unix-socket.c

   1 #define DISABLE_SIGN_COMPARE_WARNINGS
   2
   3 #include "git-compat-util.h"
   4 #include "strbuf.h"
   5 #include "unix-socket.h"
   6
   7 #define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)
   8
   9 static int chdir_len(const char *orig, int len)
  10 {
  11         char *path = xmemdupz(orig, len);
  12         int r = chdir(path);
  13         free(path);
  14         return r;
  15 }
  16
  17 struct unix_sockaddr_context {
  18         char *orig_dir;
  19 };
  20
  21 static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)
  22 {
  23         if (!ctx->orig_dir)
  24                 return;
  25         /*
  26          * If we fail, we can't just return an error, since we have
  27          * moved the cwd of the whole process, which could confuse calling
  28          * code.  We are better off to just die.
  29          */
  30         if (chdir(ctx->orig_dir) < 0)
  31                 die("unable to restore original working directory");
  32         free(ctx->orig_dir);
  33 }
  34
  35 static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
  36                               struct unix_sockaddr_context *ctx,
  37                               int disallow_chdir)
  38 {
  39         int size = strlen(path) + 1;
  40
  41         ctx->orig_dir = NULL;
  42         if (size > sizeof(sa->sun_path)) {
  43                 const char *slash;
  44                 const char *dir;
  45                 struct strbuf cwd = STRBUF_INIT;
  46
  47                 if (disallow_chdir) {
  48                         errno = ENAMETOOLONG;
  49                         return -1;
  50                 }
  51
  52                 slash = find_last_dir_sep(path);
  53                 if (!slash) {
  54                         errno = ENAMETOOLONG;
  55                         return -1;
  56                 }
  57
  58                 dir = path;
  59                 path = slash + 1;
  60                 size = strlen(path) + 1;
  61                 if (size > sizeof(sa->sun_path)) {
  62                         errno = ENAMETOOLONG;
  63                         return -1;
  64                 }
  65                 if (strbuf_getcwd(&cwd))
  66                         return -1;
  67                 ctx->orig_dir = strbuf_detach(&cwd, NULL);
  68                 if (chdir_len(dir, slash - dir) < 0) {
  69                         FREE_AND_NULL(ctx->orig_dir);
  70                         return -1;
  71                 }
  72         }
  73
  74         memset(sa, 0, sizeof(*sa));
  75         sa->sun_family = AF_UNIX;
  76         memcpy(sa->sun_path, path, size);
  77         return 0;
  78 }
  79
  80 int unix_stream_connect(const char *path, int disallow_chdir)
  81 {
  82         int fd = -1, saved_errno;
  83         struct sockaddr_un sa;
  84         struct unix_sockaddr_context ctx;
  85
  86         if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0)
  87                 return -1;
  88         fd = socket(AF_UNIX, SOCK_STREAM, 0);
  89         if (fd < 0)
  90                 goto fail;
  91
  92         if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
  93                 goto fail;
  94         unix_sockaddr_cleanup(&ctx);
  95         return fd;
  96
  97 fail:
  98         saved_errno = errno;
  99         if (fd != -1)
 100                 close(fd);
 101         unix_sockaddr_cleanup(&ctx);
 102         errno = saved_errno;
 103         return -1;
 104 }
 105
 106 int unix_stream_listen(const char *path,
 107                        const struct unix_stream_listen_opts *opts)
 108 {
 109         int fd = -1, saved_errno;
 110         int backlog;
 111         struct sockaddr_un sa;
 112         struct unix_sockaddr_context ctx;
 113
 114         unlink(path);
 115
 116         if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0)
 117                 return -1;
 118         fd = socket(AF_UNIX, SOCK_STREAM, 0);
 119         if (fd < 0)
 120                 goto fail;
 121
 122         if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
 123                 goto fail;
 124
 125         backlog = opts->listen_backlog_size;
 126         if (backlog <= 0)
 127                 backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;
 128         if (listen(fd, backlog) < 0)
 129                 goto fail;
 130
 131         unix_sockaddr_cleanup(&ctx);
 132         return fd;
 133
 134 fail:
 135         saved_errno = errno;
 136         if (fd != -1)
 137                 close(fd);
 138         unix_sockaddr_cleanup(&ctx);
 139         errno = saved_errno;
 140         return -1;
 141 }