2022-10-19 17:42:05 +00:00
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#include <luna.h>
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#include <stdio.h>
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#include <stdlib.h>
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2022-10-19 18:34:10 +00:00
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#include <string.h>
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2022-10-19 17:42:05 +00:00
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#include <sys/wait.h>
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#include <unistd.h>
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2022-10-20 06:21:18 +00:00
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static int status = 0;
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2022-10-19 18:16:21 +00:00
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2022-10-19 17:42:05 +00:00
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typedef struct
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{
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char* buffer;
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2022-10-19 18:34:10 +00:00
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size_t size;
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size_t capacity;
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2022-10-19 17:42:05 +00:00
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} command;
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void show_prompt()
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{
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2022-10-20 06:21:18 +00:00
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if (status) { printf("%d [%ld]> ", WEXITSTATUS(status), getpid()); }
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else
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printf("[%ld]> ", getpid());
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2022-10-19 17:42:05 +00:00
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}
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2022-10-19 18:34:10 +00:00
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int command_matches(command* cmd, const char* string)
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{
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if (cmd->size <= strlen(string)) // cmd->size includes null terminator
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return 0;
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return strncmp(cmd->buffer, string, strlen(string)) == 0;
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}
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int command_matches_exactly(command* cmd, const char* string)
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{
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if (cmd->size <= strlen(string)) // cmd->size includes null terminator
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return 0;
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if (cmd->size > (strlen(string) + 1)) return 0;
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return strncmp(cmd->buffer, string, strlen(string)) == 0;
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}
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int command_match_builtins(command* cmd)
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{
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if (command_matches(cmd, "exit ")) { exit(atoi(cmd->buffer + 5)); }
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if (command_matches_exactly(cmd, "exit")) { exit(0); }
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if (command_matches_exactly(cmd, "pid"))
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{
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printf("pid %ld, ppid %ld\n", getpid(), getppid());
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return 1;
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}
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return 0;
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}
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2022-10-19 17:42:05 +00:00
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void command_expand(command* cmd, long new_capacity)
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{
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char* buffer = realloc(cmd->buffer, new_capacity);
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if (!buffer)
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{
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perror("realloc");
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exit(1);
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}
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cmd->buffer = buffer;
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cmd->capacity = new_capacity;
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}
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void command_push(command* cmd, char c)
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{
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if (cmd->size == cmd->capacity) command_expand(cmd, cmd->capacity + 8);
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cmd->buffer[cmd->size] = c;
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cmd->size++;
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}
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void command_pop(command* cmd)
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{
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cmd->size--;
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}
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void command_init(command* cmd)
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{
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cmd->buffer = malloc(5);
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cmd->capacity = 5;
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cmd->size = 0;
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}
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void command_clear(command* cmd)
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{
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free(cmd->buffer);
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return command_init(cmd);
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}
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void command_execute(command* cmd)
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{
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command_push(cmd, '\0');
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2022-10-19 18:34:10 +00:00
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if (command_match_builtins(cmd))
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{
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command_clear(cmd);
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show_prompt();
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return;
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}
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2022-10-19 17:42:05 +00:00
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pid_t child = fork();
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if (child < 0)
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{
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perror(cmd->buffer);
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command_clear(cmd);
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show_prompt();
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return;
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}
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if (child == 0)
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{
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execv(cmd->buffer, NULL);
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perror(cmd->buffer);
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exit(127);
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}
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pid_t result;
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while ((result = waitpid(child, &status, 0)) == 0) { msleep(20); }
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if (result < 0)
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{
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perror("waitpid");
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command_clear(cmd);
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show_prompt();
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return;
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}
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2022-10-19 18:16:21 +00:00
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int exit_status = WEXITSTATUS(status);
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if (exit_status == -2 || exit_status == -3) printf("(PID %ld) Segmentation fault\n", result);
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2022-10-19 17:42:05 +00:00
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command_clear(cmd);
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show_prompt();
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}
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void command_concat(command* cmd, const char* str)
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{
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while (*str)
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{
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putchar(*str);
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if (*str == '\b') { command_pop(cmd); }
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else if (*str == '\n') { command_execute(cmd); }
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else
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command_push(cmd, *str);
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str++;
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}
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}
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int main()
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{
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show_prompt();
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char buffer[33];
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command shell_command;
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command_init(&shell_command);
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while (1)
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{
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2022-10-19 18:43:04 +00:00
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size_t nread = fread(buffer, sizeof(buffer) - 1, 1, stdin);
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if (ferror(stdin))
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2022-10-19 17:42:05 +00:00
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{
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perror("fread");
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return 1;
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}
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2022-10-19 18:43:04 +00:00
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if (feof(stdin))
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{
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2022-10-19 18:43:04 +00:00
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clearerr(stdin);
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2022-10-19 17:42:05 +00:00
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msleep(20);
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continue;
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}
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buffer[nread] = 0;
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command_concat(&shell_command, buffer);
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}
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}
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