Racy git: avoid having to be always too careful

diff --git a/fetch-clone.c b/fetch-clone.c
index da1b3ffbaa13ee4dfc8d080759b3f936850b7647..5e84c4620ff96f5c7ab93e5f3bfd10609edd5fd5 100644 (file)
--- a/fetch-clone.c
+++ b/fetch-clone.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "exec_cmd.h"
+#include "pkt-line.h"
 #include <sys/wait.h>
 #include <sys/time.h>
 
@@ -23,7 +24,7 @@ static int finish_pack(const char *pack_tmp_name, const char *me)
 
        pid = fork();
        if (pid < 0)
-               die("git-clone-pack: unable to fork off git-index-pack");
+               die("%s: unable to fork off git-index-pack", me);
        if (!pid) {
                close(0);
                dup2(pipe_fd[1], 1);
@@ -94,11 +95,71 @@ static int finish_pack(const char *pack_tmp_name, const char *me)
        exit(1);
 }
 
-int receive_unpack_pack(int fd[2], const char *me, int quiet)
+static pid_t setup_sideband(int sideband, const char *me, int fd[2], int xd[2])
+{
+       pid_t side_pid;
+
+       if (!sideband) {
+               fd[0] = xd[0];
+               fd[1] = xd[1];
+               return 0;
+       }
+       /* xd[] is talking with upload-pack; subprocess reads from
+        * xd[0], spits out band#2 to stderr, and feeds us band#1
+        * through our fd[0].
+        */
+       if (pipe(fd) < 0)
+               die("%s: unable to set up pipe", me);
+       side_pid = fork();
+       if (side_pid < 0)
+               die("%s: unable to fork off sideband demultiplexer", me);
+       if (!side_pid) {
+               /* subprocess */
+               close(fd[0]);
+               if (xd[0] != xd[1])
+                       close(xd[1]);
+               while (1) {
+                       char buf[1024];
+                       int len = packet_read_line(xd[0], buf, sizeof(buf));
+                       if (len == 0)
+                               break;
+                       if (len < 1)
+                               die("%s: protocol error: no band designator",
+                                   me);
+                       len--;
+                       switch (buf[0] & 0xFF) {
+                       case 3:
+                               safe_write(2, "remote: ", 8);
+                               safe_write(2, buf+1, len);
+                               safe_write(2, "\n", 1);
+                               exit(1);
+                       case 2:
+                               safe_write(2, "remote: ", 8);
+                               safe_write(2, buf+1, len);
+                               continue;
+                       case 1:
+                               safe_write(fd[1], buf+1, len);
+                               continue;
+                       default:
+                               die("%s: protocol error: bad band #%d",
+                                   me, (buf[0] & 0xFF));
+                       }
+               }
+               exit(0);
+       }
+       close(xd[0]);
+       close(fd[1]);
+       fd[1] = xd[1];
+       return side_pid;
+}
+
+int receive_unpack_pack(int xd[2], const char *me, int quiet, int sideband)
 {
        int status;
-       pid_t pid;
+       pid_t pid, side_pid;
+       int fd[2];
 
+       side_pid = setup_sideband(sideband, me, fd, xd);
        pid = fork();
        if (pid < 0)
                die("%s: unable to fork off git-unpack-objects", me);
@@ -139,18 +200,18 @@ int receive_unpack_pack(int fd[2], const char *me, int quiet)
 
 /*
  * A "binary msec" is a power-of-two-msec, aka 1/1024th of a second.
- * Keeing the time in that format means that "bytes / msecs" means
- * is the same as kB/s (modulo rounding).
+ * Keeping the time in that format means that "bytes / msecs" means
+ * the same as kB/s (modulo rounding).
  *
  * 1000512 is a magic number (usecs in a second, rounded up by half
  * of 1024, to make "rounding" come out right ;)
  */
 #define usec_to_binarymsec(x) ((int)(x) / (1000512 >> 10))
 
-int receive_keep_pack(int fd[2], const char *me, int quiet)
+int receive_keep_pack(int xd[2], const char *me, int quiet, int sideband)
 {
        char tmpfile[PATH_MAX];
-       int ofd, ifd;
+       int ofd, ifd, fd[2];
        unsigned long total;
        static struct timeval prev_tv;
        struct average {
@@ -160,6 +221,8 @@ int receive_keep_pack(int fd[2], const char *me, int quiet)
        unsigned long avg_bytes, avg_time;
        int idx = 0;
 
+       setup_sideband(sideband, me, fd, xd);
+
        ifd = fd[0];
        snprintf(tmpfile, sizeof(tmpfile),
                 "%s/pack/tmp-XXXXXX", get_object_directory());