From 3efb988098858bf6b974b1e673a190f9d2965d1d Mon Sep 17 00:00:00 2001 From: Jeff King Date: Thu, 24 Sep 2015 19:12:23 -0400 Subject: react to errors in xdi_diff When we call into xdiff to perform a diff, we generally lose the return code completely. Typically by ignoring the return of our xdi_diff wrapper, but sometimes we even propagate that return value up and then ignore it later. This can lead to us silently producing incorrect diffs (e.g., "git log" might produce no output at all, not even a diff header, for a content-level diff). In practice this does not happen very often, because the typical reason for xdiff to report failure is that it malloc() failed (it uses straight malloc, and not our xmalloc wrapper). But it could also happen when xdiff triggers one our callbacks, which returns an error (e.g., outf() in builtin/rerere.c tries to report a write failure in this way). And the next patch also plans to add more failure modes. Let's notice an error return from xdiff and react appropriately. In most of the diff.c code, we can simply die(), which matches the surrounding code (e.g., that is what we do if we fail to load a file for diffing in the first place). This is not that elegant, but we are probably better off dying to let the user know there was a problem, rather than simply generating bogus output. We could also just die() directly in xdi_diff, but the callers typically have a bit more context, and can provide a better message (and if we do later decide to pass errors up, we're one step closer to doing so). There is one interesting case, which is in diff_grep(). Here if we cannot generate the diff, there is nothing to match, and we silently return "no hits". This is actually what the existing code does already, but we make it a little more explicit. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- line-log.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'line-log.c') diff --git a/line-log.c b/line-log.c index 1a6bc5921..d4e29a574 100644 --- a/line-log.c +++ b/line-log.c @@ -325,7 +325,7 @@ static int collect_diff_cb(long start_a, long count_a, return 0; } -static void collect_diff(mmfile_t *parent, mmfile_t *target, struct diff_ranges *out) +static int collect_diff(mmfile_t *parent, mmfile_t *target, struct diff_ranges *out) { struct collect_diff_cbdata cbdata = {NULL}; xpparam_t xpp; @@ -340,7 +340,7 @@ static void collect_diff(mmfile_t *parent, mmfile_t *target, struct diff_ranges xecfg.hunk_func = collect_diff_cb; memset(&ecb, 0, sizeof(ecb)); ecb.priv = &cbdata; - xdi_diff(parent, target, &xpp, &xecfg, &ecb); + return xdi_diff(parent, target, &xpp, &xecfg, &ecb); } /* @@ -1030,7 +1030,8 @@ static int process_diff_filepair(struct rev_info *rev, } diff_ranges_init(&diff); - collect_diff(&file_parent, &file_target, &diff); + if (collect_diff(&file_parent, &file_target, &diff)) + die("unable to generate diff for %s", pair->one->path); /* NEEDSWORK should apply some heuristics to prevent mismatches */ free(rg->path); -- cgit v1.2.1