-
Notifications
You must be signed in to change notification settings - Fork 0
/
builtins.c
168 lines (138 loc) · 3.19 KB
/
builtins.c
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
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
//File for shell built-ins
/*The handling for built-ins is maily based on the code at tutorial
https://brennan.io/2015/01/16/write-a-shell-in-c/
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "builtins.h"
#include "parse.h"
extern char **environ;
char *builtins[] = {
"cd",
"echo",
"jobs",
"pwd",
"setenv",
"unsetenv",
"where",
"logout",
};
//The order of function pointers should remain same as the order of commands in 'builtins' array
int (*builtin_funcs[]) (Cmd) = {
&builtin_cd,
&builtin_echo,
&builtin_jobs,
&builtin_pwd,
&builtin_setenv,
&builtin_unsetenv,
&builtin_where,
&builtin_logout,
};
int num_builtins() {
return sizeof(builtins) / sizeof(char *);
}
int is_builtin(char* arg){
int i;
if(arg == NULL){
//Blank command entered
return 0;
}
for (i = 0; i < num_builtins(); i++) {
if (strcmp(arg, builtins[i]) == 0) {
//(i+1) is returned because to avoid 0 being returned on match with 0th index.
return (i+1);
}
}
return 0;
}
int exec_builtin(Cmd c, int infile_fd, int outfile_fd, int index){
if (infile_fd != STDIN_FILENO){
dup2 (infile_fd, STDIN_FILENO);
close (infile_fd);
}
if (outfile_fd != STDOUT_FILENO){
dup2 (outfile_fd, STDOUT_FILENO);
close (outfile_fd);
}
//1 subtracted from index as index was passed after adding +1 in `is_builtin`
return (*builtin_funcs[index - 1])(c);
}
int builtin_cd(Cmd cmd){
char** args = cmd->args;
char* dir_name;
if (args[1] == NULL) {
dir_name = getenv("HOME");
} else {
dir_name = args[1];
}
if (chdir(dir_name) != 0) {
perror("ush");
}
return 1;
}
int builtin_echo(Cmd cmd){
//Path($) expansion is not handled
char** args = cmd->args;
int i;
for (i=1; i < cmd->nargs; i++){
printf("%s ",args[i]);
}
printf("\n");
return 1;
}
int builtin_jobs(Cmd cmd){
return 1;
}
int builtin_pwd(Cmd cmd){
char curr_dir[256];
if( getcwd(curr_dir,256) != 0)
printf("%s\n",curr_dir);
else
printf("Error in pwd\n");
return 1;
}
int builtin_setenv(Cmd cmd){
char** args = cmd->args;
if (args[1] == NULL){ //setenv called with no args
//Print environment variables
int i;
for(i=0; environ[i]; i++){
printf("%s\n", environ[i]);
}
} else if(args[2] == NULL){ //setenv called with 1 arg, set it to NULL
return setenv(args[1], (char *)"", 1);
}else{ // setenv called with both args
return setenv(args[1],args[2],1);
}
return 1;
}
int builtin_unsetenv(Cmd cmd){
return unsetenv(cmd->args[1]);
}
int builtin_where(Cmd cmd){
char** args = cmd->args;
int i;
for (i=1; i < cmd->nargs; i++){
if(is_builtin(args[i])){
printf("%s is a shell built-in command\n",args[i]);
}
char cmd_path[1024], curr_path[256];
char* path = getenv("PATH");
strcpy(cmd_path, path);
char* token = strtok(cmd_path, ":");
while(token != NULL){
strcpy(curr_path,token);
strcat(curr_path, "/");
strcat(curr_path, args[i]);
if(access(curr_path, F_OK) == 0)
printf("%s\n",curr_path);
token = strtok(NULL, ":");
}
}
}
int builtin_logout(Cmd cmd){
exit(0);
//return 1;
}