unix-socket.c

   1 #include "cache.h"
   2 #include "unix-socket.h"
   3
   4 static int unix_stream_socket(void)
   5 {
   6         int fd = socket(AF_UNIX, SOCK_STREAM, 0);
   7         if (fd < 0)
   8                 die_errno("unable to create socket");
   9         return fd;
  10 }
  11
  12 static int chdir_len(const char *orig, int len)
  13 {
  14         char *path = xmemdupz(orig, len);
  15         int r = chdir(path);
  16         free(path);
  17         return r;
  18 }
  19
  20 struct unix_sockaddr_context {
  21         char orig_dir[PATH_MAX];
  22 };
  23
  24 static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)
  25 {
  26         if (!ctx->orig_dir[0])
  27                 return;
  28         /*
  29          * If we fail, we can't just return an error, since we have
  30          * moved the cwd of the whole process, which could confuse calling
  31          * code.  We are better off to just die.
  32          */
  33         if (chdir(ctx->orig_dir) < 0)
  34                 die("unable to restore original working directory");
  35 }
  36
  37 static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
  38                               struct unix_sockaddr_context *ctx)
  39 {
  40         int size = strlen(path) + 1;
  41
  42         ctx->orig_dir[0] = '\0';
  43         if (size > sizeof(sa->sun_path)) {
  44                 const char *slash = find_last_dir_sep(path);
  45                 const char *dir;
  46
  47                 if (!slash) {
  48                         errno = ENAMETOOLONG;
  49                         return -1;
  50                 }
  51
  52                 dir = path;
  53                 path = slash + 1;
  54                 size = strlen(path) + 1;
  55                 if (size > sizeof(sa->sun_path)) {
  56                         errno = ENAMETOOLONG;
  57                         return -1;
  58                 }
  59
  60                 if (!getcwd(ctx->orig_dir, sizeof(ctx->orig_dir))) {
  61                         errno = ENAMETOOLONG;
  62                         return -1;
  63                 }
  64                 if (chdir_len(dir, slash - dir) < 0)
  65                         return -1;
  66         }
  67
  68         memset(sa, 0, sizeof(*sa));
  69         sa->sun_family = AF_UNIX;
  70         memcpy(sa->sun_path, path, size);
  71         return 0;
  72 }
  73
  74 int unix_stream_connect(const char *path)
  75 {
  76         int fd, saved_errno;
  77         struct sockaddr_un sa;
  78         struct unix_sockaddr_context ctx;
  79
  80         if (unix_sockaddr_init(&sa, path, &ctx) < 0)
  81                 return -1;
  82         fd = unix_stream_socket();
  83         if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
  84                 goto fail;
  85         unix_sockaddr_cleanup(&ctx);
  86         return fd;
  87
  88 fail:
  89         saved_errno = errno;
  90         unix_sockaddr_cleanup(&ctx);
  91         close(fd);
  92         errno = saved_errno;
  93         return -1;
  94 }
  95
  96 int unix_stream_listen(const char *path)
  97 {
  98         int fd, saved_errno;
  99         struct sockaddr_un sa;
 100         struct unix_sockaddr_context ctx;
 101
 102         if (unix_sockaddr_init(&sa, path, &ctx) < 0)
 103                 return -1;
 104         fd = unix_stream_socket();
 105
 106         unlink(path);
 107         if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
 108                 goto fail;
 109
 110         if (listen(fd, 5) < 0)
 111                 goto fail;
 112
 113         unix_sockaddr_cleanup(&ctx);
 114         return fd;
 115
 116 fail:
 117         saved_errno = errno;
 118         unix_sockaddr_cleanup(&ctx);
 119         close(fd);
 120         errno = saved_errno;
 121         return -1;
 122 }