Support delimited data regions in fast-import.

During testing its nice to not have to feed the length of a data
chunk to the 'data' command of fast-import.  Instead we would
prefer to be able to establish a data chunk much like shell's <<
operator and use a line delimiter to denote the end of the input.

So now if a data command is started as 'data <<EOF' we will look
for a terminator line containing only the string EOF on that line.
Once found, we stop the data command.  Everything between the two
lines is used as the data value.

The 'data <<' syntax is slower than 'data n', as we don't know how
many bytes to expect and instead must grow our buffer on the fly.
It also has the problem that the frontend must use a string which
will not appear on a line by itself in the input, and the data
region will always end in an LF.  For these reasons real import
frontends are encouraged to continue to use _only_ 'data n'.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/fast-import.c b/fast-import.c
index 9a642f2e02e4a695b0aa37c660e965362e68f297..90adc680421540202aeca556c4223c72a3ea9b7a 100644 (file)
--- a/fast-import.c
+++ b/fast-import.c
@@ -50,14 +50,21 @@ Format of STDIN stream:
      # a new mark directive with the old idnum.
         #
   mark ::= 'mark' sp idnum lf;
+  data ::= (delimited_data | exact_data)
+    lf;
+
+    # note: delim may be any string but must not contain lf.
+    # data_line may contain any data but must not be exactly
+    # delim.
+  delimited_data ::= 'data' sp '<<' delim lf
+    (data_line lf)*
+       delim lf;
 
      # note: declen indicates the length of binary_data in bytes.
-     # declen does not include the lf preceeding or trailing the
-     # binary data.
+     # declen does not include the lf preceeding the binary data.
      #
-  data ::= 'data' sp declen lf
-    binary_data
-       lf;
+  exact_data ::= 'data' sp declen lf
+    binary_data;
 
      # note: quoted strings are C-style quoting supporting \c for
      # common escapes of 'c' (e..g \n, \t, \\, \") or \nnn where nnn
@@ -1334,21 +1341,48 @@ static void cmd_mark(void)
 
 static void* cmd_data (size_t *size)
 {
-       size_t n = 0;
-       void *buffer;
        size_t length;
+       char *buffer;
 
        if (strncmp("data ", command_buf.buf, 5))
                die("Expected 'data n' command, found: %s", command_buf.buf);
 
-       length = strtoul(command_buf.buf + 5, NULL, 10);
-       buffer = xmalloc(length);
-
-       while (n < length) {
-               size_t s = fread((char*)buffer + n, 1, length - n, stdin);
-               if (!s && feof(stdin))
-                       die("EOF in data (%lu bytes remaining)", length - n);
-               n += s;
+       if (!strncmp("<<", command_buf.buf + 5, 2)) {
+               char *term = xstrdup(command_buf.buf + 5 + 2);
+               size_t sz = 8192, term_len = command_buf.len - 5 - 2;
+               length = 0;
+               buffer = xmalloc(sz);
+               for (;;) {
+                       read_next_command();
+                       if (command_buf.eof)
+                               die("EOF in data (terminator '%s' not found)", term);
+                       if (term_len == command_buf.len
+                               && !strcmp(term, command_buf.buf))
+                               break;
+                       if (sz < (length + command_buf.len)) {
+                               sz = sz * 3 / 2 + 16;
+                               if (sz < (length + command_buf.len))
+                                       sz = length + command_buf.len;
+                               buffer = xrealloc(buffer, sz);
+                       }
+                       memcpy(buffer + length,
+                               command_buf.buf,
+                               command_buf.len - 1);
+                       length += command_buf.len - 1;
+                       buffer[length++] = '\n';
+               }
+               free(term);
+       }
+       else {
+               size_t n = 0;
+               length = strtoul(command_buf.buf + 5, NULL, 10);
+               buffer = xmalloc(length);
+               while (n < length) {
+                       size_t s = fread(buffer + n, 1, length - n, stdin);
+                       if (!s && feof(stdin))
+                               die("EOF in data (%lu bytes remaining)", length - n);
+                       n += s;
+               }
        }
 
        if (fgetc(stdin) != '\n')