t6022: New tests checking for unnecessary updates of files

diff --git a/pkt-line.c b/pkt-line.c
index 295ba2b16c8675d8c5c5d0a5ee6e61e044ce99dd..5a04984ea31744528de30269add2754ed2dcd105 100644 (file)
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -1,6 +1,51 @@
 #include "cache.h"
 #include "pkt-line.h"
 
+static const char *packet_trace_prefix = "git";
+static const char trace_key[] = "GIT_TRACE_PACKET";
+
+void packet_trace_identity(const char *prog)
+{
+       packet_trace_prefix = xstrdup(prog);
+}
+
+static void packet_trace(const char *buf, unsigned int len, int write)
+{
+       int i;
+       struct strbuf out;
+
+       if (!trace_want(trace_key))
+               return;
+
+       /* +32 is just a guess for header + quoting */
+       strbuf_init(&out, len+32);
+
+       strbuf_addf(&out, "packet: %12s%c ",
+                   packet_trace_prefix, write ? '>' : '<');
+
+       if ((len >= 4 && !prefixcmp(buf, "PACK")) ||
+           (len >= 5 && !prefixcmp(buf+1, "PACK"))) {
+               strbuf_addstr(&out, "PACK ...");
+               unsetenv(trace_key);
+       }
+       else {
+               /* XXX we should really handle printable utf8 */
+               for (i = 0; i < len; i++) {
+                       /* suppress newlines */
+                       if (buf[i] == '\n')
+                               continue;
+                       if (buf[i] >= 0x20 && buf[i] <= 0x7e)
+                               strbuf_addch(&out, buf[i]);
+                       else
+                               strbuf_addf(&out, "\\%o", buf[i]);
+               }
+       }
+
+       strbuf_addch(&out, '\n');
+       trace_strbuf(trace_key, &out);
+       strbuf_release(&out);
+}
+
 /*
  * Write a packetized stream, where each line is preceded by
  * its length (including the header) as a 4-byte hex number.
@@ -39,11 +84,13 @@ ssize_t safe_write(int fd, const void *buf, ssize_t n)
  */
 void packet_flush(int fd)
 {
+       packet_trace("0000", 4, 1);
        safe_write(fd, "0000", 4);
 }
 
 void packet_buf_flush(struct strbuf *buf)
 {
+       packet_trace("0000", 4, 1);
        strbuf_add(buf, "0000", 4);
 }
 
@@ -62,6 +109,7 @@ static unsigned format_packet(const char *fmt, va_list args)
        buffer[1] = hex(n >> 8);
        buffer[2] = hex(n >> 4);
        buffer[3] = hex(n);
+       packet_trace(buffer+4, n-4, 1);
        return n;
 }
 
@@ -130,13 +178,16 @@ int packet_read_line(int fd, char *buffer, unsigned size)
        len = packet_length(linelen);
        if (len < 0)
                die("protocol error: bad line length character: %.4s", linelen);
-       if (!len)
+       if (!len) {
+               packet_trace("0000", 4, 0);
                return 0;
+       }
        len -= 4;
        if (len >= size)
                die("protocol error: bad line length %d", len);
        safe_read(fd, buffer, len);
        buffer[len] = 0;
+       packet_trace(buffer, len, 0);
        return len;
 }
 
@@ -153,6 +204,7 @@ int packet_get_line(struct strbuf *out,
        if (!len) {
                *src_buf += 4;
                *src_len -= 4;
+               packet_trace("0000", 4, 0);
                return 0;
        }
        if (*src_len < len)
@@ -165,5 +217,6 @@ int packet_get_line(struct strbuf *out,
        strbuf_add(out, *src_buf, len);
        *src_buf += len;
        *src_len -= len;
+       packet_trace(out->buf, out->len, 0);
        return len;
 }