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sh: Add basic command piping support.
This commit is contained in:
Andreas Kling
parent
aa84e2fc64
commit
07de1147ad
Notes:
sideshowbarker
2024-07-19 14:35:44 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/07de1147ad6
241
Userland/sh.cpp
241
Userland/sh.cpp
@ -143,6 +143,122 @@ static int try_exec(const char* path, char** argv)
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return ret;
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}
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struct Redirection {
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enum Type { Pipe, File, Rewire };
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Type type;
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int fd;
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int rewire_fd;
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};
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struct Subcommand {
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Vector<String> args;
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Vector<Redirection> redirections;
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};
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enum class ParseState {
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Free,
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InSingleQuotes,
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InDoubleQuotes,
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};
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static Vector<Subcommand> parse(const char* command)
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{
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ParseState state = ParseState::Free;
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Vector<Subcommand> subcommands;
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Vector<String> current_command;
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Vector<char> current_token;
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auto commit_token = [&] {
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if (current_token.is_empty())
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return;
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current_command.append(String::copy(current_token));
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current_token.clear_with_capacity();
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};
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auto commit_subcommand = [&] {
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if (current_command.is_empty())
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return;
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subcommands.append({ current_command });
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current_command.clear();
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};
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auto begin_pipe = [&] {
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Vector<Redirection> redirections;
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redirections.append({ Redirection::Pipe, STDOUT_FILENO });
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subcommands.append({ current_command, move(redirections) });
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current_command.clear();
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};
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for (const char* c = command; *c; ++c) {
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switch (state) {
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case ParseState::Free:
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if (*c == ' ') {
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commit_token();
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break;
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}
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if (*c == '|') {
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commit_token();
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if (current_command.is_empty()) {
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fprintf(stderr, "Syntax error: Nothing before pipe (|)\n");
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return { };
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}
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begin_pipe();
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break;
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}
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#if 0
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if (*c == '>') {
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begin_redirect(STDOUT_FILENO);
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break;
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}
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if (*c == '<') {
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begin_redirect(STDIN_FILENO);
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break;
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}
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#endif
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if (*c == '\'') {
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state = ParseState::InSingleQuotes;
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break;
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}
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if (*c == '\"') {
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state = ParseState::InDoubleQuotes;
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break;
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}
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current_token.append(*c);
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break;
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case ParseState::InSingleQuotes:
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if (*c == '\'') {
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commit_token();
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state = ParseState::Free;
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break;
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}
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current_token.append(*c);
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break;
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case ParseState::InDoubleQuotes:
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if (*c == '\"') {
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commit_token();
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state = ParseState::Free;
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break;
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}
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current_token.append(*c);
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break;
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};
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}
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commit_token();
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commit_subcommand();
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if (!subcommands.is_empty()) {
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for (auto& redirection : subcommands.last().redirections) {
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if (redirection.type == Redirection::Pipe) {
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fprintf(stderr, "Syntax error: Nothing after last pipe (|)\n");
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return { };
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}
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}
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}
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return subcommands;
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}
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static int runcmd(char* cmd)
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{
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if (cmd[0] == 0)
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@ -150,48 +266,109 @@ static int runcmd(char* cmd)
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char buf[128];
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memcpy(buf, cmd, 128);
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char* argv[32];
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size_t argc = 1;
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argv[0] = &buf[0];
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size_t buflen = strlen(buf);
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for (size_t i = 0; i < buflen; ++i) {
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if (buf[i] == ' ') {
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buf[i] = '\0';
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argv[argc++] = &buf[i + 1];
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}
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}
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argv[argc] = nullptr;
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auto subcommands = parse(cmd);
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int retval = 0;
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if (handle_builtin(argc, argv, retval)) {
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#ifdef PARSE_DEBUG
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for (int i = 0; i < subcommands.size(); ++i) {
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for (int j = 0; j < i; ++j)
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printf(" ");
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for (auto& arg : subcommands[i].args) {
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printf("<%s> ", arg.characters());
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}
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printf("\n");
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}
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#endif
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if (subcommands.is_empty())
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return 0;
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Vector<int> fds;
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for (int i = 0; i < subcommands.size(); ++i) {
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auto& subcommand = subcommands[i];
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for (auto& redirection : subcommand.redirections) {
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if (redirection.type == Redirection::Pipe) {
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int pipefd[2];
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int rc = pipe(pipefd);
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if (rc < 0) {
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perror("pipe");
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return 1;
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}
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subcommand.redirections.append({ Redirection::Rewire, STDOUT_FILENO, pipefd[1] });
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auto& next_command = subcommands[i + 1];
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next_command.redirections.append({ Redirection::Rewire, STDIN_FILENO, pipefd[0] });
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fds.append(pipefd[0]);
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fds.append(pipefd[1]);
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}
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}
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}
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struct termios trm;
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tcgetattr(0, &trm);
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pid_t child = fork();
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if (!child) {
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setpgid(0, 0);
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tcsetpgrp(0, getpid());
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int ret = try_exec(argv[0], argv);
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if (ret < 0) {
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printf("exec failed: %s (%s)\n", cmd, strerror(errno));
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exit(1);
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Vector<pid_t> children;
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for (int i = 0; i < subcommands.size(); ++i) {
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auto& subcommand = subcommands[i];
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Vector<const char*> argv;
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for (auto& arg : subcommand.args)
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argv.append(arg.characters());
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argv.append(nullptr);
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int retval = 0;
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if (handle_builtin(argv.size() - 1, (char**)argv.data(), retval))
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return retval;
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pid_t child = fork();
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if (!child) {
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setpgid(0, 0);
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tcsetpgrp(0, getpid());
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for (auto& redirection : subcommand.redirections) {
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if (redirection.type == Redirection::Rewire) {
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dbgprintf("in %s<%d>, dup2(%d, %d)\n", argv[0], getpid(), redirection.rewire_fd, redirection.fd);
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int rc = dup2(redirection.rewire_fd, redirection.fd);
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if (rc < 0) {
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perror("dup2");
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return 1;
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}
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}
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}
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for (auto& fd : fds)
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close(fd);
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int rc = execvp(argv[0], (char* const*)argv.data());
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if (rc < 0) {
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perror("execvp");
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exit(1);
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}
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ASSERT_NOT_REACHED();
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}
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// We should never get here!
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ASSERT_NOT_REACHED();
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children.append(child);
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}
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dbgprintf("Closing fds in shell process:\n");
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for (auto& fd : fds) {
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dbgprintf(" %d\n", fd);
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close(fd);
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}
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dbgprintf("Now we gotta wait on children:\n");
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for (auto& child : children)
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dbgprintf(" %d\n", child);
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int wstatus = 0;
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int rc;
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do {
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rc = waitpid(child, &wstatus, 0);
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if (rc < 0 && errno != EINTR) {
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perror("waitpid");
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break;
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}
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} while(errno == EINTR);
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for (auto& child : children) {
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do {
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rc = waitpid(child, &wstatus, 0);
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if (rc < 0 && errno != EINTR) {
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perror("waitpid");
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break;
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}
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} while(errno == EINTR);
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}
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// FIXME: Should I really have to tcsetpgrp() after my child has exited?
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// Is the terminal controlling pgrp really still the PGID of the dead process?
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@ -202,6 +379,7 @@ static int runcmd(char* cmd)
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if (WIFEXITED(wstatus)) {
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if (WEXITSTATUS(wstatus) != 0)
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printf("Exited with status %d\n", WEXITSTATUS(wstatus));
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return WEXITSTATUS(wstatus);
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} else {
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if (WIFSIGNALED(wstatus)) {
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switch (WTERMSIG(wstatus)) {
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@ -214,9 +392,10 @@ static int runcmd(char* cmd)
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}
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} else {
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printf("Exited abnormally\n");
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return 1;
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}
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}
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return retval;
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return 0;
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}
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int main(int argc, char** argv)
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