pkt.c 8.9 KB
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/*
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 * Copyright (C) 2009-2011 the libgit2 contributors
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 *
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 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
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 */

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#include "common.h"

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#include "git2/types.h"
#include "git2/errors.h"
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#include "git2/refs.h"
#include "git2/revwalk.h"
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#include "pkt.h"
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#include "util.h"
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#include "netops.h"
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#include "posix.h"
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#include "buffer.h"
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#include <ctype.h>

#define PKT_LEN_SIZE 4
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static const char pkt_done_str[] = "0009done\n";
static const char pkt_flush_str[] = "0000";
static const char pkt_have_prefix[] = "0032have ";
static const char pkt_want_prefix[] = "0032want ";
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static int flush_pkt(git_pkt **out)
{
	git_pkt *pkt;

	pkt = git__malloc(sizeof(git_pkt));
	if (pkt == NULL)
		return GIT_ENOMEM;

	pkt->type = GIT_PKT_FLUSH;
	*out = pkt;

	return GIT_SUCCESS;
}

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/* the rest of the line will be useful for multi_ack */
static int ack_pkt(git_pkt **out, const char *GIT_UNUSED(line), size_t GIT_UNUSED(len))
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{
	git_pkt *pkt;
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	GIT_UNUSED_ARG(line);
	GIT_UNUSED_ARG(len);
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	pkt = git__malloc(sizeof(git_pkt));
	if (pkt == NULL)
		return GIT_ENOMEM;

	pkt->type = GIT_PKT_ACK;
	*out = pkt;

	return GIT_SUCCESS;
}

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static int nak_pkt(git_pkt **out)
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{
	git_pkt *pkt;

	pkt = git__malloc(sizeof(git_pkt));
	if (pkt == NULL)
		return GIT_ENOMEM;

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	pkt->type = GIT_PKT_NAK;
	*out = pkt;

	return GIT_SUCCESS;
}

static int pack_pkt(git_pkt **out)
{
	git_pkt *pkt;

	pkt = git__malloc(sizeof(git_pkt));
	if (pkt == NULL)
		return GIT_ENOMEM;

	pkt->type = GIT_PKT_PACK;
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	*out = pkt;

	return GIT_SUCCESS;
}

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static int comment_pkt(git_pkt **out, const char *line, size_t len)
{
	git_pkt_comment *pkt;

	pkt = git__malloc(sizeof(git_pkt_comment) + len + 1);
	if  (pkt == NULL)
		return GIT_ENOMEM;

	pkt->type = GIT_PKT_COMMENT;
	memcpy(pkt->comment, line, len);
	pkt->comment[len] = '\0';

	*out = (git_pkt *) pkt;

	return GIT_SUCCESS;
}

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/*
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 * Parse an other-ref line.
 */
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static int ref_pkt(git_pkt **out, const char *line, size_t len)
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{
	git_pkt_ref *pkt;
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	int error;
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	pkt = git__malloc(sizeof(git_pkt_ref));
	if (pkt == NULL)
		return GIT_ENOMEM;

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	memset(pkt, 0x0, sizeof(git_pkt_ref));
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	pkt->type = GIT_PKT_REF;
	error = git_oid_fromstr(&pkt->head.oid, line);
	if (error < GIT_SUCCESS) {
		error = git__throw(error, "Failed to parse reference ID");
		goto out;
	}

	/* Check for a bit of consistency */
	if (line[GIT_OID_HEXSZ] != ' ') {
		error = git__throw(GIT_EOBJCORRUPTED, "Failed to parse ref. No SP");
		goto out;
	}

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	/* Jump from the name */
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	line += GIT_OID_HEXSZ + 1;
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	len -= (GIT_OID_HEXSZ + 1);
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	if (line[len - 1] == '\n')
		--len;
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	pkt->head.name = git__malloc(len + 1);
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	if (pkt->head.name == NULL) {
		error = GIT_ENOMEM;
		goto out;
	}
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	memcpy(pkt->head.name, line, len);
	pkt->head.name[len] = '\0';
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	if (strlen(pkt->head.name) < len) {
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		pkt->capabilities = strchr(pkt->head.name, '\0') + 1;
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	}

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out:
	if (error < GIT_SUCCESS)
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		git__free(pkt);
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	else
		*out = (git_pkt *)pkt;

	return error;
}

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static ssize_t parse_len(const char *line)
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{
	char num[PKT_LEN_SIZE + 1];
	int i, error;
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	int len;
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	const char *num_end;

	memcpy(num, line, PKT_LEN_SIZE);
	num[PKT_LEN_SIZE] = '\0';

	for (i = 0; i < PKT_LEN_SIZE; ++i) {
		if (!isxdigit(num[i]))
			return GIT_ENOTNUM;
	}

	error = git__strtol32(&len, num, &num_end, 16);
	if (error < GIT_SUCCESS) {
		return error;
	}

	return (unsigned int) len;
}

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/*
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 * As per the documentation, the syntax is:
 *
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 * pkt-line	= data-pkt / flush-pkt
 * data-pkt	= pkt-len pkt-payload
 * pkt-len		= 4*(HEXDIG)
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 * pkt-payload = (pkt-len -4)*(OCTET)
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 * flush-pkt	= "0000"
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 *
 * Which means that the first four bytes are the length of the line,
 * in ASCII hexadecimal (including itself)
 */

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int git_pkt_parse_line(git_pkt **head, const char *line, const char **out, size_t bufflen)
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{
	int error = GIT_SUCCESS;
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	size_t len;
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	/* Not even enough for the length */
	if (bufflen > 0 && bufflen < PKT_LEN_SIZE)
		return GIT_ESHORTBUFFER;
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	error = parse_len(line);
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	if (error < GIT_SUCCESS) {
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		/*
		 * If we fail to parse the length, it might be because the
		 * server is trying to send us the packfile already.
		 */
		if (bufflen >= 4 && !git__prefixcmp(line, "PACK")) {
			*out = line;
			return pack_pkt(head);
		}

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		return git__throw(error, "Failed to parse pkt length");
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	}
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	len = error;

	/*
	 * If we were given a buffer length, then make sure there is
	 * enough in the buffer to satisfy this line
	 */
	if (bufflen > 0 && bufflen < len)
		return GIT_ESHORTBUFFER;

	line += PKT_LEN_SIZE;
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	/*
	 * TODO: How do we deal with empty lines? Try again? with the next
	 * line?
	 */
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	if (len == PKT_LEN_SIZE) {
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		*out = line;
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		return GIT_SUCCESS;
	}

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	if (len == 0) { /* Flush pkt */
		*out = line;
		return flush_pkt(head);
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	}

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	len -= PKT_LEN_SIZE; /* the encoded length includes its own size */
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	/* Assming the minimal size is actually 4 */
	if (!git__prefixcmp(line, "ACK"))
		error = ack_pkt(head, line, len);
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	else if (!git__prefixcmp(line, "NAK"))
		error = nak_pkt(head);
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	else if (*line == '#')
		error = comment_pkt(head, line, len);
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	else
		error = ref_pkt(head, line, len);
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	*out = line + len;

	return error;
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}
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void git_pkt_free(git_pkt *pkt)
{
	if(pkt->type == GIT_PKT_REF) {
		git_pkt_ref *p = (git_pkt_ref *) pkt;
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		git__free(p->head.name);
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	}

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	git__free(pkt);
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}

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int git_pkt_buffer_flush(git_buf *buf)
{
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	git_buf_put(buf, pkt_flush_str, strlen(pkt_flush_str));
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	return git_buf_oom(buf) ? GIT_ENOMEM : GIT_SUCCESS;
}

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int git_pkt_send_flush(int s)
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{

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	return gitno_send(s, pkt_flush_str, strlen(pkt_flush_str), 0);
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}
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static int buffer_want_with_caps(git_remote_head *head, git_transport_caps *caps, git_buf *buf)
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{
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	char capstr[20];
	char oid[GIT_OID_HEXSZ +1] = {0};
	int len;
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	if (caps->ofs_delta)
		strcpy(capstr, GIT_CAP_OFS_DELTA);

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	len = strlen("XXXXwant ") + GIT_OID_HEXSZ + 1 /* NUL */ + strlen(capstr) + 1 /* LF */;
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	git_buf_grow(buf, buf->size + len);
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	git_oid_fmt(oid, &head->oid);
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	git_buf_printf(buf, "%04xwant %s%c%s\n", len, oid, 0, capstr);

	return git_buf_oom(buf) ? GIT_ENOMEM : GIT_SUCCESS;
}

static int send_want_with_caps(git_remote_head *head, git_transport_caps *caps, GIT_SOCKET fd)
{
	git_buf buf = GIT_BUF_INIT;
	int error;

	error = buffer_want_with_caps(head, caps, &buf);
	if (error < GIT_SUCCESS)
		return git__rethrow(error, "Failed to buffer want with caps");

	error = gitno_send(fd, buf.ptr, buf.size, 0);
	git_buf_free(&buf);

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	return error;
}

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/*
 * All "want" packets have the same length and format, so what we do
 * is overwrite the OID each time.
 */

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int git_pkt_buffer_wants(git_headarray *refs, git_transport_caps *caps, git_buf *buf)
{
	unsigned int i = 0;
	int error;
	git_remote_head *head;

	if (caps->common) {
		for (; i < refs->len; ++i) {
			head = refs->heads[i];
			if (!head->local)
				break;
		}

		error = buffer_want_with_caps(refs->heads[i], caps, buf);
		if (error < GIT_SUCCESS)
			return git__rethrow(error, "Failed to buffer want with caps");

		i++;
	}

	for (; i < refs->len; ++i) {
		char oid[GIT_OID_HEXSZ];

		head = refs->heads[i];
		if (head->local)
			continue;

		git_oid_fmt(oid, &head->oid);
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		git_buf_put(buf, pkt_want_prefix, strlen(pkt_want_prefix));
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		git_buf_put(buf, oid, GIT_OID_HEXSZ);
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		git_buf_putc(buf, '\n');
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	}

	return git_pkt_buffer_flush(buf);
}

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int git_pkt_send_wants(git_headarray *refs, git_transport_caps *caps, int fd)
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{
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	unsigned int i = 0;
	int error = GIT_SUCCESS;
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	char buf[sizeof(pkt_want_prefix) + GIT_OID_HEXSZ + 1];
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	git_remote_head *head;

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	memcpy(buf, pkt_want_prefix, strlen(pkt_want_prefix));
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	buf[sizeof(buf) - 2] = '\n';
	buf[sizeof(buf) - 1] = '\0';

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	/* If there are common caps, find the first one */
	if (caps->common) {
		for (; i < refs->len; ++i) {
			head = refs->heads[i];
			if (head->local)
				continue;
			else
				break;
		}

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		error = send_want_with_caps(refs->heads[i], caps, fd);
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		if (error < GIT_SUCCESS)
			return git__rethrow(error, "Failed to send want pkt with caps");
		/* Increase it here so it's correct whether we run this or not */
		i++;
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	}

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	/* Continue from where we left off */
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	for (; i < refs->len; ++i) {
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		head = refs->heads[i];
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		if (head->local)
			continue;
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		git_oid_fmt(buf + strlen(pkt_want_prefix), &head->oid);
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		error = gitno_send(fd, buf, strlen(buf), 0);
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		if (error < GIT_SUCCESS)
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			return git__rethrow(error, "Failed to send want pkt");
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	}

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	return git_pkt_send_flush(fd);
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}

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int git_pkt_buffer_have(git_oid *oid, git_buf *buf)
{
	char oidhex[GIT_OID_HEXSZ + 1];

	memset(oidhex, 0x0, sizeof(oidhex));
	git_oid_fmt(oidhex, oid);
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	git_buf_printf(buf, "%s%s\n", pkt_have_prefix, oidhex);
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	return git_buf_oom(buf) ? GIT_ENOMEM : GIT_SUCCESS;
}

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int git_pkt_send_have(git_oid *oid, int fd)
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{
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	char buf[] = "0032have 0000000000000000000000000000000000000000\n";
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	git_oid_fmt(buf + strlen(pkt_have_prefix), oid);
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	return gitno_send(fd, buf, strlen(buf), 0);
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}
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int git_pkt_buffer_done(git_buf *buf)
{
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	git_buf_puts(buf, pkt_done_str);
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	return git_buf_oom(buf) ? GIT_ENOMEM : GIT_SUCCESS;
}

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int git_pkt_send_done(int fd)
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{
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	return gitno_send(fd, pkt_done_str, strlen(pkt_done_str), 0);
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}