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1 | /* | |
2 | * Generic implementation of background process infrastructure. | |
3 | */ | |
4 | #include "git-compat-util.h" | |
5 | #include "sub-process.h" | |
6 | #include "sigchain.h" | |
7 | #include "pkt-line.h" | |
8 | ||
9 | int cmd2process_cmp(const void *cmp_data UNUSED, | |
10 | const struct hashmap_entry *eptr, | |
11 | const struct hashmap_entry *entry_or_key, | |
12 | const void *keydata UNUSED) | |
13 | { | |
14 | const struct subprocess_entry *e1, *e2; | |
15 | ||
16 | e1 = container_of(eptr, const struct subprocess_entry, ent); | |
17 | e2 = container_of(entry_or_key, const struct subprocess_entry, ent); | |
18 | ||
19 | return strcmp(e1->cmd, e2->cmd); | |
20 | } | |
21 | ||
22 | struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd) | |
23 | { | |
24 | struct subprocess_entry key; | |
25 | ||
26 | hashmap_entry_init(&key.ent, strhash(cmd)); | |
27 | key.cmd = cmd; | |
28 | return hashmap_get_entry(hashmap, &key, ent, NULL); | |
29 | } | |
30 | ||
31 | int subprocess_read_status(int fd, struct strbuf *status) | |
32 | { | |
33 | struct strbuf **pair; | |
34 | char *line; | |
35 | int len; | |
36 | ||
37 | for (;;) { | |
38 | len = packet_read_line_gently(fd, NULL, &line); | |
39 | if ((len < 0) || !line) | |
40 | break; | |
41 | pair = strbuf_split_str(line, '=', 2); | |
42 | if (pair[0] && pair[0]->len && pair[1]) { | |
43 | /* the last "status=<foo>" line wins */ | |
44 | if (!strcmp(pair[0]->buf, "status=")) { | |
45 | strbuf_reset(status); | |
46 | strbuf_addbuf(status, pair[1]); | |
47 | } | |
48 | } | |
49 | strbuf_list_free(pair); | |
50 | } | |
51 | ||
52 | return (len < 0) ? len : 0; | |
53 | } | |
54 | ||
55 | void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry) | |
56 | { | |
57 | if (!entry) | |
58 | return; | |
59 | ||
60 | entry->process.clean_on_exit = 0; | |
61 | kill(entry->process.pid, SIGTERM); | |
62 | finish_command(&entry->process); | |
63 | ||
64 | hashmap_remove(hashmap, &entry->ent, NULL); | |
65 | } | |
66 | ||
67 | static void subprocess_exit_handler(struct child_process *process) | |
68 | { | |
69 | sigchain_push(SIGPIPE, SIG_IGN); | |
70 | /* Closing the pipe signals the subprocess to initiate a shutdown. */ | |
71 | close(process->in); | |
72 | close(process->out); | |
73 | sigchain_pop(SIGPIPE); | |
74 | /* Finish command will wait until the shutdown is complete. */ | |
75 | finish_command(process); | |
76 | } | |
77 | ||
78 | int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd, | |
79 | subprocess_start_fn startfn) | |
80 | { | |
81 | int err; | |
82 | struct child_process *process; | |
83 | ||
84 | entry->cmd = cmd; | |
85 | process = &entry->process; | |
86 | ||
87 | child_process_init(process); | |
88 | strvec_push(&process->args, cmd); | |
89 | process->use_shell = 1; | |
90 | process->in = -1; | |
91 | process->out = -1; | |
92 | process->clean_on_exit = 1; | |
93 | process->clean_on_exit_handler = subprocess_exit_handler; | |
94 | process->trace2_child_class = "subprocess"; | |
95 | ||
96 | err = start_command(process); | |
97 | if (err) { | |
98 | error("cannot fork to run subprocess '%s'", cmd); | |
99 | return err; | |
100 | } | |
101 | ||
102 | hashmap_entry_init(&entry->ent, strhash(cmd)); | |
103 | ||
104 | err = startfn(entry); | |
105 | if (err) { | |
106 | error("initialization for subprocess '%s' failed", cmd); | |
107 | subprocess_stop(hashmap, entry); | |
108 | return err; | |
109 | } | |
110 | ||
111 | hashmap_add(hashmap, &entry->ent); | |
112 | return 0; | |
113 | } | |
114 | ||
115 | static int handshake_version(struct child_process *process, | |
116 | const char *welcome_prefix, int *versions, | |
117 | int *chosen_version) | |
118 | { | |
119 | int version_scratch; | |
120 | int i; | |
121 | char *line; | |
122 | const char *p; | |
123 | ||
124 | if (!chosen_version) | |
125 | chosen_version = &version_scratch; | |
126 | ||
127 | if (packet_write_fmt_gently(process->in, "%s-client\n", | |
128 | welcome_prefix)) | |
129 | return error("Could not write client identification"); | |
130 | for (i = 0; versions[i]; i++) { | |
131 | if (packet_write_fmt_gently(process->in, "version=%d\n", | |
132 | versions[i])) | |
133 | return error("Could not write requested version"); | |
134 | } | |
135 | if (packet_flush_gently(process->in)) | |
136 | return error("Could not write flush packet"); | |
137 | ||
138 | if (!(line = packet_read_line(process->out, NULL)) || | |
139 | !skip_prefix(line, welcome_prefix, &p) || | |
140 | strcmp(p, "-server")) | |
141 | return error("Unexpected line '%s', expected %s-server", | |
142 | line ? line : "<flush packet>", welcome_prefix); | |
143 | if (!(line = packet_read_line(process->out, NULL)) || | |
144 | !skip_prefix(line, "version=", &p) || | |
145 | strtol_i(p, 10, chosen_version)) | |
146 | return error("Unexpected line '%s', expected version", | |
147 | line ? line : "<flush packet>"); | |
148 | if ((line = packet_read_line(process->out, NULL))) | |
149 | return error("Unexpected line '%s', expected flush", line); | |
150 | ||
151 | /* Check to make sure that the version received is supported */ | |
152 | for (i = 0; versions[i]; i++) { | |
153 | if (versions[i] == *chosen_version) | |
154 | break; | |
155 | } | |
156 | if (!versions[i]) | |
157 | return error("Version %d not supported", *chosen_version); | |
158 | ||
159 | return 0; | |
160 | } | |
161 | ||
162 | static int handshake_capabilities(struct child_process *process, | |
163 | struct subprocess_capability *capabilities, | |
164 | unsigned int *supported_capabilities) | |
165 | { | |
166 | int i; | |
167 | char *line; | |
168 | ||
169 | for (i = 0; capabilities[i].name; i++) { | |
170 | if (packet_write_fmt_gently(process->in, "capability=%s\n", | |
171 | capabilities[i].name)) | |
172 | return error("Could not write requested capability"); | |
173 | } | |
174 | if (packet_flush_gently(process->in)) | |
175 | return error("Could not write flush packet"); | |
176 | ||
177 | while ((line = packet_read_line(process->out, NULL))) { | |
178 | const char *p; | |
179 | if (!skip_prefix(line, "capability=", &p)) | |
180 | continue; | |
181 | ||
182 | for (i = 0; | |
183 | capabilities[i].name && strcmp(p, capabilities[i].name); | |
184 | i++) | |
185 | ; | |
186 | if (capabilities[i].name) { | |
187 | if (supported_capabilities) | |
188 | *supported_capabilities |= capabilities[i].flag; | |
189 | } else { | |
190 | die("subprocess '%s' requested unsupported capability '%s'", | |
191 | process->args.v[0], p); | |
192 | } | |
193 | } | |
194 | ||
195 | return 0; | |
196 | } | |
197 | ||
198 | int subprocess_handshake(struct subprocess_entry *entry, | |
199 | const char *welcome_prefix, | |
200 | int *versions, | |
201 | int *chosen_version, | |
202 | struct subprocess_capability *capabilities, | |
203 | unsigned int *supported_capabilities) | |
204 | { | |
205 | int retval; | |
206 | struct child_process *process = &entry->process; | |
207 | ||
208 | sigchain_push(SIGPIPE, SIG_IGN); | |
209 | ||
210 | retval = handshake_version(process, welcome_prefix, versions, | |
211 | chosen_version) || | |
212 | handshake_capabilities(process, capabilities, | |
213 | supported_capabilities); | |
214 | ||
215 | sigchain_pop(SIGPIPE); | |
216 | return retval; | |
217 | } |