summaryrefslogtreecommitdiffstats
path: root/sub-process.c
blob: 6d4232294dbee7ad2928b0ac12e1860dcf04a12d (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
/*
 * Generic implementation of background process infrastructure.
 */
#include "sub-process.h"
#include "sigchain.h"
#include "pkt-line.h"

int cmd2process_cmp(const void *cmp_data UNUSED,
		    const struct hashmap_entry *eptr,
		    const struct hashmap_entry *entry_or_key,
		    const void *keydata UNUSED)
{
	const struct subprocess_entry *e1, *e2;

	e1 = container_of(eptr, const struct subprocess_entry, ent);
	e2 = container_of(entry_or_key, const struct subprocess_entry, ent);

	return strcmp(e1->cmd, e2->cmd);
}

struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
{
	struct subprocess_entry key;

	hashmap_entry_init(&key.ent, strhash(cmd));
	key.cmd = cmd;
	return hashmap_get_entry(hashmap, &key, ent, NULL);
}

int subprocess_read_status(int fd, struct strbuf *status)
{
	struct strbuf **pair;
	char *line;
	int len;

	for (;;) {
		len = packet_read_line_gently(fd, NULL, &line);
		if ((len < 0) || !line)
			break;
		pair = strbuf_split_str(line, '=', 2);
		if (pair[0] && pair[0]->len && pair[1]) {
			/* the last "status=<foo>" line wins */
			if (!strcmp(pair[0]->buf, "status=")) {
				strbuf_reset(status);
				strbuf_addbuf(status, pair[1]);
			}
		}
		strbuf_list_free(pair);
	}

	return (len < 0) ? len : 0;
}

void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
{
	if (!entry)
		return;

	entry->process.clean_on_exit = 0;
	kill(entry->process.pid, SIGTERM);
	finish_command(&entry->process);

	hashmap_remove(hashmap, &entry->ent, NULL);
}

static void subprocess_exit_handler(struct child_process *process)
{
	sigchain_push(SIGPIPE, SIG_IGN);
	/* Closing the pipe signals the subprocess to initiate a shutdown. */
	close(process->in);
	close(process->out);
	sigchain_pop(SIGPIPE);
	/* Finish command will wait until the shutdown is complete. */
	finish_command(process);
}

int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
	subprocess_start_fn startfn)
{
	int err;
	struct child_process *process;

	entry->cmd = cmd;
	process = &entry->process;

	child_process_init(process);
	strvec_push(&process->args, cmd);
	process->use_shell = 1;
	process->in = -1;
	process->out = -1;
	process->clean_on_exit = 1;
	process->clean_on_exit_handler = subprocess_exit_handler;
	process->trace2_child_class = "subprocess";

	err = start_command(process);
	if (err) {
		error("cannot fork to run subprocess '%s'", cmd);
		return err;
	}

	hashmap_entry_init(&entry->ent, strhash(cmd));

	err = startfn(entry);
	if (err) {
		error("initialization for subprocess '%s' failed", cmd);
		subprocess_stop(hashmap, entry);
		return err;
	}

	hashmap_add(hashmap, &entry->ent);
	return 0;
}

static int handshake_version(struct child_process *process,
			     const char *welcome_prefix, int *versions,
			     int *chosen_version)
{
	int version_scratch;
	int i;
	char *line;
	const char *p;

	if (!chosen_version)
		chosen_version = &version_scratch;

	if (packet_write_fmt_gently(process->in, "%s-client\n",
				    welcome_prefix))
		return error("Could not write client identification");
	for (i = 0; versions[i]; i++) {
		if (packet_write_fmt_gently(process->in, "version=%d\n",
					    versions[i]))
			return error("Could not write requested version");
	}
	if (packet_flush_gently(process->in))
		return error("Could not write flush packet");

	if (!(line = packet_read_line(process->out, NULL)) ||
	    !skip_prefix(line, welcome_prefix, &p) ||
	    strcmp(p, "-server"))
		return error("Unexpected line '%s', expected %s-server",
			     line ? line : "<flush packet>", welcome_prefix);
	if (!(line = packet_read_line(process->out, NULL)) ||
	    !skip_prefix(line, "version=", &p) ||
	    strtol_i(p, 10, chosen_version))
		return error("Unexpected line '%s', expected version",
			     line ? line : "<flush packet>");
	if ((line = packet_read_line(process->out, NULL)))
		return error("Unexpected line '%s', expected flush", line);

	/* Check to make sure that the version received is supported */
	for (i = 0; versions[i]; i++) {
		if (versions[i] == *chosen_version)
			break;
	}
	if (!versions[i])
		return error("Version %d not supported", *chosen_version);

	return 0;
}

static int handshake_capabilities(struct child_process *process,
				  struct subprocess_capability *capabilities,
				  unsigned int *supported_capabilities)
{
	int i;
	char *line;

	for (i = 0; capabilities[i].name; i++) {
		if (packet_write_fmt_gently(process->in, "capability=%s\n",
					    capabilities[i].name))
			return error("Could not write requested capability");
	}
	if (packet_flush_gently(process->in))
		return error("Could not write flush packet");

	while ((line = packet_read_line(process->out, NULL))) {
		const char *p;
		if (!skip_prefix(line, "capability=", &p))
			continue;

		for (i = 0;
		     capabilities[i].name && strcmp(p, capabilities[i].name);
		     i++)
			;
		if (capabilities[i].name) {
			if (supported_capabilities)
				*supported_capabilities |= capabilities[i].flag;
		} else {
			die("subprocess '%s' requested unsupported capability '%s'",
			    process->args.v[0], p);
		}
	}

	return 0;
}

int subprocess_handshake(struct subprocess_entry *entry,
			 const char *welcome_prefix,
			 int *versions,
			 int *chosen_version,
			 struct subprocess_capability *capabilities,
			 unsigned int *supported_capabilities)
{
	int retval;
	struct child_process *process = &entry->process;

	sigchain_push(SIGPIPE, SIG_IGN);

	retval = handshake_version(process, welcome_prefix, versions,
				   chosen_version) ||
		 handshake_capabilities(process, capabilities,
					supported_capabilities);

	sigchain_pop(SIGPIPE);
	return retval;
}