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