[PATCH 3/7] ll-merge: add API for capturing warnings in a strbuf instead of stderr

["Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>]

From: Elijah Newren <newren@gmail.com>

Whenever ll-merge encounters a binary file, it prints a warning to
stderr.  However, for the --remerge-diff option we want to add, we need
to capture all conflict messages and show them in a diff instead of
dumping them straight to stdout or stderr.  Add some new API that will
allow us to capture this output and display it in our preferred method.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 ll-merge.c | 51 +++++++++++++++++++++++++++++++++++++++------------
 ll-merge.h |  9 +++++++++
 2 files changed, 48 insertions(+), 12 deletions(-)

diff --git a/ll-merge.c b/ll-merge.c
index 261657578c7..4d5bdc12464 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -11,11 +11,13 @@
 #include "run-command.h"
 #include "ll-merge.h"
 #include "quote.h"
+#include "strbuf.h"
 
 struct ll_merge_driver;
 
 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 			   mmbuffer_t *result,
+			   struct strbuf *warnings,
 			   const char *path,
 			   mmfile_t *orig, const char *orig_name,
 			   mmfile_t *src1, const char *name1,
@@ -51,6 +53,7 @@ void reset_merge_attributes(void)
  */
 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   mmbuffer_t *result,
+			   struct strbuf *warnings,
 			   const char *path,
 			   mmfile_t *orig, const char *orig_name,
 			   mmfile_t *src1, const char *name1,
@@ -59,6 +62,7 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   int marker_size)
 {
 	mmfile_t *stolen;
+	const char *msg = "Cannot merge binary files: %s (%s vs. %s)";
 	assert(opts);
 
 	/*
@@ -71,8 +75,11 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 	} else {
 		switch (opts->variant) {
 		default:
-			warning("Cannot merge binary files: %s (%s vs. %s)",
-				path, name1, name2);
+			if (warnings) {
+				strbuf_addstr(warnings, "Warning: ");
+				strbuf_addf(warnings, msg, path, name1, name2);
+			} else
+				warning(msg, path, name1, name2);
 			/* fallthru */
 		case XDL_MERGE_FAVOR_OURS:
 			stolen = src1;
@@ -98,6 +105,7 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 
 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 			mmbuffer_t *result,
+			struct strbuf *warnings,
 			const char *path,
 			mmfile_t *orig, const char *orig_name,
 			mmfile_t *src1, const char *name1,
@@ -114,7 +122,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 	    buffer_is_binary(orig->ptr, orig->size) ||
 	    buffer_is_binary(src1->ptr, src1->size) ||
 	    buffer_is_binary(src2->ptr, src2->size)) {
-		return ll_binary_merge(drv_unused, result,
+		return ll_binary_merge(drv_unused, result, warnings,
 				       path,
 				       orig, orig_name,
 				       src1, name1,
@@ -138,6 +146,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 
 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 			  mmbuffer_t *result,
+			  struct strbuf *warnings,
 			  const char *path,
 			  mmfile_t *orig, const char *orig_name,
 			  mmfile_t *src1, const char *name1,
@@ -150,7 +159,7 @@ static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 	assert(opts);
 	o = *opts;
 	o.variant = XDL_MERGE_FAVOR_UNION;
-	return ll_xdl_merge(drv_unused, result, path,
+	return ll_xdl_merge(drv_unused, result, warnings, path,
 			    orig, orig_name, src1, name1, src2, name2,
 			    &o, marker_size);
 }
@@ -180,6 +189,7 @@ static void create_temp(mmfile_t *src, char *path, size_t len)
  */
 static int ll_ext_merge(const struct ll_merge_driver *fn,
 			mmbuffer_t *result,
+			struct strbuf *warnings,
 			const char *path,
 			mmfile_t *orig, const char *orig_name,
 			mmfile_t *src1, const char *name1,
@@ -362,13 +372,14 @@ static void normalize_file(mmfile_t *mm, const char *path, struct index_state *i
 	}
 }
 
-int ll_merge(mmbuffer_t *result_buf,
-	     const char *path,
-	     mmfile_t *ancestor, const char *ancestor_label,
-	     mmfile_t *ours, const char *our_label,
-	     mmfile_t *theirs, const char *their_label,
-	     struct index_state *istate,
-	     const struct ll_merge_options *opts)
+int ll_merge_with_warnings(mmbuffer_t *result_buf,
+			   struct strbuf *warnings,
+			   const char *path,
+			   mmfile_t *ancestor, const char *ancestor_label,
+			   mmfile_t *ours, const char *our_label,
+			   mmfile_t *theirs, const char *their_label,
+			   struct index_state *istate,
+			   const struct ll_merge_options *opts)
 {
 	struct attr_check *check = load_merge_attributes();
 	static const struct ll_merge_options default_opts;
@@ -401,11 +412,27 @@ int ll_merge(mmbuffer_t *result_buf,
 	if (opts->extra_marker_size) {
 		marker_size += opts->extra_marker_size;
 	}
-	return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
+	return driver->fn(driver, result_buf, warnings, path,
+			  ancestor, ancestor_label,
 			  ours, our_label, theirs, their_label,
 			  opts, marker_size);
 }
 
+int ll_merge(mmbuffer_t *result_buf,
+	     const char *path,
+	     mmfile_t *ancestor, const char *ancestor_label,
+	     mmfile_t *ours, const char *our_label,
+	     mmfile_t *theirs, const char *their_label,
+	     struct index_state *istate,
+	     const struct ll_merge_options *opts)
+{
+	return ll_merge_with_warnings(result_buf, NULL, path,
+				      ancestor, ancestor_label,
+				      ours, our_label,
+				      theirs, their_label,
+				      istate, opts);
+}
+
 int ll_merge_marker_size(struct index_state *istate, const char *path)
 {
 	static struct attr_check *check;
diff --git a/ll-merge.h b/ll-merge.h
index aceb1b24132..a5469918ad4 100644
--- a/ll-merge.h
+++ b/ll-merge.h
@@ -96,6 +96,15 @@ int ll_merge(mmbuffer_t *result_buf,
 	     struct index_state *istate,
 	     const struct ll_merge_options *opts);
 
+int ll_merge_with_warnings(mmbuffer_t *result_buf,
+			   struct strbuf *warnings,
+			   const char *path,
+			   mmfile_t *ancestor, const char *ancestor_label,
+			   mmfile_t *ours, const char *our_label,
+			   mmfile_t *theirs, const char *their_label,
+			   struct index_state *istate,
+			   const struct ll_merge_options *opts);
+
 int ll_merge_marker_size(struct index_state *istate, const char *path);
 void reset_merge_attributes(void);
 
-- 
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