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4981fe750b
The packet_read function reads from a descriptor. The packet_get_line function is similar, but reads from an in-memory buffer, and uses a completely separate implementation. This patch teaches the generic packet_read function to accept either source, and we can do away with packet_get_line's implementation. There are two other differences to account for between the old and new functions. The first is that we used to read into a strbuf, but now read into a fixed size buffer. The only two callers are fine with that, and in fact it simplifies their code, since they can use the same static-buffer interface as the rest of the packet_read_line callers (and we provide a similar convenience wrapper for reading from a buffer rather than a descriptor). This is technically an externally-visible behavior change in that we used to accept arbitrary sized packets up to 65532 bytes, and now cap out at LARGE_PACKET_MAX, 65520. In practice this doesn't matter, as we use it only for parsing smart-http headers (of which there is exactly one defined, and it is small and fixed-size). And any extension headers would be breaking the protocol to go over LARGE_PACKET_MAX anyway. The other difference is that packet_get_line would return on error rather than dying. However, both callers of packet_get_line are actually improved by dying. The first caller does its own error checking, but we can drop that; as a result, we'll actually get more specific reporting about protocol breakage when packet_read dies internally. The only downside is that packet_read will not print the smart-http URL that failed, but that's not a big deal; anybody not debugging can already see the remote's URL already, and anybody debugging would want to run with GIT_CURL_VERBOSE anyway to see way more information. The second caller, which is just trying to skip past any extra smart-http headers (of which there are none defined, but which we allow to keep room for future expansion), did not error check at all. As a result, it would treat an error just like a flush packet. The resulting mess would generally cause an error later in get_remote_heads, but now we get error reporting much closer to the source of the problem. Brown-paper-bag-fixes-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
83 lines
3.0 KiB
C
83 lines
3.0 KiB
C
#ifndef PKTLINE_H
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#define PKTLINE_H
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#include "git-compat-util.h"
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#include "strbuf.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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void packet_flush(int fd);
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void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
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void packet_buf_flush(struct strbuf *buf);
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void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
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/*
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* Read a packetized line into the buffer, which must be at least size bytes
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* long. The return value specifies the number of bytes read into the buffer.
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*
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* If src_buffer is not NULL (and nor is *src_buffer), it should point to a
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* buffer containing the packet data to parse, of at least *src_len bytes.
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* After the function returns, src_buf will be incremented and src_len
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* decremented by the number of bytes consumed.
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*
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* If src_buffer (or *src_buffer) is NULL, then data is read from the
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* descriptor "fd".
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*
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* If options does not contain PACKET_READ_GENTLE_ON_EOF, we will die under any
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* of the following conditions:
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*
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* 1. Read error from descriptor.
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*
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* 2. Protocol error from the remote (e.g., bogus length characters).
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*
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* 3. Receiving a packet larger than "size" bytes.
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*
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* 4. Truncated output from the remote (e.g., we expected a packet but got
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* EOF, or we got a partial packet followed by EOF).
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*
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* If options does contain PACKET_READ_GENTLE_ON_EOF, we will not die on
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* condition 4 (truncated input), but instead return -1. However, we will still
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* die for the other 3 conditions.
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*
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* If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
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* present) is removed from the buffer before returning.
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*/
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#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
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#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
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int packet_read(int fd, char **src_buffer, size_t *src_len, char
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*buffer, unsigned size, int options);
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/*
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* Convenience wrapper for packet_read that is not gentle, and sets the
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* CHOMP_NEWLINE option. The return value is NULL for a flush packet,
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* and otherwise points to a static buffer (that may be overwritten by
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* subsequent calls). If the size parameter is not NULL, the length of the
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* packet is written to it.
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*/
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char *packet_read_line(int fd, int *size);
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/*
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* Same as packet_read_line, but read from a buf rather than a descriptor;
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* see packet_read for details on how src_* is used.
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*/
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char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
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#define DEFAULT_PACKET_MAX 1000
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#define LARGE_PACKET_MAX 65520
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extern char packet_buffer[LARGE_PACKET_MAX];
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#endif
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