefd[1]); fds.add(pipefd[1]);
}
if (redirection.type == Redirection::FileWrite) {
int fd = open(redirection.path.characters(), O_WRONLY | O_CREAT, 0666);
if (fd < 0) {
perror("open");
return 1;
}
subcommand.redirections.append({ Redirection::Rewire, redirection.fd, fd });
fds.add(fd);
}
if (redirection.type == Redirection::FileRead) {
int fd = open(redirection.path.characters(), O_RDONLY);
if (fd < 0) {
perror("open");
return 1;
}
subcommand.redirections.append({ Redirection::Rewire, redirection.fd, fd });
fds.add(fd);
} }
} }
} }
@ -319,7 +409,7 @@ static int runcmd(char* cmd)
argv.append(nullptr); argv.append(nullptr);
int retval = 0; int retval = 0;
if (handle_builtin(argv.size() - 1, (char**)argv.data(), retval)) if (handle_builtin(argv.size() - 1, const_cast<char**>(argv.data()), retval))
return retval; return retval;
pid_t child = fork(); pid_t child = fork();
@ -328,7 +418,9 @@ static int runcmd(char* cmd)
tcsetpgrp(0, getpid()); tcsetpgrp(0, getpid());
for (auto& redirection : subcommand.redirections) { for (auto& redirection : subcommand.redirections) {
if (redirection.type == Redirection::Rewire) { if (redirection.type == Redirection::Rewire) {
#ifdef SH_DEBUG
dbgprintf("in %s<%d>, dup2(%d, %d)\n", argv[0], getpid(), redirection.rewire_fd, redirection.fd); dbgprintf("in %s<%d>, dup2(%d, %d)\n", argv[0], getpid(), redirection.rewire_fd, redirection.fd);
#endif
int rc = dup2(redirection.rewire_fd, redirection.fd); int rc = dup2(redirection.rewire_fd, redirection.fd);
if (rc < 0) { if (rc < 0) {
perror("dup2"); perror("dup2");
@ -337,10 +429,9 @@ static int runcmd(char* cmd)
} }
} }
for (auto& fd : fds) fds.collect();
close(fd);
int rc = execvp(argv[0], (char* const*)argv.data()); int rc = execvp(argv[0], const_cast<char* const*>(argv.data()));
if (rc < 0) { if (rc < 0) {
perror("execvp"); perror("execvp");
exit(1); exit(1);
@ -350,13 +441,14 @@ static int runcmd(char* cmd)
children.append(child); children.append(child);
} }
#ifdef SH_DEBUG
dbgprintf("Closing fds in shell process:\n"); dbgprintf("Closing fds in shell process:\n");
for (auto& fd : fds) { #endif
dbgprintf(" %d\n", fd); fds.collect();
close(fd);
}
#ifdef SH_DEBUG
dbgprintf("Now we gotta wait on children:\n"); dbgprintf("Now we gotta wait on children:\n");
#endif
for (auto& child : children) for (auto& child : children)
dbgprintf(" %d\n", child); dbgprintf(" %d\n", child);