Re: [PATCH] git-rev-list: give better diagnostic for failed write

Jim Meyering [off-list ref] wrote:

[this patch depends on the one I posted here:
 http://marc.info/?l=git&m=118280134031923&w=2 ]

Here's a version of that patch that retains the fflush call
and adds a comment explaining why it's needed.

Without this patch, git-rev-list unnecessarily omits strerror(errno)
from its diagnostic, upon write failure:

    $ ./git-rev-list --max-count=1 HEAD > /dev/full
    fatal: write failure on standard output

With the patch, git reports the desired ENOSPC diagnostic:

    fatal: write failure on standard output: No space left on device

* builtin-rev-list (show_commit): Diagnose a failed fflush call.

Signed-off-by: Jim Meyering <redacted>
---
 builtin-rev-list.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index 813aadf..f13a594 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c

@@ -100,7 +100,12 @@ static void show_commit(struct commit *commit)
 		printf("%s%c", buf, hdr_termination);
 		free(buf);
 	}
-	fflush(stdout);
+
+	/* Flush regularly.
+	   This is especially important for an asynchronous consumer.  */
+	if (fflush(stdout))
+		die("write failure on standard output: %s", strerror(errno));
+
 	if (commit->parents) {
 		free_commit_list(commit->parents);
 		commit->parents = NULL;