[PATCH] Make git status print a helpful death message if the disk is full

The old behavior just said that it failed.  Now it includes the error
information, which makes it much easier to debug.

There is a risk that some failure paths could result in misleading error
messages that actually make debugging more difficult.

Signed-off-by: David Reiss <redacted>
---
 builtin-commit.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/builtin-commit.c b/builtin-commit.c
index 4bcce06..3527c73 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c

@@ -256,7 +256,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
 		refresh_cache(REFRESH_QUIET);
 		if (write_cache(fd, active_cache, active_nr) ||
 		    close_lock_file(&index_lock))
-			die("unable to write new_index file");
+			die("unable to write new_index file: %s", strerror(errno));
 		commit_style = COMMIT_NORMAL;
 		return index_lock.filename;
 	}

@@ -275,7 +275,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
 		refresh_cache(REFRESH_QUIET);
 		if (write_cache(fd, active_cache, active_nr) ||
 		    commit_locked_index(&index_lock))
-			die("unable to write new_index file");
+			die("unable to write new_index file: %s", strerror(errno));
 		commit_style = COMMIT_AS_IS;
 		return get_index_file();
 	}

@@ -318,7 +318,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
 	refresh_cache(REFRESH_QUIET);
 	if (write_cache(fd, active_cache, active_nr) ||
 	    close_lock_file(&index_lock))
-		die("unable to write new_index file");
+		die("unable to write new_index file: %s", strerror(errno));
 
 	fd = hold_lock_file_for_update(&false_lock,
 				       git_path("next-index-%"PRIuMAX,

-- 
1.6.0.4

David Reiss wrote:

The old behavior just said that it failed.  Now it includes the error
information, which makes it much easier to debug.

There is a risk that some failure paths could result in misleading error
messages that actually make debugging more difficult.

[...]

 		if (write_cache(fd, active_cache, active_nr) ||
 		    close_lock_file(&index_lock))
-			die("unable to write new_index file");
+			die("unable to write new_index file: %s", strerror(errno));

Junio C Hamano wrote:

Don't we have die_errno() or something since at least 1.6.4?

Yes.  And during the conversion, I ignored call sites like this one
precisely because I did not (and still do not) have enough knowledge
of the index and lock file machinery to decide at what stage I need to
read errno to get the *real* error message.  You're of course welcome
to dig into the code to verify that the above is correct, but I am
against blindly hoping that it gives the right error.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch