diff options
Diffstat (limited to 'src/interfaces/libpq/libpq-int.h')
| -rw-r--r-- | src/interfaces/libpq/libpq-int.h | 64 |
1 files changed, 48 insertions, 16 deletions
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h index e05ea4bebff..76d21b07c9c 100644 --- a/src/interfaces/libpq/libpq-int.h +++ b/src/interfaces/libpq/libpq-int.h @@ -11,7 +11,7 @@ * * Copyright (c) 1994, Regents of the University of California * - * $Id: libpq-int.h,v 1.4 1998/10/01 01:40:25 tgl Exp $ + * $Id: libpq-int.h,v 1.5 1998/11/18 00:47:26 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -49,12 +49,29 @@ #define ERROR_MSG_LENGTH 4096 #define CMDSTATUS_LEN 40 -/* PGresult and the subsidiary types PGresAttDesc, PGresAttValue +/* + * PGresult and the subsidiary types PGresAttDesc, PGresAttValue * represent the result of a query (or more precisely, of a single SQL * command --- a query string given to PQexec can contain multiple commands). * Note we assume that a single command can return at most one tuple group, * hence there is no need for multiple descriptor sets. */ + +/* Subsidiary-storage management structure for PGresult. + * See space management routines in fe-exec.c for details. + * Note that space[k] refers to the k'th byte starting from the physical + * head of the block. + */ + typedef union pgresult_data PGresult_data; + + union pgresult_data + { + PGresult_data *next; /* link to next block, or NULL */ + char space[1]; /* dummy for accessing block as bytes */ + }; + +/* Data about a single attribute (column) of a query result */ + typedef struct pgresAttDesc { char *name; /* type name */ @@ -63,11 +80,20 @@ int atttypmod; /* type-specific modifier info */ } PGresAttDesc; -/* use char* for Attribute values, - ASCII tuples are guaranteed to be null-terminated - For binary tuples, the first four bytes of the value is the size, - and the bytes afterwards are the value. The binary value is - not guaranteed to be null-terminated. In fact, it can have embedded nulls +/* Data for a single attribute of a single tuple */ + +/* We use char* for Attribute values. + The value pointer always points to a null-terminated area; we add a + null (zero) byte after whatever the backend sends us. This is only + particularly useful for ASCII tuples ... with a binary value, the + value might have embedded nulls, so the application can't use C string + operators on it. But we add a null anyway for consistency. + Note that the value itself does not contain a length word. + + A NULL attribute is a special case in two ways: its len field is NULL_LEN + and its value field points to null_field in the owning PGresult. All the + NULL attributes in a query result point to the same place (there's no need + to store a null string separately for each one). */ #define NULL_LEN (-1) /* pg_result len for NULL value */ @@ -75,7 +101,7 @@ typedef struct pgresAttValue { int len; /* length in bytes of the value */ - char *value; /* actual value */ + char *value; /* actual value, plus terminating zero byte */ } PGresAttValue; struct pg_result @@ -91,15 +117,19 @@ * last insert query */ int binary; /* binary tuple values if binary == 1, * otherwise ASCII */ - /* NOTE: conn is kept here only for the temporary convenience of - * applications that rely on it being here. It will go away in a - * future release, because relying on it is a bad idea --- what if - * the PGresult has outlived the PGconn? About the only thing it was - * really good for was fetching the errorMessage, and we stash that - * here now anyway. - */ - PGconn *conn; /* connection we did the query on */ + PGconn *conn; /* connection we did the query on, if any */ char *errMsg; /* error message, or NULL if no error */ + + /* All NULL attributes in the query result point to this null string */ + char null_field[1]; + + /* Space management information. Note that attDescs and errMsg, + * if not null, point into allocated blocks. But tuples points + * to a separately malloc'd block, so that we can realloc it. + */ + PGresult_data *curBlock; /* most recently allocated block */ + int curOffset; /* start offset of free space in block */ + int spaceLeft; /* number of free bytes remaining in block */ }; /* PGAsyncStatusType defines the state of the query-execution state machine */ @@ -202,6 +232,8 @@ extern int pqPacketSend(PGconn *conn, const char *buf, size_t len); /* === in fe-exec.c === */ extern void pqSetResultError(PGresult *res, const char *msg); +extern void * pqResultAlloc(PGresult *res, int nBytes, int isBinary); +extern char * pqResultStrdup(PGresult *res, const char *str); extern void pqClearAsyncResult(PGconn *conn); /* === in fe-misc.c === */ |