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authorMichael Haggerty <mhagger@alum.mit.edu>2018-01-24 11:14:11 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-01-24 20:55:26 (GMT)
commit4a2854f77cc913fafc7f3191a61b343280979643 (patch)
tree57d604f72493ca03e6da89f7bb15f90b773012b3
parent3013dff8662eae06457fe6e5348dfe2270810ab2 (diff)
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struct snapshot: store `start` rather than `header_len`
Store a pointer to the start of the actual references within the `packed-refs` contents rather than storing the length of the header. This is more convenient for most users of this field. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--refs/packed-backend.c64
1 files changed, 33 insertions, 31 deletions
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index dab8a85..26b8901 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -68,17 +68,21 @@ struct snapshot {
int mmapped;
/*
- * The contents of the `packed-refs` file. If the file was
- * already sorted, this points at the mmapped contents of the
- * file. If not, this points at heap-allocated memory
- * containing the contents, sorted. If there were no contents
- * (e.g., because the file didn't exist), `buf` and `eof` are
- * both NULL.
+ * The contents of the `packed-refs` file:
+ *
+ * - buf -- a pointer to the start of the memory
+ * - start -- a pointer to the first byte of actual references
+ * (i.e., after the header line, if one is present)
+ * - eof -- a pointer just past the end of the reference
+ * contents
+ *
+ * If the `packed-refs` file was already sorted, `buf` points
+ * at the mmapped contents of the file. If not, it points at
+ * heap-allocated memory containing the contents, sorted. If
+ * there were no contents (e.g., because the file didn't
+ * exist), `buf`, `start`, and `eof` are all NULL.
*/
- char *buf, *eof;
-
- /* The size of the header line, if any; otherwise, 0: */
- size_t header_len;
+ char *buf, *start, *eof;
/*
* What is the peeled state of the `packed-refs` file that
@@ -169,8 +173,7 @@ static void clear_snapshot_buffer(struct snapshot *snapshot)
} else {
free(snapshot->buf);
}
- snapshot->buf = snapshot->eof = NULL;
- snapshot->header_len = 0;
+ snapshot->buf = snapshot->start = snapshot->eof = NULL;
}
/*
@@ -319,13 +322,14 @@ static void sort_snapshot(struct snapshot *snapshot)
size_t len, i;
char *new_buffer, *dst;
- pos = snapshot->buf + snapshot->header_len;
+ pos = snapshot->start;
eof = snapshot->eof;
- len = eof - pos;
- if (!len)
+ if (pos == eof)
return;
+ len = eof - pos;
+
/*
* Initialize records based on a crude estimate of the number
* of references in the file (we'll grow it below if needed):
@@ -391,9 +395,8 @@ static void sort_snapshot(struct snapshot *snapshot)
* place:
*/
clear_snapshot_buffer(snapshot);
- snapshot->buf = new_buffer;
+ snapshot->buf = snapshot->start = new_buffer;
snapshot->eof = new_buffer + len;
- snapshot->header_len = 0;
cleanup:
free(records);
@@ -442,14 +445,14 @@ static const char *find_end_of_record(const char *p, const char *end)
*/
static void verify_buffer_safe(struct snapshot *snapshot)
{
- const char *buf = snapshot->buf + snapshot->header_len;
+ const char *start = snapshot->start;
const char *eof = snapshot->eof;
const char *last_line;
- if (buf == eof)
+ if (start == eof)
return;
- last_line = find_start_of_record(buf, eof - 1);
+ last_line = find_start_of_record(start, eof - 1);
if (*(eof - 1) != '\n' || eof - last_line < GIT_SHA1_HEXSZ + 2)
die_invalid_line(snapshot->refs->path,
last_line, eof - last_line);
@@ -495,18 +498,19 @@ static int load_contents(struct snapshot *snapshot)
bytes_read = read_in_full(fd, snapshot->buf, size);
if (bytes_read < 0 || bytes_read != size)
die_errno("couldn't read %s", snapshot->refs->path);
- snapshot->eof = snapshot->buf + size;
snapshot->mmapped = 0;
break;
case MMAP_TEMPORARY:
case MMAP_OK:
snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
- snapshot->eof = snapshot->buf + size;
snapshot->mmapped = 1;
break;
}
close(fd);
+ snapshot->start = snapshot->buf;
+ snapshot->eof = snapshot->buf + size;
+
return 1;
}
@@ -539,7 +543,7 @@ static const char *find_reference_location(struct snapshot *snapshot,
* preceding records all have reference names that come
* *before* `refname`.
*/
- const char *lo = snapshot->buf + snapshot->header_len;
+ const char *lo = snapshot->start;
/*
* A pointer to a the first character of a record whose
@@ -617,8 +621,7 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
/* If the file has a header line, process it: */
if (snapshot->buf < snapshot->eof && *snapshot->buf == '#') {
struct strbuf tmp = STRBUF_INIT;
- char *p;
- const char *eol;
+ char *p, *eol;
struct string_list traits = STRING_LIST_INIT_NODUP;
eol = memchr(snapshot->buf, '\n',
@@ -647,7 +650,7 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
/* perhaps other traits later as well */
/* The "+ 1" is for the LF character. */
- snapshot->header_len = eol + 1 - snapshot->buf;
+ snapshot->start = eol + 1;
string_list_clear(&traits, 0);
strbuf_release(&tmp);
@@ -671,13 +674,12 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
* We don't want to leave the file mmapped, so we are
* forced to make a copy now:
*/
- size_t size = snapshot->eof -
- (snapshot->buf + snapshot->header_len);
+ size_t size = snapshot->eof - snapshot->start;
char *buf_copy = xmalloc(size);
- memcpy(buf_copy, snapshot->buf + snapshot->header_len, size);
+ memcpy(buf_copy, snapshot->start, size);
clear_snapshot_buffer(snapshot);
- snapshot->buf = buf_copy;
+ snapshot->buf = snapshot->start = buf_copy;
snapshot->eof = buf_copy + size;
}
@@ -937,7 +939,7 @@ static struct ref_iterator *packed_ref_iterator_begin(
if (prefix && *prefix)
start = find_reference_location(snapshot, prefix, 0);
else
- start = snapshot->buf + snapshot->header_len;
+ start = snapshot->start;
iter->pos = start;
iter->eof = snapshot->eof;