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![Jeff King](/assets/img/avatar_default.png)
The packets sent during ref negotiation are all terminated by newline; even though the code to chomp these newlines is short, we end up doing it in a lot of places. This patch teaches packet_read_line to auto-chomp the trailing newline; this lets us get rid of a lot of inline chomping code. As a result, some call-sites which are not reading line-oriented data (e.g., when reading chunks of packfiles alongside sideband) transition away from packet_read_line to the generic packet_read interface. This patch converts all of the existing callsites. Since the function signature of packet_read_line does not change (but its behavior does), there is a possibility of new callsites being introduced in later commits, silently introducing an incompatibility. However, since a later patch in this series will change the signature, such a commit would have to be merged directly into this commit, not to the tip of the series; we can therefore ignore the issue. This is an internal cleanup and should produce no change of behavior in the normal case. However, there is one corner case to note. Callers of packet_read_line have never been able to tell the difference between a flush packet ("0000") and an empty packet ("0004"), as both cause packet_read_line to return a length of 0. Readers treat them identically, even though Documentation/technical/protocol-common.txt says we must not; it also says that implementations should not send an empty pkt-line. By stripping out the newline before the result gets to the caller, we will now treat the newline-only packet ("0005\n") the same as an empty packet, which in turn gets treated like a flush packet. In practice this doesn't matter, as neither empty nor newline-only packets are part of git's protocols (at least not for the line-oriented bits, and readers who are not expecting line-oriented packets will be calling packet_read directly, anyway). But even if we do decide to care about the distinction later, it is orthogonal to this patch. The right place to tighten would be to stop treating empty packets as flush packets, and this change does not make doing so any harder. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
211 lines
4 KiB
C
211 lines
4 KiB
C
#include "cache.h"
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#include "pkt-line.h"
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static const char *packet_trace_prefix = "git";
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static const char trace_key[] = "GIT_TRACE_PACKET";
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void packet_trace_identity(const char *prog)
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{
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packet_trace_prefix = xstrdup(prog);
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}
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static void packet_trace(const char *buf, unsigned int len, int write)
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{
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int i;
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struct strbuf out;
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if (!trace_want(trace_key))
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return;
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/* +32 is just a guess for header + quoting */
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strbuf_init(&out, len+32);
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strbuf_addf(&out, "packet: %12s%c ",
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packet_trace_prefix, write ? '>' : '<');
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if ((len >= 4 && !prefixcmp(buf, "PACK")) ||
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(len >= 5 && !prefixcmp(buf+1, "PACK"))) {
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strbuf_addstr(&out, "PACK ...");
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unsetenv(trace_key);
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}
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else {
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/* XXX we should really handle printable utf8 */
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for (i = 0; i < len; i++) {
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/* suppress newlines */
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if (buf[i] == '\n')
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continue;
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if (buf[i] >= 0x20 && buf[i] <= 0x7e)
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strbuf_addch(&out, buf[i]);
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else
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strbuf_addf(&out, "\\%o", buf[i]);
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}
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}
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strbuf_addch(&out, '\n');
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trace_strbuf(trace_key, &out);
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strbuf_release(&out);
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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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packet_trace("0000", 4, 1);
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write_or_die(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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packet_trace("0000", 4, 1);
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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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packet_trace(buffer+4, n-4, 1);
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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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write_or_die(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 int safe_read(int fd, void *buffer, unsigned size, int options)
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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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if (options & PACKET_READ_GENTLE_ON_EOF)
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return -1;
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die("The remote end hung up unexpectedly");
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}
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return ret;
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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(int fd, char *buffer, unsigned size, int options)
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{
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int len, ret;
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char linelen[4];
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ret = safe_read(fd, linelen, 4, options);
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if (ret < 0)
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return ret;
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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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packet_trace("0000", 4, 0);
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return 0;
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}
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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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ret = safe_read(fd, buffer, len, options);
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if (ret < 0)
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return ret;
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if ((options & PACKET_READ_CHOMP_NEWLINE) &&
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len && buffer[len-1] == '\n')
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len--;
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buffer[len] = 0;
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packet_trace(buffer, len, 0);
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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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return packet_read(fd, buffer, size, PACKET_READ_CHOMP_NEWLINE);
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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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packet_trace("0000", 4, 0);
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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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packet_trace(out->buf, out->len, 0);
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return len;
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}
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