unpack-trees: add a note about path invalidation
[git] / shell.c
1 #include "cache.h"
2 #include "quote.h"
3 #include "exec-cmd.h"
4 #include "strbuf.h"
5 #include "run-command.h"
6 #include "alias.h"
7
8 #define COMMAND_DIR "git-shell-commands"
9 #define HELP_COMMAND COMMAND_DIR "/help"
10 #define NOLOGIN_COMMAND COMMAND_DIR "/no-interactive-login"
11
12 static int do_generic_cmd(const char *me, char *arg)
13 {
14         const char *my_argv[4];
15
16         setup_path();
17         if (!arg || !(arg = sq_dequote(arg)) || *arg == '-')
18                 die("bad argument");
19         if (!starts_with(me, "git-"))
20                 die("bad command");
21
22         my_argv[0] = me + 4;
23         my_argv[1] = arg;
24         my_argv[2] = NULL;
25
26         return execv_git_cmd(my_argv);
27 }
28
29 static int is_valid_cmd_name(const char *cmd)
30 {
31         /* Test command contains no . or / characters */
32         return cmd[strcspn(cmd, "./")] == '\0';
33 }
34
35 static char *make_cmd(const char *prog)
36 {
37         return xstrfmt("%s/%s", COMMAND_DIR, prog);
38 }
39
40 static void cd_to_homedir(void)
41 {
42         const char *home = getenv("HOME");
43         if (!home)
44                 die("could not determine user's home directory; HOME is unset");
45         if (chdir(home) == -1)
46                 die("could not chdir to user's home directory");
47 }
48
49 static void run_shell(void)
50 {
51         int done = 0;
52         static const char *help_argv[] = { HELP_COMMAND, NULL };
53
54         if (!access(NOLOGIN_COMMAND, F_OK)) {
55                 /* Interactive login disabled. */
56                 const char *argv[] = { NOLOGIN_COMMAND, NULL };
57                 int status;
58
59                 status = run_command_v_opt(argv, 0);
60                 if (status < 0)
61                         exit(127);
62                 exit(status);
63         }
64
65         /* Print help if enabled */
66         run_command_v_opt(help_argv, RUN_SILENT_EXEC_FAILURE);
67
68         do {
69                 struct strbuf line = STRBUF_INIT;
70                 const char *prog;
71                 char *full_cmd;
72                 char *rawargs;
73                 char *split_args;
74                 const char **argv;
75                 int code;
76                 int count;
77
78                 fprintf(stderr, "git> ");
79                 if (strbuf_getline_lf(&line, stdin) == EOF) {
80                         fprintf(stderr, "\n");
81                         strbuf_release(&line);
82                         break;
83                 }
84                 strbuf_trim(&line);
85                 rawargs = strbuf_detach(&line, NULL);
86                 split_args = xstrdup(rawargs);
87                 count = split_cmdline(split_args, &argv);
88                 if (count < 0) {
89                         fprintf(stderr, "invalid command format '%s': %s\n", rawargs,
90                                 split_cmdline_strerror(count));
91                         free(split_args);
92                         free(rawargs);
93                         continue;
94                 }
95
96                 prog = argv[0];
97                 if (!strcmp(prog, "")) {
98                 } else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
99                            !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
100                         done = 1;
101                 } else if (is_valid_cmd_name(prog)) {
102                         full_cmd = make_cmd(prog);
103                         argv[0] = full_cmd;
104                         code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
105                         if (code == -1 && errno == ENOENT) {
106                                 fprintf(stderr, "unrecognized command '%s'\n", prog);
107                         }
108                         free(full_cmd);
109                 } else {
110                         fprintf(stderr, "invalid command format '%s'\n", prog);
111                 }
112
113                 free(argv);
114                 free(rawargs);
115         } while (!done);
116 }
117
118 static struct commands {
119         const char *name;
120         int (*exec)(const char *me, char *arg);
121 } cmd_list[] = {
122         { "git-receive-pack", do_generic_cmd },
123         { "git-upload-pack", do_generic_cmd },
124         { "git-upload-archive", do_generic_cmd },
125         { NULL },
126 };
127
128 int cmd_main(int argc, const char **argv)
129 {
130         char *prog;
131         const char **user_argv;
132         struct commands *cmd;
133         int count;
134
135         /*
136          * Special hack to pretend to be a CVS server
137          */
138         if (argc == 2 && !strcmp(argv[1], "cvs server")) {
139                 argv--;
140         } else if (argc == 1) {
141                 /* Allow the user to run an interactive shell */
142                 cd_to_homedir();
143                 if (access(COMMAND_DIR, R_OK | X_OK) == -1) {
144                         die("Interactive git shell is not enabled.\n"
145                             "hint: ~/" COMMAND_DIR " should exist "
146                             "and have read and execute access.");
147                 }
148                 run_shell();
149                 exit(0);
150         } else if (argc != 3 || strcmp(argv[1], "-c")) {
151                 /*
152                  * We do not accept any other modes except "-c" followed by
153                  * "cmd arg", where "cmd" is a very limited subset of git
154                  * commands or a command in the COMMAND_DIR
155                  */
156                 die("Run with no arguments or with -c cmd");
157         }
158
159         prog = xstrdup(argv[2]);
160         if (!strncmp(prog, "git", 3) && isspace(prog[3]))
161                 /* Accept "git foo" as if the caller said "git-foo". */
162                 prog[3] = '-';
163
164         for (cmd = cmd_list ; cmd->name ; cmd++) {
165                 int len = strlen(cmd->name);
166                 char *arg;
167                 if (strncmp(cmd->name, prog, len))
168                         continue;
169                 arg = NULL;
170                 switch (prog[len]) {
171                 case '\0':
172                         arg = NULL;
173                         break;
174                 case ' ':
175                         arg = prog + len + 1;
176                         break;
177                 default:
178                         continue;
179                 }
180                 exit(cmd->exec(cmd->name, arg));
181         }
182
183         cd_to_homedir();
184         count = split_cmdline(prog, &user_argv);
185         if (count >= 0) {
186                 if (is_valid_cmd_name(user_argv[0])) {
187                         prog = make_cmd(user_argv[0]);
188                         user_argv[0] = prog;
189                         execv(user_argv[0], (char *const *) user_argv);
190                 }
191                 free(prog);
192                 free(user_argv);
193                 die("unrecognized command '%s'", argv[2]);
194         } else {
195                 free(prog);
196                 die("invalid command format '%s': %s", argv[2],
197                     split_cmdline_strerror(count));
198         }
199 }