[PATCH 08/12] dir.c: keep track of where patterns came from

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

From: Adam Spiers <git@adamspiers.org>

For exclude patterns read in from files, the filename is stored together
with the corresponding line number (counting starting at 1).

For exclude patterns provided on the command line, the sequence number
is negative, with counting starting at -1, so for example the 2nd
pattern provided via --exclude would be numbered -2.  This allows any
future consumers of that data to easily distinguish between exclude
patterns from files vs. from the CLI.

Signed-off-by: Adam Spiers <git@adamspiers.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/clean.c    |  2 +-
 builtin/ls-files.c |  3 ++-
 dir.c              | 26 ++++++++++++++++++++------
 dir.h              |  5 ++++-
 4 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/builtin/clean.c b/builtin/clean.c
index 0c7b3d0..f618231 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -99,7 +99,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 
 	for (i = 0; i < exclude_list.nr; i++)
 		add_exclude(exclude_list.items[i].string, "", 0,
-			    &dir.exclude_list[EXC_CMDL]);
+			    &dir.exclude_list[EXC_CMDL], "--exclude option", -(i+1));
 
 	pathspec = get_pathspec(prefix, argv);
 
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index ef7f99a..db3c081 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -35,6 +35,7 @@ static int error_unmatch;
 static char *ps_matched;
 static const char *with_tree;
 static int exc_given;
+static int exclude_args;
 
 static const char *tag_cached = "";
 static const char *tag_unmerged = "";
@@ -423,7 +424,7 @@ static int option_parse_exclude(const struct option *opt,
 	struct exclude_list *list = opt->value;
 
 	exc_given = 1;
-	add_exclude(arg, "", 0, list);
+	add_exclude(arg, "", 0, list, "--exclude option", --exclude_args);
 
 	return 0;
 }
diff --git a/dir.c b/dir.c
index 84ab826..81a5dd5 100644
--- a/dir.c
+++ b/dir.c
@@ -347,7 +347,8 @@ void parse_exclude_pattern(const char **pattern,
 }
 
 void add_exclude(const char *string, const char *base,
-		 int baselen, struct exclude_list *el)
+		 int baselen, struct exclude_list *el,
+		 const char *src, int srcpos)
 {
 	struct exclude *x;
 	int patternlen;
@@ -371,6 +372,8 @@ void add_exclude(const char *string, const char *base,
 	x->base = base;
 	x->baselen = baselen;
 	x->flags = flags;
+	x->src = src;
+	x->srcpos = srcpos;
 	ALLOC_GROW(el->excludes, el->nr + 1, el->alloc);
 	el->excludes[el->nr++] = x;
 }
@@ -418,7 +421,7 @@ int add_excludes_from_file_to_list(const char *fname,
 				   int check_index)
 {
 	struct stat st;
-	int fd, i;
+	int fd, i, lineno = 1;
 	size_t size = 0;
 	char *buf, *entry;
 
@@ -461,8 +464,10 @@ int add_excludes_from_file_to_list(const char *fname,
 		if (buf[i] == '\n') {
 			if (entry != buf + i && entry[0] != '#') {
 				buf[i - (i && buf[i-1] == '\r')] = 0;
-				add_exclude(entry, base, baselen, el);
+				add_exclude(entry, base, baselen, el,
+					    fname, lineno);
 			}
+			lineno++;
 			entry = buf + i + 1;
 		}
 	}
@@ -493,8 +498,10 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
 		    !strncmp(dir->basebuf, base, stk->baselen))
 			break;
 		dir->exclude_stack = stk->prev;
-		while (stk->exclude_ix < el->nr)
-			free(el->excludes[--el->nr]);
+		while (stk->exclude_ix < el->nr) {
+			struct exclude *exclude = el->excludes[--el->nr];
+			free(exclude);
+		}
 		free(stk->filebuf);
 		free(stk);
 	}
@@ -521,7 +528,14 @@ static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
 		memcpy(dir->basebuf + current, base + current,
 		       stk->baselen - current);
 		strcpy(dir->basebuf + stk->baselen, dir->exclude_per_dir);
-		add_excludes_from_file_to_list(dir->basebuf,
+
+		/*
+		 * dir->basebuf gets reused by the traversal, but we
+		 * need fname to remain unchanged to ensure the src
+		 * member of each struct exclude correctly back-references
+		 * its source file.
+		 */
+		add_excludes_from_file_to_list(strdup(dir->basebuf),
 					       dir->basebuf, stk->baselen,
 					       &stk->filebuf, el, 1);
 		dir->exclude_stack = stk;
diff --git a/dir.h b/dir.h
index 02ac0bf..3921aa9 100644
--- a/dir.h
+++ b/dir.h
@@ -23,6 +23,9 @@ struct exclude_list {
 		const char *base;
 		int baselen;
 		int flags;
+		const char *src;
+		int srcpos; /* counting starts from 1 for line numbers in ignore files,
+			       and from -1 decrementing for patterns from CLI (--exclude) */
 	} **excludes;
 };
 
@@ -112,7 +115,7 @@ extern int add_excludes_from_file_to_list(const char *fname, const char *base, i
 extern void add_excludes_from_file(struct dir_struct *, const char *fname);
 extern void parse_exclude_pattern(const char **string, int *patternlen, int *flags, int *nowildcardlen);
 extern void add_exclude(const char *string, const char *base,
-			int baselen, struct exclude_list *el);
+			int baselen, struct exclude_list *el, const char *src, int srcpos);
 extern void free_excludes(struct exclude_list *el);
 extern int file_exists(const char *);
 
-- 
1.8.0.rc0.29.g1fdd78f