summaryrefslogtreecommitdiff
path: root/shell.c
blob: c3bf8ec38a3e310a87df3831fb079094462abd81 (plain)
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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
#include "cache.h"
#include "quote.h"
#include "exec_cmd.h"
#include "strbuf.h"
#include "run-command.h"

#define COMMAND_DIR "git-shell-commands"
#define HELP_COMMAND COMMAND_DIR "/help"
#define NOLOGIN_COMMAND COMMAND_DIR "/no-interactive-login"

static int do_generic_cmd(const char *me, char *arg)
{
	const char *my_argv[4];

	setup_path();
	if (!arg || !(arg = sq_dequote(arg)) || *arg == '-')
		die("bad argument");
	if (!starts_with(me, "git-"))
		die("bad command");

	my_argv[0] = me + 4;
	my_argv[1] = arg;
	my_argv[2] = NULL;

	return execv_git_cmd(my_argv);
}

static int do_cvs_cmd(const char *me, char *arg)
{
	const char *cvsserver_argv[3] = {
		"cvsserver", "server", NULL
	};

	if (!arg || strcmp(arg, "server"))
		die("git-cvsserver only handles server: %s", arg);

	setup_path();
	return execv_git_cmd(cvsserver_argv);
}

static int is_valid_cmd_name(const char *cmd)
{
	/* Test command contains no . or / characters */
	return cmd[strcspn(cmd, "./")] == '\0';
}

static char *make_cmd(const char *prog)
{
	return xstrfmt("%s/%s", COMMAND_DIR, prog);
}

static void cd_to_homedir(void)
{
	const char *home = getenv("HOME");
	if (!home)
		die("could not determine user's home directory; HOME is unset");
	if (chdir(home) == -1)
		die("could not chdir to user's home directory");
}

static void run_shell(void)
{
	int done = 0;
	static const char *help_argv[] = { HELP_COMMAND, NULL };

	if (!access(NOLOGIN_COMMAND, F_OK)) {
		/* Interactive login disabled. */
		const char *argv[] = { NOLOGIN_COMMAND, NULL };
		int status;

		status = run_command_v_opt(argv, 0);
		if (status < 0)
			exit(127);
		exit(status);
	}

	/* Print help if enabled */
	run_command_v_opt(help_argv, RUN_SILENT_EXEC_FAILURE);

	do {
		struct strbuf line = STRBUF_INIT;
		const char *prog;
		char *full_cmd;
		char *rawargs;
		char *split_args;
		const char **argv;
		int code;
		int count;

		fprintf(stderr, "git> ");
		if (strbuf_getline(&line, stdin, '\n') == EOF) {
			fprintf(stderr, "\n");
			strbuf_release(&line);
			break;
		}
		strbuf_trim(&line);
		rawargs = strbuf_detach(&line, NULL);
		split_args = xstrdup(rawargs);
		count = split_cmdline(split_args, &argv);
		if (count < 0) {
			fprintf(stderr, "invalid command format '%s': %s\n", rawargs,
				split_cmdline_strerror(count));
			free(split_args);
			free(rawargs);
			continue;
		}

		prog = argv[0];
		if (!strcmp(prog, "")) {
		} else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
			   !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
			done = 1;
		} else if (is_valid_cmd_name(prog)) {
			full_cmd = make_cmd(prog);
			argv[0] = full_cmd;
			code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
			if (code == -1 && errno == ENOENT) {
				fprintf(stderr, "unrecognized command '%s'\n", prog);
			}
			free(full_cmd);
		} else {
			fprintf(stderr, "invalid command format '%s'\n", prog);
		}

		free(argv);
		free(rawargs);
	} while (!done);
}

static struct commands {
	const char *name;
	int (*exec)(const char *me, char *arg);
} cmd_list[] = {
	{ "git-receive-pack", do_generic_cmd },
	{ "git-upload-pack", do_generic_cmd },
	{ "git-upload-archive", do_generic_cmd },
	{ "cvs", do_cvs_cmd },
	{ NULL },
};

int main(int argc, char **argv)
{
	char *prog;
	const char **user_argv;
	struct commands *cmd;
	int count;

	git_setup_gettext();

	git_extract_argv0_path(argv[0]);

	/*
	 * Always open file descriptors 0/1/2 to avoid clobbering files
	 * in die().  It also avoids messing up when the pipes are dup'ed
	 * onto stdin/stdout/stderr in the child processes we spawn.
	 */
	sanitize_stdfds();

	/*
	 * Special hack to pretend to be a CVS server
	 */
	if (argc == 2 && !strcmp(argv[1], "cvs server")) {
		argv--;
	} else if (argc == 1) {
		/* Allow the user to run an interactive shell */
		cd_to_homedir();
		if (access(COMMAND_DIR, R_OK | X_OK) == -1) {
			die("Interactive git shell is not enabled.\n"
			    "hint: ~/" COMMAND_DIR " should exist "
			    "and have read and execute access.");
		}
		run_shell();
		exit(0);
	} else if (argc != 3 || strcmp(argv[1], "-c")) {
		/*
		 * We do not accept any other modes except "-c" followed by
		 * "cmd arg", where "cmd" is a very limited subset of git
		 * commands or a command in the COMMAND_DIR
		 */
		die("Run with no arguments or with -c cmd");
	}

	prog = xstrdup(argv[2]);
	if (!strncmp(prog, "git", 3) && isspace(prog[3]))
		/* Accept "git foo" as if the caller said "git-foo". */
		prog[3] = '-';

	for (cmd = cmd_list ; cmd->name ; cmd++) {
		int len = strlen(cmd->name);
		char *arg;
		if (strncmp(cmd->name, prog, len))
			continue;
		arg = NULL;
		switch (prog[len]) {
		case '\0':
			arg = NULL;
			break;
		case ' ':
			arg = prog + len + 1;
			break;
		default:
			continue;
		}
		exit(cmd->exec(cmd->name, arg));
	}

	cd_to_homedir();
	count = split_cmdline(prog, &user_argv);
	if (count >= 0) {
		if (is_valid_cmd_name(user_argv[0])) {
			prog = make_cmd(user_argv[0]);
			user_argv[0] = prog;
			execv(user_argv[0], (char *const *) user_argv);
		}
		free(prog);
		free(user_argv);
		die("unrecognized command '%s'", argv[2]);
	} else {
		free(prog);
		die("invalid command format '%s': %s", argv[2],
		    split_cmdline_strerror(count));
	}
}