diff options
Diffstat (limited to 'src/user/sh.cc')
| -rw-r--r-- | src/user/sh.cc | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/src/user/sh.cc b/src/user/sh.cc new file mode 100644 index 0000000..287d2be --- /dev/null +++ b/src/user/sh.cc @@ -0,0 +1,409 @@ +#include "ulib/stdio.h" +#include "ulib/stdlib.h" +#include "ulib/string.h" +#include "user/user.h" +#include "common/fcntl.h" + +constexpr int MAX_ARGS = 10; +const char *WHITESPACE = " \t\r\n\v"; +const char *SYMBOLS = "<|>&;()"; + +void panic(const char *s) +{ + printf("shell panic: %s\n", s); + exit(1); +} + +int fork_or_panic() +{ + int pid = fork(); + if (pid == -1) + panic("fork"); + return pid; +} + +struct Command +{ + virtual ~Command() = default; + + virtual void run() = 0; +}; + +struct ExecCommand : public Command +{ + char *argv[MAX_ARGS]; + + ExecCommand() + { + memset(argv, 0, sizeof(argv)); + } + + void run() override + { + if (argv[0] == nullptr) + exit(1); + + exec(argv[0], argv); + + printf("exec %s failed\n", argv[0]); + exit(1); + } +}; + +struct RedirCommand : public Command +{ + Command *sub_cmd; + char *file; + char *efile; // file name end pointer (used by parser) + int mode; + int fd; + + RedirCommand(Command *c, char *f, char *ef, int m, int fd_in) + : sub_cmd(c), file(f), efile(ef), mode(m), fd(fd_in) {} + + ~RedirCommand() { delete sub_cmd; } + + void run() override + { + close(fd); + if (open(file, mode) < 0) + { + printf("open %s failed\n", file); + exit(1); + } + sub_cmd->run(); + } +}; + +struct PipeCommand : public Command +{ + Command *left; + Command *right; + + PipeCommand(Command *l, Command *r) : left(l), right(r) {} + ~PipeCommand() + { + delete left; + delete right; + } + + void run() override + { + int p[2]; + if (pipe(p) < 0) + panic("pipe"); + + if (fork_or_panic() == 0) + { + // Left child: write to pipe + close(1); // close stdout + dup(p[1]); // dup write-end to stdout + close(p[0]); + close(p[1]); + left->run(); + } + + if (fork_or_panic() == 0) + { + // Right child: read from pipe + close(0); // close stdin + dup(p[0]); // dup read-end to stdin + close(p[0]); + close(p[1]); + right->run(); + } + + close(p[0]); + close(p[1]); + wait(0); + wait(0); + exit(0); + } +}; + +struct ListCommand : public Command +{ + Command *left; + Command *right; + + ListCommand(Command *l, Command *r) : left(l), right(r) {} + ~ListCommand() + { + delete left; + delete right; + } + + void run() override + { + if (fork_or_panic() == 0) + { + left->run(); + } + wait(0); + right->run(); + } +}; + +struct BackCommand : public Command +{ + Command *sub_cmd; + + BackCommand(Command *c) : sub_cmd(c) {} + ~BackCommand() { delete sub_cmd; } + + void run() override + { + if (fork_or_panic() == 0) + { + sub_cmd->run(); + } + // Parent doesn't wait + exit(0); + } +}; + +class Parser +{ +public: + static Command *parse(char *s) + { + char *es = s + strlen(s); + Command *cmd = parse_line(&s, es); + peek(&s, es, ""); + if (s != es) + { + printf("leftovers: %s\n", s); + // panic("syntax"); // strict syntax check + } + terminate_strings(cmd); + return cmd; + } + +private: + // Helper: NUL-terminate strings found during parsing + static void terminate_strings(Command *cmd) + { + if (!cmd) + return; + } + + static char get_token(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; + } + + static int peek(char **ps, char *es, const char *toks) + { + char *s = *ps; + while (s < es && strchr(WHITESPACE, *s)) + s++; + *ps = s; + return *s && strchr(toks, *s); + } + + // Recursive Descent Parsers + + static Command *parse_line(char **ps, char *es) + { + Command *cmd = parse_pipe(ps, es); + while (peek(ps, es, "&")) + { + get_token(ps, es, 0, 0); + cmd = new BackCommand(cmd); + } + if (peek(ps, es, ";")) + { + get_token(ps, es, 0, 0); + cmd = new ListCommand(cmd, parse_line(ps, es)); + } + return cmd; + } + + static Command *parse_pipe(char **ps, char *es) + { + Command *cmd = parse_exec(ps, es); + if (peek(ps, es, "|")) + { + get_token(ps, es, 0, 0); + cmd = new PipeCommand(cmd, parse_pipe(ps, es)); + } + return cmd; + } + + static Command *parse_exec(char **ps, char *es) + { + char *q, *eq; + int tok, argc; + ExecCommand *cmd = new ExecCommand(); + Command *ret = cmd; + + argc = 0; + ret = parse_redirs(ret, ps, es); + while (!peek(ps, es, "|)&;")) + { + if ((tok = get_token(ps, es, &q, &eq)) == 0) + break; + if (tok != 'a') + panic("syntax"); + + cmd->argv[argc] = q; + *eq = 0; // Temp + + argc++; + if (argc >= MAX_ARGS) + panic("too many args"); + ret = parse_redirs(ret, ps, es); + } + cmd->argv[argc] = 0; + return ret; + } + + static Command *parse_redirs(Command *cmd, char **ps, char *es) + { + int tok; + char *q, *eq; + + while (peek(ps, es, "<>")) + { + tok = get_token(ps, es, 0, 0); + if (get_token(ps, es, &q, &eq) != 'a') + panic("missing file for redirection"); + + *eq = 0; // Null terminate filename immediately + + switch (tok) + { + case '<': + cmd = new RedirCommand(cmd, q, eq, O_RDONLY, 0); + break; + case '>': + cmd = new RedirCommand(cmd, q, eq, O_WRONLY | O_CREATE | O_TRUNC, 1); + break; + case '+': // >> + cmd = new RedirCommand(cmd, q, eq, O_WRONLY | O_CREATE, 1); // Append not fully supported in simple OS yet? + break; + } + } + return cmd; + } +}; + +int getcmd(char *buf, int nbuf) +{ + write(1, "$ ", 2); + memset(buf, 0, nbuf); + + int i = 0; + while (i < nbuf - 1) + { + char c; + int n = read(0, &c, 1); + if (n <= 0) + return -1; + + if (c == '\b' || c == 127) + { + if (i > 0) + { + write(1, "\b \b", 3); + i--; + } + } + else if (c == '\n' || c == '\r') + { + write(1, "\n", 1); + buf[i] = 0; + return 0; + } + else + { + write(1, &c, 1); + buf[i++] = c; + } + } + return -1; +} + +int main() +{ + static char buf[100]; + + // int fd; + // while ((fd = open("console", O_RDWR)) >= 0) + // { + // if (fd >= 3) + // { + // close(fd); + // break; + // } + // } + + printf("\n[Lume Shell] Initialized! \n"); + + while (getcmd(buf, sizeof(buf)) >= 0) + { + if (buf[0] == 'c' && buf[1] == 'd' && buf[2] == ' ') + { + buf[strlen(buf) - 1] = 0; // chop \n + if (chdir(buf + 3) < 0) + { + printf("cannot cd %s\n", buf + 3); + } + continue; + } + + if (fork_or_panic() == 0) + { + Command *cmd = Parser::parse(buf); + if (cmd) + { + cmd->run(); + delete cmd; + } + exit(0); + } + wait(0); + } + return 0; +}
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