File size: 2,750 Bytes
4559903 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 | #include "shell.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/wait.h>
static char **split(char *line, int *arg_count, char *delim) {
char *copy = malloc(strlen(line));
strcpy(copy, line);
char **words = NULL;
char *word = strtok(copy, delim);
size_t counter = 0;
while(word != NULL) {
words = (char**)realloc(words, (counter+1)*sizeof(char*));
words[counter] = (char*)malloc(strlen(word)+1);
strcpy(words[counter], word);
counter++;
word = strtok(NULL, delim);
}
words = (char**)realloc(words, (counter+1)*sizeof(char*));
words[counter] = NULL;
*arg_count = counter;
free(copy);
return words;
}
static bool dir_exists(char path[]) {
struct stat sb;
bool exists = false;
if(stat(path, &sb) == 0 && S_ISDIR(sb.st_mode)) {
exists = true;
}
return exists;
}
static bool run_builtin(char **args, int arg_count) {
bool is_builtin_command = false;
if(strcmp(args[0], "cd") == 0) {
if((arg_count > 1 && strcmp(args[1], "~") == 0) || arg_count == 1) {
chdir(getenv("HOME"));
}
else {
if(dir_exists(args[1])) {
chdir(args[1]);
}
else {
fprintf(stderr, "dtsh: %s: directory does not exist\n", args[1]);
}
}
is_builtin_command = true;
}
else if(strcmp(args[0], "exit") == 0) {
exit(1);
}
return is_builtin_command;
}
static char **redirect(char **args, int arg_count) {
if(strcmp(args[arg_count-2], ">") == 0) {
int fd = open(args[arg_count-1], O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
dup2(fd, fileno(stdout));
args[arg_count-2] = 0;
args[arg_count-1] = 0;
}
else if(strcmp(args[arg_count-2], ">>") == 0) {
int fd = open(args[arg_count-1], O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
dup2(fd, fileno(stdout));
args[arg_count-2] = 0;
args[arg_count-1] = 0;
}
else if(strcmp(args[arg_count-2], "<") == 0) {
int fd = open(args[arg_count-1], O_RDONLY);
dup2(fd, fileno(stdin));
args[arg_count-2] = 0;
args[arg_count-1] = 0;
}
return args;
}
static void execute(char *line) {
int arg_count;
char **args = split(line, &arg_count, " ");
if(!run_builtin(args, arg_count)) {
pid_t pid = fork();
if(pid == 0) {
if(arg_count >= 3) {
args = redirect(args, arg_count);
}
shell_register_current_pid(pid);
execvp(args[0], args);
fprintf(stderr, "error: couldn't execute %s\n", args[0]);
}
else {
int status;
wait(&status);
}
}
}
void shell_execute(char *line) {
int arg_count;
char **args = split(line, &arg_count, " ");
execute(line);
free(args);
}
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