[PATCH] Add --path-prefix option to git-fast-import

[Gisle Aas <gisle.aas@it.uib.no>]

From: Gisle Aas <gisle@aas.no>

I found this useful when import multiple external repositories to be merged
into a single git repo.  Not having the files be renamed during the merge
made it easier to follow the history of the individual files.

Signed-off-by: Gisle Aas <gisle@aas.no>
---
 Documentation/git-fast-import.txt |    6 ++++++
 fast-import.c                     |   24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 288032c..b8f9593 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -58,6 +58,12 @@ OPTIONS
 	Maximum number of branches to maintain active at once.
 	See ``Memory Utilization'' below for details.  Default is 5.
 
+--path-prefix=<str>:
+	Prepend the given prefix to all the paths imported.
+	This can be used to import stuff into a subdirectory
+	of where the original files where located.  Most likely
+	you want <str> to end with a slash.
+
 --export-marks=<file>::
 	Dumps the internal marks table to <file> when complete.
 	Marks are written one per line as `:markid SHA-1`.
diff --git a/fast-import.c b/fast-import.c
index dd3c99d..32b0d70 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -351,6 +351,8 @@ static struct recent_command *rc_free;
 static unsigned int cmd_save = 100;
 static uintmax_t next_mark;
 static struct strbuf new_data = STRBUF_INIT;
+static const char *path_prefix;
+static size_t path_prefix_len;
 
 static void write_branch_report(FILE *rpt, struct branch *b)
 {
@@ -1860,6 +1862,16 @@ static void load_branch(struct branch *b)
 	}
 }
 
+static const char *path_prefix_prepend(struct strbuf *sb, const char *p)
+{
+	if (p != sb->buf) {
+	    strbuf_reset(sb);
+	    strbuf_addstr(sb, p);
+	}
+	strbuf_insert(sb, 0, path_prefix, path_prefix_len);
+	return sb->buf;
+}
+
 static void file_change_m(struct branch *b)
 {
 	const char *p = command_buf.buf + 2;
@@ -1909,6 +1921,8 @@ static void file_change_m(struct branch *b)
 			die("Garbage after path in: %s", command_buf.buf);
 		p = uq.buf;
 	}
+	if (path_prefix)
+	    p = path_prefix_prepend(&uq, p);
 
 	if (S_ISGITLINK(mode)) {
 		if (inline_data)
@@ -1961,6 +1975,8 @@ static void file_change_d(struct branch *b)
 			die("Garbage after path in: %s", command_buf.buf);
 		p = uq.buf;
 	}
+	if (path_prefix)
+	    p = path_prefix_prepend(&uq, p);
 	tree_content_remove(&b->branch_tree, p, NULL);
 }
 
@@ -1984,6 +2000,8 @@ static void file_change_cr(struct branch *b, int rename)
 		strbuf_add(&s_uq, s, endp - s);
 	}
 	s = s_uq.buf;
+	if (path_prefix)
+	    s = path_prefix_prepend(&s_uq, s);
 
 	endp++;
 	if (!*endp)
@@ -1996,6 +2014,8 @@ static void file_change_cr(struct branch *b, int rename)
 			die("Garbage after dest in: %s", command_buf.buf);
 		d = d_uq.buf;
 	}
+	if (path_prefix)
+	    d = path_prefix_prepend(&d_uq, d);
 
 	memset(&leaf, 0, sizeof(leaf));
 	if (rename)
@@ -2523,6 +2543,10 @@ int main(int argc, const char **argv)
 			if (max_depth > MAX_DEPTH)
 				die("--depth cannot exceed %u", MAX_DEPTH);
 		}
+		else if (!prefixcmp(a, "--path-prefix=")) {
+			path_prefix = a + 14;
+			path_prefix_len = strlen(path_prefix);
+		}
 		else if (!prefixcmp(a, "--active-branches="))
 			max_active_branches = strtoul(a + 18, NULL, 0);
 		else if (!prefixcmp(a, "--import-marks="))
-- 
1.6.6.rc4.12.g269e7