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![Shawn O. Pearce](/assets/img/avatar_default.png)
When there is an error parsing the 4 byte length component we now display it as part of the die message, this may hint as to what data was misunderstood by the application. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
170 lines
3.3 KiB
C
170 lines
3.3 KiB
C
#include "cache.h"
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#include "pkt-line.h"
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/*
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* Write a packetized stream, where each line is preceded by
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* its length (including the header) as a 4-byte hex number.
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* A length of 'zero' means end of stream (and a length of 1-3
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* would be an error).
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*
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* This is all pretty stupid, but we use this packetized line
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* format to make a streaming format possible without ever
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* over-running the read buffers. That way we'll never read
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* into what might be the pack data (which should go to another
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* process entirely).
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*
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* The writing side could use stdio, but since the reading
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* side can't, we stay with pure read/write interfaces.
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*/
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ssize_t safe_write(int fd, const void *buf, ssize_t n)
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{
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ssize_t nn = n;
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while (n) {
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int ret = xwrite(fd, buf, n);
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if (ret > 0) {
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buf = (char *) buf + ret;
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n -= ret;
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continue;
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}
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if (!ret)
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die("write error (disk full?)");
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die_errno("write error");
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}
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return nn;
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}
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/*
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* If we buffered things up above (we don't, but we should),
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* we'd flush it here
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*/
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void packet_flush(int fd)
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{
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safe_write(fd, "0000", 4);
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}
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void packet_buf_flush(struct strbuf *buf)
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{
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strbuf_add(buf, "0000", 4);
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}
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#define hex(a) (hexchar[(a) & 15])
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static char buffer[1000];
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static unsigned format_packet(const char *fmt, va_list args)
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{
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static char hexchar[] = "0123456789abcdef";
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unsigned n;
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n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
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if (n >= sizeof(buffer)-4)
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die("protocol error: impossibly long line");
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n += 4;
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buffer[0] = hex(n >> 12);
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buffer[1] = hex(n >> 8);
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buffer[2] = hex(n >> 4);
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buffer[3] = hex(n);
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return n;
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}
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void packet_write(int fd, const char *fmt, ...)
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{
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va_list args;
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unsigned n;
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va_start(args, fmt);
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n = format_packet(fmt, args);
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va_end(args);
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safe_write(fd, buffer, n);
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}
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void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
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{
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va_list args;
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unsigned n;
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va_start(args, fmt);
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n = format_packet(fmt, args);
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va_end(args);
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strbuf_add(buf, buffer, n);
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}
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static void safe_read(int fd, void *buffer, unsigned size)
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{
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ssize_t ret = read_in_full(fd, buffer, size);
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if (ret < 0)
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die_errno("read error");
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else if (ret < size)
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die("The remote end hung up unexpectedly");
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}
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static int packet_length(const char *linelen)
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{
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int n;
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int len = 0;
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for (n = 0; n < 4; n++) {
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unsigned char c = linelen[n];
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len <<= 4;
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if (c >= '0' && c <= '9') {
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len += c - '0';
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continue;
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}
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if (c >= 'a' && c <= 'f') {
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len += c - 'a' + 10;
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continue;
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}
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if (c >= 'A' && c <= 'F') {
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len += c - 'A' + 10;
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continue;
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}
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return -1;
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}
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return len;
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}
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int packet_read_line(int fd, char *buffer, unsigned size)
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{
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int len;
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char linelen[4];
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safe_read(fd, linelen, 4);
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len = packet_length(linelen);
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if (len < 0)
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die("protocol error: bad line length character: %.4s", linelen);
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if (!len)
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return 0;
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len -= 4;
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if (len >= size)
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die("protocol error: bad line length %d", len);
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safe_read(fd, buffer, len);
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buffer[len] = 0;
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return len;
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}
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int packet_get_line(struct strbuf *out,
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char **src_buf, size_t *src_len)
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{
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int len;
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if (*src_len < 4)
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return -1;
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len = packet_length(*src_buf);
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if (len < 0)
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return -1;
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if (!len) {
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*src_buf += 4;
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*src_len -= 4;
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return 0;
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}
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if (*src_len < len)
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return -2;
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*src_buf += 4;
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*src_len -= 4;
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len -= 4;
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strbuf_add(out, *src_buf, len);
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*src_buf += len;
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*src_len -= len;
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return len;
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}
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