From a60b4c57078e17d5ecabf1ac92faa92ca5aab1c3 Mon Sep 17 00:00:00 2001
From: jl4589 <jl4589@drexel.edu>
Date: Tue, 4 Mar 2025 17:06:00 -0500
Subject: [PATCH] Cmd loop had a problem I think
---
Assignment-05/starter/dshlib.c | 122 ++++++++++++++-------------------
1 file changed, 52 insertions(+), 70 deletions(-)
diff --git a/Assignment-05/starter/dshlib.c b/Assignment-05/starter/dshlib.c
index 30a4cbd..f02f23a 100644
--- a/Assignment-05/starter/dshlib.c
+++ b/Assignment-05/starter/dshlib.c
@@ -174,91 +174,73 @@ int parse_pipeline(char *cmd_line, command_list_t *clist) {
return OK;
}
-int exec_local_cmd_loop() {
- char cmd_buff[SH_CMD_MAX];
- int rc = OK;
-
- while (1) {
- printf("%s", SH_PROMPT);
+int execute_pipeline(command_list_t *cmd_list) {
+ int num_commands = cmd_list->num;
+ int pipefd[2];
+ int prev_pipe_read = -1;
+ pid_t pids[num_commands];
- if (fgets(cmd_buff, SH_CMD_MAX, stdin) == NULL) {
- printf("\n");
- break;
+ for (int i = 0; i < num_commands; i++) {
+ if (i < num_commands - 1) {
+ if (pipe(pipefd) == -1) {
+ perror("pipe");
+ return ERR_MEMORY;
+ }
}
- cmd_buff[strcspn(cmd_buff, "\n")] = '\0';
-
- if (strlen(cmd_buff) == 0) {
- printf("%s\n", CMD_WARN_NO_CMD);
- rc = WARN_NO_CMDS;
- continue;
+ pids[i] = fork();
+ if (pids[i] == -1) {
+ perror("fork");
+ return ERR_MEMORY;
}
- if (strstr(cmd_buff, "|") != NULL) {
- command_list_t cmd_list;
- if (parse_pipeline(cmd_buff, &cmd_list) != OK) {
- fprintf(stderr, "%s\n", CMD_ERR_PIPE_LIMIT);
- rc = ERR_TOO_MANY_COMMANDS;
- continue;
- }
-
- if (execute_pipeline(&cmd_list) != OK) {
- fprintf(stderr, "%s\n", CMD_ERR_PIPE_LIMIT);
- rc = ERR_MEMORY;
+ if (pids[i] == 0) {
+ if (prev_pipe_read != -1) {
+ dup2(prev_pipe_read, STDIN_FILENO);
+ close(prev_pipe_read);
}
- for (int i = 0; i < cmd_list.num; i++) {
- free(cmd_list.commands[i]._cmd_buffer);
- }
- } else {
- cmd_buff_t cmd;
- if (build_cmd_buff(cmd_buff, &cmd) != OK) {
- fprintf(stderr, "%s\n", CMD_ERR_PIPE_LIMIT);
- rc = ERR_MEMORY;
- continue;
+ if (i < num_commands - 1) {
+ dup2(pipefd[1], STDOUT_FILENO);
+ close(pipefd[1]);
+ close(pipefd[0]);
}
- if (strcmp(cmd.argv[0], EXIT_CMD) == 0) {
- free(cmd._cmd_buffer);
- break;
+ cmd_buff_t *cmd = &cmd_list->commands[i];
+ execvp(cmd->argv[0], cmd->argv);
+ perror("execvp");
+ exit(EXIT_FAILURE);
+ } else {
+ if (prev_pipe_read != -1) {
+ close(prev_pipe_read);
}
- if (strcmp(cmd.argv[0], "cd") == 0) {
- if (cmd.argc == 1) {
- chdir(getenv("HOME"));
- } else if (cmd.argc == 2) {
- if (chdir(cmd.argv[1]) != 0) {
- perror("cd");
- }
- } else {
- fprintf(stderr, "%s\n", CMD_ERR_PIPE_LIMIT);
- }
- free(cmd._cmd_buffer);
- continue;
+ if (i < num_commands - 1) {
+ prev_pipe_read = pipefd[0];
+ close(pipefd[1]);
}
+ }
+ }
- pid_t pid = fork();
- if (pid < 0) {
- perror("fork failed");
- rc = ERR_MEMORY;
- } else if (pid == 0) {
- execvp(cmd.argv[0], cmd.argv);
- perror("execvp failed");
- exit(EXIT_FAILURE);
- } else {
- int status;
- wait(&status);
-
- if (WIFEXITED(status)) {
- if (WEXITSTATUS(status) != 0) {
- fprintf(stderr, "Command failed with exit code %d\n", WEXITSTATUS(status));
- }
- }
+ if (prev_pipe_read != -1) {
+ char buffer[1024];
+ ssize_t bytes_read;
+ while ((bytes_read = read(prev_pipe_read, buffer, sizeof(buffer) - 1)) {
+ if (bytes_read < 0) {
+ perror("read");
+ break;
}
-
- free(cmd._cmd_buffer);
+ buffer[bytes_read] = '\0';
+ printf("%s", buffer);
}
+ close(prev_pipe_read);
}
- return rc;
+
+ for (int i = 0; i < num_commands; i++) {
+ waitpid(pids[i], NULL, 0);
+ }
+
+ return OK;
}
+
--
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