[PATCH 03/17] Introduce $GIT_DIR/narrow

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

This file contains a sorted list of narrow prefix, used in narrow
repositories.

rev-parse also learns --narrow-prefix to print $GIT_DIR/narrow out

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-rev-parse.txt        |    3 +
 Documentation/gitrepository-layout.txt |    5 ++
 Makefile                               |    2 +
 builtin/rev-parse.c                    |    8 +++
 cache.h                                |    3 +
 environment.c                          |    2 +
 narrow-tree.c                          |  106 ++++++++++++++++++++++++++++++++
 narrow-tree.h                          |    3 +
 t/t0063-narrow-repo.sh                 |   46 ++++++++++++++
 9 files changed, 178 insertions(+), 0 deletions(-)
 create mode 100644 narrow-tree.c
 create mode 100644 narrow-tree.h
 create mode 100755 t/t0063-narrow-repo.sh

diff --git a/Documentation/git-rev-parse.txt b/Documentation/git-rev-parse.txt
index be4c053..5d5e77b 100644
--- a/Documentation/git-rev-parse.txt
+++ b/Documentation/git-rev-parse.txt
@@ -148,6 +148,9 @@ shown.  If the pattern does not contain a globbing character (`?`,
 --is-bare-repository::
 	When the repository is bare print "true", otherwise "false".
 
+--narrow-prefix::
+	Print narrow prefix git reads from $GIT_DIR/narrow.
+
 --local-env-vars::
 	List the GIT_* environment variables that are local to the
 	repository (e.g. GIT_DIR or GIT_WORK_TREE, but not GIT_EDITOR).
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index eb3d040..82e0350 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -193,6 +193,11 @@ shallow::
 	and maintained by shallow clone mechanism.  See `--depth`
 	option to linkgit:git-clone[1] and linkgit:git-fetch[1].
 
+narrow::
+	This file contains narrow prefix in sorted order. It is
+	internally used and maintained by narrow clone mechanism.
+	See `--narrow-tree` option to linkgit:git-clone[1].
+
 SEE ALSO
 --------
 linkgit:git-init[1],
diff --git a/Makefile b/Makefile
index b4745a5..f1aaba9 100644
--- a/Makefile
+++ b/Makefile
@@ -525,6 +525,7 @@ LIB_H += sigchain.h
 LIB_H += strbuf.h
 LIB_H += string-list.h
 LIB_H += submodule.h
+LIB_H += narrow-tree.h
 LIB_H += tag.h
 LIB_H += transport.h
 LIB_H += tree.h
@@ -629,6 +630,7 @@ LIB_OBJS += sigchain.o
 LIB_OBJS += strbuf.o
 LIB_OBJS += string-list.o
 LIB_OBJS += submodule.o
+LIB_OBJS += narrow-tree.o
 LIB_OBJS += symlinks.o
 LIB_OBJS += tag.o
 LIB_OBJS += trace.o
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index a5a1c86..590df6f 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -675,6 +675,14 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 						: "false");
 				continue;
 			}
+			if (!strcmp(arg, "--narrow-prefix")) {
+				const char **p = get_narrow_prefix();
+				if (!p)
+					continue;
+				while (*p)
+					printf("%s\n", *p++);
+				continue;
+			}
 			if (!prefixcmp(arg, "--since=")) {
 				show_datestring("--max-age=", arg+8);
 				continue;
diff --git a/cache.h b/cache.h
index eb77e1d..d09c4fc 100644
--- a/cache.h
+++ b/cache.h
@@ -1105,4 +1105,7 @@ const char *split_cmdline_strerror(int cmdline_errno);
 /* builtin/merge.c */
 int checkout_fast_forward(const unsigned char *from, const unsigned char *to);
 
+/* narrow-tree.c */
+extern const char **get_narrow_prefix();
+
 #endif /* CACHE_H */
diff --git a/environment.c b/environment.c
index 83d38d3..41fcbd4 100644
--- a/environment.c
+++ b/environment.c
@@ -8,6 +8,7 @@
  * are.
  */
 #include "cache.h"
+#include "narrow-tree.h"
 
 char git_default_email[MAX_GITNAME];
 char git_default_name[MAX_GITNAME];
@@ -105,6 +106,7 @@ static void setup_git_env(void)
 		git_graft_file = git_pathdup("info/grafts");
 	if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
 		read_replace_refs = 0;
+	check_narrow_prefix();
 }
 
 int is_bare_repository(void)
diff --git a/narrow-tree.c b/narrow-tree.c
new file mode 100644
index 0000000..85dbab4
--- /dev/null
+++ b/narrow-tree.c
@@ -0,0 +1,106 @@
+#include "cache.h"
+#include "narrow-tree.h"
+
+static const char **narrow_prefix;
+static char *narrow_buf;
+
+int valid_narrow_prefix(const char *prefix, const char *prev_prefix, int quiet)
+{
+	int len = strlen(prefix);
+
+	if (!*prefix) {
+		if (!quiet)
+			error("Empty line in $GIT_DIR/narrow");
+		return 0;
+	}
+
+	if (prefix[len-1] == '/') {
+		if (!quiet)
+			error("Trailing slash not allowed in $GIT_DIR: %s", prefix);
+		return 0;
+	}
+
+	if (prev_prefix) {
+		if (strcmp(prev_prefix, prefix) >= 0) {
+			if (!quiet)
+				error("$GIT_DIR/narrow is unsorted at %s", prefix);
+			return 0;
+		}
+		len = strlen(prev_prefix);
+		if (!strncmp(prev_prefix, prefix, len) &&
+		    prefix[len] == '/') {
+			if (!quiet) {
+				error("$GIT_DIR/narrow has nested prefix (%s and %s)",
+				      prev_prefix, prefix);
+				return 0;
+			}
+		}
+	}
+	return 1;
+}
+
+int check_narrow_prefix()
+{
+	struct stat st;
+	int fd, i, n, len;
+	char *p, *pp;
+
+	if (stat(git_path("narrow"), &st) || st.st_size == 0)
+		return 0;
+
+	narrow_buf = xmalloc(st.st_size+2); /* NULL and \n */
+
+	fd = open(git_path("narrow"), O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	if (xread(fd, narrow_buf, st.st_size) != st.st_size)
+		die("failed to read $GIT_DIR/narrow");
+	close(fd);
+
+	if (narrow_buf[st.st_size-1] == '\n')
+		narrow_buf[st.st_size] = '\0';
+	else {
+		narrow_buf[st.st_size] = '\n';
+		narrow_buf[st.st_size+1] = '\0';
+	}
+	n = 0;
+	for (p = narrow_buf; *p; p = strchr(p, '\n')+1)
+		n++;
+	if (!n)
+		return 0;
+	narrow_prefix = xmalloc(sizeof(*narrow_prefix)*(n+1));
+	p = narrow_buf;
+	for (i = 0; i < n; i++) {
+		pp = p;
+		p = strchr(p, '\n') + 1;
+		len = p - pp;
+		while (len &&
+		       (pp[len-1] == '\n' ||
+			pp[len-1] == '\r'))
+			len--;
+		pp[len] = '\0';
+		if (!valid_narrow_prefix(pp, i ? narrow_prefix[i-1] : NULL, 0))
+			die("Invalid $GIT_DIR/narrow");
+		narrow_prefix[i] = pp;
+	}
+	narrow_prefix[n] = NULL;
+	return 0;
+}
+
+const char **get_narrow_prefix()
+{
+	return narrow_prefix;
+}
+
+char *get_narrow_string()
+{
+	struct strbuf sb = STRBUF_INIT;
+	const char **prefix = get_narrow_prefix();
+	while (*prefix) {
+		strbuf_addstr(&sb, *prefix);
+		strbuf_addch(&sb, '\n');
+		prefix++;
+	}
+	return strbuf_detach(&sb, NULL);
+}
diff --git a/narrow-tree.h b/narrow-tree.h
new file mode 100644
index 0000000..2097436
--- /dev/null
+++ b/narrow-tree.h
@@ -0,0 +1,3 @@
+extern int valid_narrow_prefix(const char *prefix, const char *prev_prefix, int quiet);
+extern int check_narrow_prefix();
+extern char *get_narrow_string();
diff --git a/t/t0063-narrow-repo.sh b/t/t0063-narrow-repo.sh
new file mode 100755
index 0000000..51b753d
--- /dev/null
+++ b/t/t0063-narrow-repo.sh
@@ -0,0 +1,46 @@
+#!/bin/sh
+
+test_description='narrow index'
+
+. ./test-lib.sh
+
+test_expect_success 'empty $GIT_DIR/narrow' '
+	: >.git/narrow &&
+	git rev-parse --narrow-prefix >result &&
+	: >expected
+	test_cmp expected result
+'
+
+test_expect_success 'empty line' '
+	echo >.git/narrow &&
+	test_must_fail git rev-parse --narrow-prefix
+'
+
+test_expect_success 'single prefix' '
+	echo a >.git/narrow &&
+	git rev-parse --narrow-prefix >result &&
+	echo a >expected
+	test_cmp expected result
+'
+
+test_expect_success 'trailing slash in prefix' '
+	echo a/ >.git/narrow &&
+	test_must_fail git rev-parse --narrow-prefix
+'
+
+test_expect_success 'sorted multiple prefix' '
+	echo a >.git/narrow &&
+	echo b >>.git/narrow &&
+	git rev-parse --narrow-prefix >result &&
+	echo a >expected
+	echo b >>expected
+	test_cmp expected result
+'
+
+test_expect_success 'unsorted multiple prefix' '
+	echo b >.git/narrow &&
+	echo a >>.git/narrow &&
+	test_must_fail git rev-parse --narrow-prefix
+'
+
+test_done
-- 
1.7.1.rc1.69.g24c2f7