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Shell: Separate fd rewirings from redirections.

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This was unnecessarily confusing. When we build up a chain of commands
connected by pipes, we now store the file descriptors of each end of
these pipes as rewirings in a vector. The rewirings are then put into
effect by calls to dup2().
This commit is contained in:
Andreas Kling 2019-06-04 20:36:08 +02:00
parent 59dae9a766
commit 848044b74c
3 changed files with 19 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

2
Shell/Parser.cpp
View file

@ -19,7 +19,7 @@ void Parser::commit_subcommand()
{ {
if (m_tokens.is_empty()) if (m_tokens.is_empty())
return; return;
m_subcommands.append({ move(m_tokens), move(m_redirections) }); m_subcommands.append({ move(m_tokens), move(m_redirections), {} });
} }
void Parser::do_pipe() void Parser::do_pipe()

7
Shell/Parser.h
View file

@ -10,7 +10,6 @@ struct Redirection {
FileWrite, FileWrite,
FileWriteAppend, FileWriteAppend,
FileRead, FileRead,
Rewire
}; };
Type type; Type type;
int fd { -1 }; int fd { -1 };
@ -18,9 +17,15 @@ struct Redirection {
String path {}; String path {};
}; };
struct Rewiring {
int fd { -1 };
int rewire_fd { -1 };
};
struct Subcommand { struct Subcommand {
Vector<String> args; Vector<String> args;
Vector<Redirection> redirections; Vector<Redirection> redirections;
Vector<Rewiring> rewirings;
}; };
class Parser { class Parser {

20
Shell/main.cpp
View file

@ -315,9 +315,9 @@ static int run_command(const String& cmd)
perror("pipe"); perror("pipe");
return 1; return 1;
} }
subcommand.redirections.append({ Redirection::Rewire, STDOUT_FILENO, pipefd[1] }); subcommand.rewirings.append({ 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.rewirings.append({ STDIN_FILENO, pipefd[0] });
fds.add(pipefd[0]); fds.add(pipefd[0]);
fds.add(pipefd[1]); fds.add(pipefd[1]);
break; break;
@ -328,7 +328,7 @@ static int run_command(const String& cmd)
perror("open"); perror("open");
return 1; return 1;
} }
subcommand.redirections.append({ Redirection::Rewire, redirection.fd, fd }); subcommand.rewirings.append({ redirection.fd, fd });
fds.add(fd); fds.add(fd);
break; break;
} }
@ -338,7 +338,7 @@ static int run_command(const String& cmd)
perror("open"); perror("open");
return 1; return 1;
} }
subcommand.redirections.append({ Redirection::Rewire, redirection.fd, fd }); subcommand.rewirings.append({ redirection.fd, fd });
fds.add(fd); fds.add(fd);
break; break;
} }
@ -348,12 +348,10 @@ static int run_command(const String& cmd)
perror("open"); perror("open");
return 1; return 1;
} }
subcommand.redirections.append({ Redirection::Rewire, redirection.fd, fd }); subcommand.rewirings.append({ redirection.fd, fd });
fds.add(fd); fds.add(fd);
break; break;
} }
case Redirection::Rewire:
break; // ignore
} }
} }
} }
@ -390,18 +388,16 @@ static int run_command(const String& cmd)
if (!child) { if (!child) {
setpgid(0, 0); setpgid(0, 0);
tcsetpgrp(0, getpid()); tcsetpgrp(0, getpid());
for (auto& redirection : subcommand.redirections) { for (auto& rewiring : subcommand.rewirings) {
if (redirection.type == Redirection::Rewire) { #ifdef SH_DEBUG
#ifdef SH_DEBUGsh
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 #endif
int rc = dup2(redirection.rewire_fd, redirection.fd); int rc = dup2(rewiring.rewire_fd, rewiring.fd);
if (rc < 0) { if (rc < 0) {
perror("dup2"); perror("dup2");
return 1; return 1;
} }
} }
}
fds.collect(); fds.collect();