| 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 | int len; |
| 34 | |
| 35 | for (;;) { |
| 36 | char *line; |
| 37 | const char *value; |
| 38 | |
| 39 | len = packet_read_line_gently(fd, NULL, &line); |
| 40 | if ((len < 0) || !line) |
| 41 | break; |
| 42 | if (skip_prefix(line, "status=", &value)) { |
| 43 | /* the last "status=<foo>" line wins */ |
| 44 | strbuf_reset(status); |
| 45 | strbuf_addstr(status, value); |
| 46 | } |
| 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->ent, 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 | strvec_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->ent, 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->ent); |
| 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 (packet_read_line_gently(process->out, NULL, &line) < 0) |
| 136 | return error("could not read greeting from subprocess '%s'", |
| 137 | process->args.v[0]); |
| 138 | if (!line || !skip_prefix(line, welcome_prefix, &p) || |
| 139 | strcmp(p, "-server")) |
| 140 | return error("Unexpected line '%s', expected %s-server", |
| 141 | line ? line : "<flush packet>", welcome_prefix); |
| 142 | if (packet_read_line_gently(process->out, NULL, &line) < 0) |
| 143 | return error("could not read version from subprocess '%s'", |
| 144 | process->args.v[0]); |
| 145 | if (!line || !skip_prefix(line, "version=", &p) || |
| 146 | strtol_i(p, 10, chosen_version)) |
| 147 | return error("Unexpected line '%s', expected version", |
| 148 | line ? line : "<flush packet>"); |
| 149 | if (packet_read_line_gently(process->out, NULL, &line) < 0) |
| 150 | return error("could not read version flush from subprocess '%s'", |
| 151 | process->args.v[0]); |
| 152 | if (line) |
| 153 | return error("Unexpected line '%s', expected flush", line); |
| 154 | |
| 155 | /* Check to make sure that the version received is supported */ |
| 156 | for (i = 0; versions[i]; i++) { |
| 157 | if (versions[i] == *chosen_version) |
| 158 | break; |
| 159 | } |
| 160 | if (!versions[i]) |
| 161 | return error("Version %d not supported", *chosen_version); |
| 162 | |
| 163 | return 0; |
| 164 | } |
| 165 | |
| 166 | static int handshake_capabilities(struct child_process *process, |
| 167 | struct subprocess_capability *capabilities, |
| 168 | unsigned int *supported_capabilities) |
| 169 | { |
| 170 | int i; |
| 171 | char *line; |
| 172 | |
| 173 | for (i = 0; capabilities[i].name; i++) { |
| 174 | if (packet_write_fmt_gently(process->in, "capability=%s\n", |
| 175 | capabilities[i].name)) |
| 176 | return error("Could not write requested capability"); |
| 177 | } |
| 178 | if (packet_flush_gently(process->in)) |
| 179 | return error("Could not write flush packet"); |
| 180 | |
| 181 | for (;;) { |
| 182 | const char *p; |
| 183 | int len = packet_read_line_gently(process->out, NULL, &line); |
| 184 | |
| 185 | if (len < 0) |
| 186 | return error("could not read capabilities from subprocess '%s'", |
| 187 | process->args.v[0]); |
| 188 | if (!line) |
| 189 | break; |
| 190 | if (!skip_prefix(line, "capability=", &p)) |
| 191 | continue; |
| 192 | |
| 193 | for (i = 0; |
| 194 | capabilities[i].name && strcmp(p, capabilities[i].name); |
| 195 | i++) |
| 196 | ; |
| 197 | if (capabilities[i].name) { |
| 198 | if (supported_capabilities) |
| 199 | *supported_capabilities |= capabilities[i].flag; |
| 200 | } else { |
| 201 | die("subprocess '%s' requested unsupported capability '%s'", |
| 202 | process->args.v[0], p); |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | return 0; |
| 207 | } |
| 208 | |
| 209 | int subprocess_handshake(struct subprocess_entry *entry, |
| 210 | const char *welcome_prefix, |
| 211 | int *versions, |
| 212 | int *chosen_version, |
| 213 | struct subprocess_capability *capabilities, |
| 214 | unsigned int *supported_capabilities) |
| 215 | { |
| 216 | int retval; |
| 217 | struct child_process *process = &entry->process; |
| 218 | |
| 219 | sigchain_push(SIGPIPE, SIG_IGN); |
| 220 | |
| 221 | retval = handshake_version(process, welcome_prefix, versions, |
| 222 | chosen_version) || |
| 223 | handshake_capabilities(process, capabilities, |
| 224 | supported_capabilities); |
| 225 | |
| 226 | sigchain_pop(SIGPIPE); |
| 227 | return retval; |
| 228 | } |