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-rw-r--r--builtin/get-tar-commit-id.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
new file mode 100644
index 0000000..20d0dfe
--- /dev/null
+++ b/builtin/get-tar-commit-id.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2005, 2006 Rene Scharfe
+ */
+#include "builtin.h"
+#include "commit.h"
+#include "tar.h"
+#include "quote.h"
+
+static const char builtin_get_tar_commit_id_usage[] =
+"git get-tar-commit-id";
+
+/* ustar header + extended global header content */
+#define RECORDSIZE (512)
+#define HEADERSIZE (2 * RECORDSIZE)
+
+int cmd_get_tar_commit_id(int argc, const char **argv UNUSED, const char *prefix)
+{
+ char buffer[HEADERSIZE];
+ struct ustar_header *header = (struct ustar_header *)buffer;
+ char *content = buffer + RECORDSIZE;
+ const char *comment;
+ ssize_t n;
+ long len;
+ char *end;
+
+ BUG_ON_NON_EMPTY_PREFIX(prefix);
+
+ if (argc != 1)
+ usage(builtin_get_tar_commit_id_usage);
+
+ n = read_in_full(0, buffer, HEADERSIZE);
+ if (n < 0)
+ die_errno("git get-tar-commit-id: read error");
+ if (n != HEADERSIZE)
+ die_errno("git get-tar-commit-id: EOF before reading tar header");
+ if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
+ return 1;
+
+ len = strtol(content, &end, 10);
+ if (errno == ERANGE || end == content || len < 0)
+ return 1;
+ if (!skip_prefix(end, " comment=", &comment))
+ return 1;
+ len -= comment - content;
+ if (len < 1 || !(len % 2) ||
+ hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
+ return 1;
+
+ if (write_in_full(1, comment, len) < 0)
+ die_errno("git get-tar-commit-id: write error");
+
+ return 0;
+}