buffer_read_binary is a thin wrapper around fread, but its signature
is wrong:
- fread can fill an arbitrary in-memory buffer. buffer_read_binary
is limited to buffers whose size is representable by a 32-bit
integer.
- The result from fread is the number of bytes actually read.
buffer_read_binary only reports the number of bytes read by
incrementing sb->len by that amount and returns void.
Fix both: let buffer_read_binary accept a size_t instead of uint32_t
for the number of bytes to read and as a convenience return the number
of bytes actually read.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
All previous users of buffer_read_string have already been converted
to use the more intuitive buffer_read_binary, so remove the old API to
avoid some confusion.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Currently buffer_copy_bytes does not report to its caller whether
it encountered an early end of file.
Add a return value representing the number of bytes read (but not
the number of bytes copied). This way all three unusual conditions
can be distinguished: input error with buffer_ferror, output error
with ferror(outfile), early end of input by checking the return
value.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Currently there is no way to detect when input ended if it ended
early during buffer_skip_bytes. Tell the calling program how many
bytes were actually skipped for easier debugging.
Existing callers will still ignore early EOF.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Move from uint32_t to off_t as the fundamental unit of length used by
the line_buffer library. Performance would get worse if anything but
I think it's worth it for support of deltas that need to skip large
pieces (> 4 GiB).
Exception: buffer_read_string still takes a uint32_t, since it keeps
its result in an in-core obj_pool.
Callers still have to be updated to take advantage of this.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
The line_buffer library silently flags input errors until
buffer_deinit time; unfortunately, by that point usually errno is
invalid. Expose the error flag so callers can check for and
report errors early for easy debugging.
some_error_prone_operation(...);
if (buffer_ferror(buf))
return error("input error: %s", strerror(errno));
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
It can sometimes be useful to write information temporarily to file,
to read back later. These functions allow a program to use the
line_buffer facilities when doing so.
It works like this:
1. find a unique filename with buffer_tmpfile_init.
2. rewind with buffer_tmpfile_rewind. This returns a stdio
handle for writing.
3. when finished writing, declare so with
buffer_tmpfile_prepare_to_read. The return value indicates
how many bytes were written.
4. read whatever portion of the file is needed.
5. if finished, remove the temporary file with buffer_deinit.
otherwise, go back to step 2,
The svn support would use this to buffer the postimage from delta
application until the length is known and fast-import can receive
the resulting blob.
Based-on-patch-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
buffer_read_char can be used in place of buffer_read_string(1) to
avoid consuming valuable static buffer space. The delta applier will
use this to read variable-length integers one byte at a time.
Underneath, it is fgetc, wrapped so the line_buffer library can
maintain its role as gatekeeper of input.
Later it might be worth checking if fgetc_unlocked is faster ---
most line_buffer functions are not thread-safe anyway.
Helpd-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
buffer_read_string works well for non line-oriented input except for
one problem: it does not tell the caller how many bytes were actually
written. This means that unless one is very careful about checking
for errors (and eof) the calling program cannot tell the difference
between the string "foo" followed by an early end of file and the
string "foo\0bar\0baz".
So introduce a variant that reports the length, too, a thinner wrapper
around strbuf_fread. Its result is written to a strbuf so the caller
does not need to keep track of the number of bytes read.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Collect the line_buffer state in a newly public line_buffer struct.
Callers can use multiple line_buffers to manage input from multiple
files at a time.
svn-fe's delta applier will use this to stream a delta from svnrdump
and the preimage it applies to from fast-import at the same time.
The tests don't take advantage of the new features, but I think that's
okay. It is easier to find lingering examples of nonreentrant code by
searching for "static" in line_buffer.c.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Prepare for the line_buffer lib to support input from multiple files,
by collecting global state in a struct that can be easily passed
around.
No API change yet.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
This library provides thread-unsafe fgets()- and fread()-like
functions where the caller does not have to supply a buffer. It
maintains a couple of static buffers and provides an API to use
them.
[rr: allow input from files other than stdin]
[jn: with tests, documentation, and error handling improvements]
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
