135 lines
2.6 KiB
C
135 lines
2.6 KiB
C
#include "execution.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "../utils/ast/ast.h"
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/**
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* @brief converts a linked list of command arguments to an argv array. Don't
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* forget to free the result
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*
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* @param cmd_list Linked list of command arguments
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* @return char** Array of command arguments suitable for execvp. Terminated by
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* NULL
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*/
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static char **list_to_argv(struct list *cmd_list)
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{
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size_t len = 0;
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struct list *cur = cmd_list;
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while (cur)
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{
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len++;
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cur = cur->next;
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}
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char **argv = calloc(len + 1, sizeof(char *));
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if (!argv)
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{
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return NULL;
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}
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cur = cmd_list;
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for (size_t i = 0; i < len; i++)
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{
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argv[i] = (char *)cur->data;
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cur = cur->next;
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}
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argv[len] = NULL;
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return argv;
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}
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/**
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* @brief Executes a command represented by an ast_cmd structure
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*
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* @param cmd The command to execute
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* @return int The exit status of the command
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*/
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static int exec_command(struct ast_cmd *cmd)
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{
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if (!cmd || !(cmd->cmd))
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{
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return -1;
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}
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char **argv = list_to_argv(cmd->cmd);
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if (!argv || !(argv[0]))
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{
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free(argv);
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return -1;
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}
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pid_t pid = fork();
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if (pid < 0) // Fork failed
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{
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perror("fork");
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free(argv);
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return -1;
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}
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if (pid == 0) // If child process
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{
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execvp(argv[0], argv);
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perror("execvp"); // If execvp returns, there was an error
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exit(EXIT_FAILURE); // Exit child process
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}
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int status = 0;
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waitpid(pid, &status, 0);
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free(argv);
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if (WIFEXITED(status))
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{
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return WEXITSTATUS(status);
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}
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return -1; // Should not happen
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}
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/**
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* @brief Executes the AST returned by the parser
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*
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* @param ast The AST to execute
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* @return int The exit status of the last executed command.
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*/
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int execution(struct ast *ast)
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{
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if (!ast)
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{
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return 0;
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}
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switch (ast->type)
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{
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case AST_END: {
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return 0;
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}
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case AST_CMD: {
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struct ast_cmd *cmd = ast->data->ast_cmd; // Cast implicit
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return exec_command(cmd); // It's recursive
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}
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case AST_IF: {
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struct ast_if *if_node =
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ast->data->ast_if; // We cast the union to ast_if
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int cond = execution(if_node->condition);
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if (cond == 0) // True
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{
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return execution(if_node->then_clause);
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}
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else // False
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{
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return execution(if_node->else_clause);
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}
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}
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default: {
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return -1; // Should not happen
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}
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}
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}
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