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| -rw-r--r-- | src/backend/libpq/pqformat.c | 643 |
1 files changed, 643 insertions, 0 deletions
diff --git a/src/backend/libpq/pqformat.c b/src/backend/libpq/pqformat.c new file mode 100644 index 0000000..9c24df3 --- /dev/null +++ b/src/backend/libpq/pqformat.c @@ -0,0 +1,643 @@ +/*------------------------------------------------------------------------- + * + * pqformat.c + * Routines for formatting and parsing frontend/backend messages + * + * Outgoing messages are built up in a StringInfo buffer (which is expansible) + * and then sent in a single call to pq_putmessage. This module provides data + * formatting/conversion routines that are needed to produce valid messages. + * Note in particular the distinction between "raw data" and "text"; raw data + * is message protocol characters and binary values that are not subject to + * character set conversion, while text is converted by character encoding + * rules. + * + * Incoming messages are similarly read into a StringInfo buffer, via + * pq_getmessage, and then parsed and converted from that using the routines + * in this module. + * + * These same routines support reading and writing of external binary formats + * (typsend/typreceive routines). The conversion routines for individual + * data types are exactly the same, only initialization and completion + * are different. + * + * + * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/backend/libpq/pqformat.c + * + *------------------------------------------------------------------------- + */ +/* + * INTERFACE ROUTINES + * Message assembly and output: + * pq_beginmessage - initialize StringInfo buffer + * pq_sendbyte - append a raw byte to a StringInfo buffer + * pq_sendint - append a binary integer to a StringInfo buffer + * pq_sendint64 - append a binary 8-byte int to a StringInfo buffer + * pq_sendfloat4 - append a float4 to a StringInfo buffer + * pq_sendfloat8 - append a float8 to a StringInfo buffer + * pq_sendbytes - append raw data to a StringInfo buffer + * pq_sendcountedtext - append a counted text string (with character set conversion) + * pq_sendtext - append a text string (with conversion) + * pq_sendstring - append a null-terminated text string (with conversion) + * pq_send_ascii_string - append a null-terminated text string (without conversion) + * pq_endmessage - send the completed message to the frontend + * Note: it is also possible to append data to the StringInfo buffer using + * the regular StringInfo routines, but this is discouraged since required + * character set conversion may not occur. + * + * typsend support (construct a bytea value containing external binary data): + * pq_begintypsend - initialize StringInfo buffer + * pq_endtypsend - return the completed string as a "bytea*" + * + * Special-case message output: + * pq_puttextmessage - generate a character set-converted message in one step + * pq_putemptymessage - convenience routine for message with empty body + * + * Message parsing after input: + * pq_getmsgbyte - get a raw byte from a message buffer + * pq_getmsgint - get a binary integer from a message buffer + * pq_getmsgint64 - get a binary 8-byte int from a message buffer + * pq_getmsgfloat4 - get a float4 from a message buffer + * pq_getmsgfloat8 - get a float8 from a message buffer + * pq_getmsgbytes - get raw data from a message buffer + * pq_copymsgbytes - copy raw data from a message buffer + * pq_getmsgtext - get a counted text string (with conversion) + * pq_getmsgstring - get a null-terminated text string (with conversion) + * pq_getmsgrawstring - get a null-terminated text string - NO conversion + * pq_getmsgend - verify message fully consumed + */ + +#include "postgres.h" + +#include <sys/param.h> + +#include "libpq/libpq.h" +#include "libpq/pqformat.h" +#include "mb/pg_wchar.h" +#include "port/pg_bswap.h" + + +/* -------------------------------- + * pq_beginmessage - initialize for sending a message + * -------------------------------- + */ +void +pq_beginmessage(StringInfo buf, char msgtype) +{ + initStringInfo(buf); + + /* + * We stash the message type into the buffer's cursor field, expecting + * that the pq_sendXXX routines won't touch it. We could alternatively + * make it the first byte of the buffer contents, but this seems easier. + */ + buf->cursor = msgtype; +} + +/* -------------------------------- + + * pq_beginmessage_reuse - initialize for sending a message, reuse buffer + * + * This requires the buffer to be allocated in a sufficiently long-lived + * memory context. + * -------------------------------- + */ +void +pq_beginmessage_reuse(StringInfo buf, char msgtype) +{ + resetStringInfo(buf); + + /* + * We stash the message type into the buffer's cursor field, expecting + * that the pq_sendXXX routines won't touch it. We could alternatively + * make it the first byte of the buffer contents, but this seems easier. + */ + buf->cursor = msgtype; +} + +/* -------------------------------- + * pq_sendbytes - append raw data to a StringInfo buffer + * -------------------------------- + */ +void +pq_sendbytes(StringInfo buf, const char *data, int datalen) +{ + /* use variant that maintains a trailing null-byte, out of caution */ + appendBinaryStringInfo(buf, data, datalen); +} + +/* -------------------------------- + * pq_sendcountedtext - append a counted text string (with character set conversion) + * + * The data sent to the frontend by this routine is a 4-byte count field + * followed by the string. The count includes itself or not, as per the + * countincludesself flag (pre-3.0 protocol requires it to include itself). + * The passed text string need not be null-terminated, and the data sent + * to the frontend isn't either. + * -------------------------------- + */ +void +pq_sendcountedtext(StringInfo buf, const char *str, int slen, + bool countincludesself) +{ + int extra = countincludesself ? 4 : 0; + char *p; + + p = pg_server_to_client(str, slen); + if (p != str) /* actual conversion has been done? */ + { + slen = strlen(p); + pq_sendint32(buf, slen + extra); + appendBinaryStringInfoNT(buf, p, slen); + pfree(p); + } + else + { + pq_sendint32(buf, slen + extra); + appendBinaryStringInfoNT(buf, str, slen); + } +} + +/* -------------------------------- + * pq_sendtext - append a text string (with conversion) + * + * The passed text string need not be null-terminated, and the data sent + * to the frontend isn't either. Note that this is not actually useful + * for direct frontend transmissions, since there'd be no way for the + * frontend to determine the string length. But it is useful for binary + * format conversions. + * -------------------------------- + */ +void +pq_sendtext(StringInfo buf, const char *str, int slen) +{ + char *p; + + p = pg_server_to_client(str, slen); + if (p != str) /* actual conversion has been done? */ + { + slen = strlen(p); + appendBinaryStringInfo(buf, p, slen); + pfree(p); + } + else + appendBinaryStringInfo(buf, str, slen); +} + +/* -------------------------------- + * pq_sendstring - append a null-terminated text string (with conversion) + * + * NB: passed text string must be null-terminated, and so is the data + * sent to the frontend. + * -------------------------------- + */ +void +pq_sendstring(StringInfo buf, const char *str) +{ + int slen = strlen(str); + char *p; + + p = pg_server_to_client(str, slen); + if (p != str) /* actual conversion has been done? */ + { + slen = strlen(p); + appendBinaryStringInfoNT(buf, p, slen + 1); + pfree(p); + } + else + appendBinaryStringInfoNT(buf, str, slen + 1); +} + +/* -------------------------------- + * pq_send_ascii_string - append a null-terminated text string (without conversion) + * + * This function intentionally bypasses encoding conversion, instead just + * silently replacing any non-7-bit-ASCII characters with question marks. + * It is used only when we are having trouble sending an error message to + * the client with normal localization and encoding conversion. The caller + * should already have taken measures to ensure the string is just ASCII; + * the extra work here is just to make certain we don't send a badly encoded + * string to the client (which might or might not be robust about that). + * + * NB: passed text string must be null-terminated, and so is the data + * sent to the frontend. + * -------------------------------- + */ +void +pq_send_ascii_string(StringInfo buf, const char *str) +{ + while (*str) + { + char ch = *str++; + + if (IS_HIGHBIT_SET(ch)) + ch = '?'; + appendStringInfoCharMacro(buf, ch); + } + appendStringInfoChar(buf, '\0'); +} + +/* -------------------------------- + * pq_sendfloat4 - append a float4 to a StringInfo buffer + * + * The point of this routine is to localize knowledge of the external binary + * representation of float4, which is a component of several datatypes. + * + * We currently assume that float4 should be byte-swapped in the same way + * as int4. This rule is not perfect but it gives us portability across + * most IEEE-float-using architectures. + * -------------------------------- + */ +void +pq_sendfloat4(StringInfo buf, float4 f) +{ + union + { + float4 f; + uint32 i; + } swap; + + swap.f = f; + pq_sendint32(buf, swap.i); +} + +/* -------------------------------- + * pq_sendfloat8 - append a float8 to a StringInfo buffer + * + * The point of this routine is to localize knowledge of the external binary + * representation of float8, which is a component of several datatypes. + * + * We currently assume that float8 should be byte-swapped in the same way + * as int8. This rule is not perfect but it gives us portability across + * most IEEE-float-using architectures. + * -------------------------------- + */ +void +pq_sendfloat8(StringInfo buf, float8 f) +{ + union + { + float8 f; + int64 i; + } swap; + + swap.f = f; + pq_sendint64(buf, swap.i); +} + +/* -------------------------------- + * pq_endmessage - send the completed message to the frontend + * + * The data buffer is pfree()d, but if the StringInfo was allocated with + * makeStringInfo then the caller must still pfree it. + * -------------------------------- + */ +void +pq_endmessage(StringInfo buf) +{ + /* msgtype was saved in cursor field */ + (void) pq_putmessage(buf->cursor, buf->data, buf->len); + /* no need to complain about any failure, since pqcomm.c already did */ + pfree(buf->data); + buf->data = NULL; +} + +/* -------------------------------- + * pq_endmessage_reuse - send the completed message to the frontend + * + * The data buffer is *not* freed, allowing to reuse the buffer with + * pq_beginmessage_reuse. + -------------------------------- + */ + +void +pq_endmessage_reuse(StringInfo buf) +{ + /* msgtype was saved in cursor field */ + (void) pq_putmessage(buf->cursor, buf->data, buf->len); +} + + +/* -------------------------------- + * pq_begintypsend - initialize for constructing a bytea result + * -------------------------------- + */ +void +pq_begintypsend(StringInfo buf) +{ + initStringInfo(buf); + /* Reserve four bytes for the bytea length word */ + appendStringInfoCharMacro(buf, '\0'); + appendStringInfoCharMacro(buf, '\0'); + appendStringInfoCharMacro(buf, '\0'); + appendStringInfoCharMacro(buf, '\0'); +} + +/* -------------------------------- + * pq_endtypsend - finish constructing a bytea result + * + * The data buffer is returned as the palloc'd bytea value. (We expect + * that it will be suitably aligned for this because it has been palloc'd.) + * We assume the StringInfoData is just a local variable in the caller and + * need not be pfree'd. + * -------------------------------- + */ +bytea * +pq_endtypsend(StringInfo buf) +{ + bytea *result = (bytea *) buf->data; + + /* Insert correct length into bytea length word */ + Assert(buf->len >= VARHDRSZ); + SET_VARSIZE(result, buf->len); + + return result; +} + + +/* -------------------------------- + * pq_puttextmessage - generate a character set-converted message in one step + * + * This is the same as the pqcomm.c routine pq_putmessage, except that + * the message body is a null-terminated string to which encoding + * conversion applies. + * -------------------------------- + */ +void +pq_puttextmessage(char msgtype, const char *str) +{ + int slen = strlen(str); + char *p; + + p = pg_server_to_client(str, slen); + if (p != str) /* actual conversion has been done? */ + { + (void) pq_putmessage(msgtype, p, strlen(p) + 1); + pfree(p); + return; + } + (void) pq_putmessage(msgtype, str, slen + 1); +} + + +/* -------------------------------- + * pq_putemptymessage - convenience routine for message with empty body + * -------------------------------- + */ +void +pq_putemptymessage(char msgtype) +{ + (void) pq_putmessage(msgtype, NULL, 0); +} + + +/* -------------------------------- + * pq_getmsgbyte - get a raw byte from a message buffer + * -------------------------------- + */ +int +pq_getmsgbyte(StringInfo msg) +{ + if (msg->cursor >= msg->len) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("no data left in message"))); + return (unsigned char) msg->data[msg->cursor++]; +} + +/* -------------------------------- + * pq_getmsgint - get a binary integer from a message buffer + * + * Values are treated as unsigned. + * -------------------------------- + */ +unsigned int +pq_getmsgint(StringInfo msg, int b) +{ + unsigned int result; + unsigned char n8; + uint16 n16; + uint32 n32; + + switch (b) + { + case 1: + pq_copymsgbytes(msg, (char *) &n8, 1); + result = n8; + break; + case 2: + pq_copymsgbytes(msg, (char *) &n16, 2); + result = pg_ntoh16(n16); + break; + case 4: + pq_copymsgbytes(msg, (char *) &n32, 4); + result = pg_ntoh32(n32); + break; + default: + elog(ERROR, "unsupported integer size %d", b); + result = 0; /* keep compiler quiet */ + break; + } + return result; +} + +/* -------------------------------- + * pq_getmsgint64 - get a binary 8-byte int from a message buffer + * + * It is tempting to merge this with pq_getmsgint, but we'd have to make the + * result int64 for all data widths --- that could be a big performance + * hit on machines where int64 isn't efficient. + * -------------------------------- + */ +int64 +pq_getmsgint64(StringInfo msg) +{ + uint64 n64; + + pq_copymsgbytes(msg, (char *) &n64, sizeof(n64)); + + return pg_ntoh64(n64); +} + +/* -------------------------------- + * pq_getmsgfloat4 - get a float4 from a message buffer + * + * See notes for pq_sendfloat4. + * -------------------------------- + */ +float4 +pq_getmsgfloat4(StringInfo msg) +{ + union + { + float4 f; + uint32 i; + } swap; + + swap.i = pq_getmsgint(msg, 4); + return swap.f; +} + +/* -------------------------------- + * pq_getmsgfloat8 - get a float8 from a message buffer + * + * See notes for pq_sendfloat8. + * -------------------------------- + */ +float8 +pq_getmsgfloat8(StringInfo msg) +{ + union + { + float8 f; + int64 i; + } swap; + + swap.i = pq_getmsgint64(msg); + return swap.f; +} + +/* -------------------------------- + * pq_getmsgbytes - get raw data from a message buffer + * + * Returns a pointer directly into the message buffer; note this + * may not have any particular alignment. + * -------------------------------- + */ +const char * +pq_getmsgbytes(StringInfo msg, int datalen) +{ + const char *result; + + if (datalen < 0 || datalen > (msg->len - msg->cursor)) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("insufficient data left in message"))); + result = &msg->data[msg->cursor]; + msg->cursor += datalen; + return result; +} + +/* -------------------------------- + * pq_copymsgbytes - copy raw data from a message buffer + * + * Same as above, except data is copied to caller's buffer. + * -------------------------------- + */ +void +pq_copymsgbytes(StringInfo msg, char *buf, int datalen) +{ + if (datalen < 0 || datalen > (msg->len - msg->cursor)) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("insufficient data left in message"))); + memcpy(buf, &msg->data[msg->cursor], datalen); + msg->cursor += datalen; +} + +/* -------------------------------- + * pq_getmsgtext - get a counted text string (with conversion) + * + * Always returns a pointer to a freshly palloc'd result. + * The result has a trailing null, *and* we return its strlen in *nbytes. + * -------------------------------- + */ +char * +pq_getmsgtext(StringInfo msg, int rawbytes, int *nbytes) +{ + char *str; + char *p; + + if (rawbytes < 0 || rawbytes > (msg->len - msg->cursor)) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("insufficient data left in message"))); + str = &msg->data[msg->cursor]; + msg->cursor += rawbytes; + + p = pg_client_to_server(str, rawbytes); + if (p != str) /* actual conversion has been done? */ + *nbytes = strlen(p); + else + { + p = (char *) palloc(rawbytes + 1); + memcpy(p, str, rawbytes); + p[rawbytes] = '\0'; + *nbytes = rawbytes; + } + return p; +} + +/* -------------------------------- + * pq_getmsgstring - get a null-terminated text string (with conversion) + * + * May return a pointer directly into the message buffer, or a pointer + * to a palloc'd conversion result. + * -------------------------------- + */ +const char * +pq_getmsgstring(StringInfo msg) +{ + char *str; + int slen; + + str = &msg->data[msg->cursor]; + + /* + * It's safe to use strlen() here because a StringInfo is guaranteed to + * have a trailing null byte. But check we found a null inside the + * message. + */ + slen = strlen(str); + if (msg->cursor + slen >= msg->len) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid string in message"))); + msg->cursor += slen + 1; + + return pg_client_to_server(str, slen); +} + +/* -------------------------------- + * pq_getmsgrawstring - get a null-terminated text string - NO conversion + * + * Returns a pointer directly into the message buffer. + * -------------------------------- + */ +const char * +pq_getmsgrawstring(StringInfo msg) +{ + char *str; + int slen; + + str = &msg->data[msg->cursor]; + + /* + * It's safe to use strlen() here because a StringInfo is guaranteed to + * have a trailing null byte. But check we found a null inside the + * message. + */ + slen = strlen(str); + if (msg->cursor + slen >= msg->len) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid string in message"))); + msg->cursor += slen + 1; + + return str; +} + +/* -------------------------------- + * pq_getmsgend - verify message fully consumed + * -------------------------------- + */ +void +pq_getmsgend(StringInfo msg) +{ + if (msg->cursor != msg->len) + ereport(ERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid message format"))); +} |