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pkt-line: add functions to read/write flush terminated packet streams 

write_packetized_from_fd() and write_packetized_from_buf() write a
stream of packets. All content packets use the maximal packet size
except for the last one. After the last content packet a `flush` control
packet is written.

read_packetized_to_strbuf() reads arbitrary sized packets until it
detects a `flush` packet.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Lars Schneider 2016-10-16 16:20:34 -07:00 committed by Junio C Hamano
parent edfb780cd4
commit bb643d8bf8
2 changed files with 80 additions and 0 deletions
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72
pkt-line.c
View File

@ -197,6 +197,46 @@ void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
va_end(args);
}

int write_packetized_from_fd(int fd_in, int fd_out)
{
static char buf[LARGE_PACKET_DATA_MAX];
int err = 0;
ssize_t bytes_to_write;

while (!err) {
bytes_to_write = xread(fd_in, buf, sizeof(buf));
if (bytes_to_write < 0)
return COPY_READ_ERROR;
if (bytes_to_write == 0)
break;
err = packet_write_gently(fd_out, buf, bytes_to_write);
}
if (!err)
err = packet_flush_gently(fd_out);
return err;
}

int write_packetized_from_buf(const char *src_in, size_t len, int fd_out)
{
int err = 0;
size_t bytes_written = 0;
size_t bytes_to_write;

while (!err) {
if ((len - bytes_written) > LARGE_PACKET_DATA_MAX)
bytes_to_write = LARGE_PACKET_DATA_MAX;
else
bytes_to_write = len - bytes_written;
if (bytes_to_write == 0)
break;
err = packet_write_gently(fd_out, src_in + bytes_written, bytes_to_write);
bytes_written += bytes_to_write;
}
if (!err)
err = packet_flush_gently(fd_out);
return err;
}

static int get_packet_data(int fd, char **src_buf, size_t *src_size,
void *dst, unsigned size, int options)
{
@ -287,3 +327,35 @@ char *packet_read_line_buf(char **src, size_t *src_len, int *dst_len)
{
return packet_read_line_generic(-1, src, src_len, dst_len);
}

ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out)
{
int packet_len;

size_t orig_len = sb_out->len;
size_t orig_alloc = sb_out->alloc;

for (;;) {
strbuf_grow(sb_out, LARGE_PACKET_DATA_MAX);
packet_len = packet_read(fd_in, NULL, NULL,
/* strbuf_grow() above always allocates one extra byte to
* store a '\0' at the end of the string. packet_read()
* writes a '\0' extra byte at the end, too. Let it know
* that there is already room for the extra byte.
*/
sb_out->buf + sb_out->len, LARGE_PACKET_DATA_MAX+1,
PACKET_READ_GENTLE_ON_EOF);
if (packet_len <= 0)
break;
sb_out->len += packet_len;
}

if (packet_len < 0) {
if (orig_alloc == 0)
strbuf_release(sb_out);
else
strbuf_setlen(sb_out, orig_len);
return packet_len;
}
return sb_out->len - orig_len;
}

8
pkt-line.h
View File

@ -25,6 +25,8 @@ void packet_buf_flush(struct strbuf *buf);
void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
int packet_flush_gently(int fd);
int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
int write_packetized_from_fd(int fd_in, int fd_out);
int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);

/*
* Read a packetized line into the buffer, which must be at least size bytes
@ -77,8 +79,14 @@ char *packet_read_line(int fd, int *size);
*/
char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);

/*
* Reads a stream of variable sized packets until a flush packet is detected.
*/
ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);

#define DEFAULT_PACKET_MAX 1000
#define LARGE_PACKET_MAX 65520
#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
extern char packet_buffer[LARGE_PACKET_MAX];

#endif