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dshlib.c 7.30 KiB
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdbool.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <errno.h>
#include "dshlib.h"
int numInstanceOf(char *str, const char c) {
int count = 0;
while (*str != '\0') {
if (*str == c) count++;
str++;
}
return count;
}
int alloc_cmd_buff(cmd_buff_t *cmd_buff) {
if (cmd_buff == NULL) {
return ERR_MEMORY;
}
cmd_buff->argc = 0;
cmd_buff->argv = (char**)malloc(CMD_ARGV_MAX * sizeof(char *));
if (cmd_buff->argv == NULL) {
free(cmd_buff);
return ERR_MEMORY;
}
for (int i = 0; i < CMD_ARGV_MAX; i++) {
cmd_buff->argv[i] = (char *)malloc(ARG_MAX);
if (cmd_buff->argv[i] == NULL) {
for (int j = 0; j < i; j++) {
free(cmd_buff->argv[j]);
}
free(cmd_buff->argv);
return ERR_MEMORY;
}
}
cmd_buff->_cmd_buffer = (char *)malloc(SH_CMD_MAX);
if (cmd_buff->_cmd_buffer == NULL) {
free(cmd_buff->_cmd_buffer);
for (int i = 0; i < CMD_ARGV_MAX; i++) {
free(cmd_buff->argv[i]);
}
free(cmd_buff->argv);
return ERR_MEMORY;
}
return OK_EXIT;
}
int free_cmd_buff(cmd_buff_t *cmd_buff) {
if (cmd_buff == NULL) return OK_EXIT;
free(cmd_buff->_cmd_buffer);
cmd_buff->_cmd_buffer = NULL;
for (int i = 0; i < CMD_ARGV_MAX - 1; i++) free(cmd_buff->argv[i]);
free(cmd_buff->argv);
free(cmd_buff);
return OK_EXIT;
}
int clear_cmd_buff(cmd_buff_t *cmd_buff) {
cmd_buff->argc = 0;
memset(cmd_buff->_cmd_buffer, 0, SH_CMD_MAX);
for (int i = 0; i < CMD_ARGV_MAX; i++) cmd_buff->argv[i] = NULL;
return OK_EXIT;
}
char* trim_whitespace(char *str) {
int start = 0;
while (isspace((unsigned char)str[start])) {
start++;
}
int end = strlen(str) - 1;
while (end > start && isspace((unsigned char)str[end])) {
end--;
}
int j = 0;
for (int i = start; i <= end; i++) {
str[j++] = str[i];
}
str[j] = '\0';
return str;
}
int build_cmd_buff(char *cmd_line, cmd_buff_t *cmd_buff) {
if ((int)strlen(cmd_line) > SH_CMD_MAX) return ERR_CMD_OR_ARGS_TOO_BIG;
if ((int)strlen(cmd_line) == 0) return WARN_NO_CMDS;
if (cmd_buff->_cmd_buffer) free(cmd_buff->_cmd_buffer);
cmd_buff->_cmd_buffer = strdup(trim_whitespace(cmd_line));
if (cmd_buff->_cmd_buffer == NULL) return ERR_MEMORY;
char *token = cmd_buff->_cmd_buffer;
bool quotes = false;
char *p = NULL;
while (*token) {
if (*token == DOUBLE_QUOTE_CHAR) {
quotes = !quotes;
if (quotes) p = token + 1;
else *token = '\0';
} else if (!quotes && (*token == SPACE_CHAR || *token == '\t')) {
*token = '\0';
if (p != NULL) {
cmd_buff->argv[cmd_buff->argc++] = p;
p = NULL;
}
} else if (p == NULL) {
p = token;
}
token++;
}
if (p != NULL) cmd_buff->argv[cmd_buff->argc++] = p;
cmd_buff->argv[cmd_buff->argc] = NULL;
return OK_EXIT;
}
/*
* Implement your exec_local_cmd_loop function by building a loop that prompts the
* user for input. Use the SH_PROMPT constant from dshlib.h and then
* use fgets to accept user input.
*
* while(1){
* printf("%s", SH_PROMPT);
* if (fgets(cmd_buff, ARG_MAX, stdin) == NULL){
* printf("\n");
* break;
* }
* //remove the trailing \n from cmd_buff
* cmd_buff[strcspn(cmd_buff,"\n")] = '\0';
*
* //IMPLEMENT THE REST OF THE REQUIREMENTS
* }
*
* Also, use the constants in the dshlib.h in this code.
* SH_CMD_MAX maximum buffer size for user input
* EXIT_CMD constant that terminates the dsh program
* SH_PROMPT the shell prompt
* OK the command was parsed properly
* WARN_NO_CMDS the user command was empty
* ERR_TOO_MANY_COMMANDS too many pipes used
* ERR_MEMORY dynamic memory management failure
*
* errors returned
* OK No error
* ERR_MEMORY Dynamic memory management failure
* WARN_NO_CMDS No commands parsed
* ERR_TOO_MANY_COMMANDS too many pipes used
*
* console messages
* CMD_WARN_NO_CMD print on WARN_NO_CMDS
* CMD_ERR_PIPE_LIMIT print on ERR_TOO_MANY_COMMANDS
* CMD_ERR_EXECUTE print on execution failure of external command
*
* Standard Library Functions You Might Want To Consider Using (assignment 1+)
* malloc(), free(), strlen(), fgets(), strcspn(), printf()
*
* Standard Library Functions You Might Want To Consider Using (assignment 2+)
* fork(), execvp(), exit(), chdir()
*/
int exec_local_cmd_loop()
{
char *cmd_buff = malloc(ARG_MAX * sizeof(char));
int rc = 0;
cmd_buff_t *cmd = malloc(sizeof(cmd_buff_t));
if ((rc = alloc_cmd_buff(cmd)) != OK_EXIT) exit(rc);
// TODO IMPLEMENT MAIN LOOP
while(1){
printf("%s", SH_PROMPT);
if (fgets(cmd_buff, ARG_MAX, stdin) == NULL){
printf("\n");
break;
}
//remove the trailing \n from cmd_buff
cmd_buff[strcspn(cmd_buff,"\n")] = '\0';
//IMPLEMENT THE REST OF THE REQUIREMENTS
if (strcmp(cmd_buff, EXIT_CMD) == 0) {
exit(rc);
}
if (strcmp(cmd_buff, "rc") == 0) {
printf("%d\n", rc);
//if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
rc = 0;
continue;
}
if (strcmp(cmd_buff, "\0") == 0) {
rc = WARN_NO_CMDS;
printf(CMD_WARN_NO_CMD);
//if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
continue;
}
// TODO IMPLEMENT parsing input to cmd_buff_t *cmd_buff
if ((rc = build_cmd_buff(cmd_buff, cmd)) != OK_EXIT) {
free(cmd_buff);
free_cmd_buff(cmd);
exit(rc);
}
/*
if (strcmp(cmd->argv[0], "echo") == 0) {
for (int i = 1; i < CMD_ARGV_MAX; i++) {
printf("%s ", cmd->argv[i]);
}
printf("\n");
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
continue;
}*/
// TODO IMPLEMENT if built-in command, execute builtin logic for exit, cd (extra credit: dragon)
if (strcmp(cmd_buff, "dragon") == 0) {
print_dragon();
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
rc = 0;
continue;
}
// the cd command should chdir to the provided directory; if no directory is provided, do nothing
if (strcmp(cmd->argv[0], "cd") == 0) {
if (cmd->argc < 2) {
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
rc = 0;
continue;
}
if (chdir(cmd->argv[1]) != 0) {
perror("chdir failed");
rc = 1;
}
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
rc = 0;
continue;
}
// TODO IMPLEMENT if not built-in command, fork/exec as an external command
// for example, if the user input is "ls -l", you would fork/exec the command "ls" with the arg "-l"
pid_t pid = fork();
if (pid < 0) {
printf("fork failed");
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
continue;
} else if (pid == 0) {
execvp(cmd->argv[0], cmd->argv);
perror(CMD_ERR_EXECUTE);
exit(1);
} else {
int status;
waitpid(pid, &status, 0);
if (WIFEXITED(status)) {
rc = WEXITSTATUS(status);
} else {
rc = 1;
}
}
if ((rc = clear_cmd_buff(cmd)) != OK_EXIT) exit(rc);
}
free(cmd_buff);
free_cmd_buff(cmd);
return OK;
}