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         const char *argv[] = { cmd, NULL };
  81
  82         entry->cmd = cmd;
  83         process = &entry->process;
  84
  85         child_process_init(process);
  86         process->argv = argv;
  87         process->use_shell = 1;
  88         process->in = -1;
  89         process->out = -1;
  90         process->clean_on_exit = 1;
  91         process->clean_on_exit_handler = subprocess_exit_handler;
  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 }