upload-archive: fix infinite loop on Cygwin

On Cygwin, poll() reports POLLIN even for file descriptors that have
reached their end.  This caused git upload-archive to be stuck in an
infinite loop, as it only looked at the POLLIN flag.

In addition to POLLIN, check if read() returned 0, which indicates
end-of-file, and keep looping only as long as at least one of the file
descriptors has input.  This lets the following command finish on its
own when run in a git repository on Cygwin, instead of it getting stuck
after printing all file names:

	$ git archive -v --remote . HEAD >/dev/null

Reported-by: Bob Kagy <bobkagy@gmail.com>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-upload-archive.c b/builtin-upload-archive.c
index a9b02fa32f372a6810867c10560a20d58b5b2a91..f6c4c0f149801c2d423f7ed1740a6fe9b03cf8df 100644 (file)
--- a/builtin-upload-archive.c
+++ b/builtin-upload-archive.c
@@ -80,16 +80,17 @@ static void error_clnt(const char *fmt, ...)
        die("sent error to the client: %s", buf);
 }
 
-static void process_input(int child_fd, int band)
+static ssize_t process_input(int child_fd, int band)
 {
        char buf[16384];
        ssize_t sz = read(child_fd, buf, sizeof(buf));
        if (sz < 0) {
                if (errno != EAGAIN && errno != EINTR)
                        error_clnt("read error: %s\n", strerror(errno));
-               return;
+               return sz;
        }
        send_sideband(1, band, buf, sz, LARGE_PACKET_MAX);
+       return sz;
 }
 
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
@@ -131,6 +132,7 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 
        while (1) {
                struct pollfd pfd[2];
+               ssize_t processed[2] = { 0, 0 };
                int status;
 
                pfd[0].fd = fd1[0];
@@ -147,12 +149,12 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
                }
                if (pfd[0].revents & POLLIN)
                        /* Data stream ready */
-                       process_input(pfd[0].fd, 1);
+                       processed[0] = process_input(pfd[0].fd, 1);
                if (pfd[1].revents & POLLIN)
                        /* Status stream ready */
-                       process_input(pfd[1].fd, 2);
+                       processed[1] = process_input(pfd[1].fd, 2);
                /* Always finish to read data when available */
-               if ((pfd[0].revents | pfd[1].revents) & POLLIN)
+               if (processed[0] || processed[1])
                        continue;
 
                if (waitpid(writer, &status, 0) < 0)