mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Rewrite ReadArrayStr() to avoid O(N^2) behavior on large strings,

Browse Source 
and hopefully improve code clarity while at it.  One intentional
semantics change: a backslashed space will not be treated as removable
trailing whitespace, as the prior coding would do.  ISTM that if it
wouldn't be considered removable leading whitespace, it shouldn't be
stripped at the end either.
This commit is contained in:
Tom Lane 2004-09-27 01:39:02 +00:00
parent 5a2c8cf4b1
commit ae8f7313ab
1 changed files with 115 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

206
src/backend/utils/adt/arrayfuncs.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.112 2004/09/16 03:15:52 neilc Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.113 2004/09/27 01:39:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -74,7 +74,8 @@
#define RETURN_NULL(type) do { *isNull = true; return (type) 0; } while (0)
static int ArrayCount(char *str, int *dim, char typdelim);
static Datum *ReadArrayStr(char *arrayStr, int nitems, int ndim, int *dim,
static Datum *ReadArrayStr(char *arrayStr, const char *origStr,
int nitems, int ndim, int *dim,
FmgrInfo *inputproc, Oid typioparam, int32 typmod,
char typdelim,
int typlen, bool typbyval, char typalign,
@ -325,7 +326,8 @@ array_in(PG_FUNCTION_ARGS)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("missing left brace")));
dataPtr = ReadArrayStr(p, nitems, ndim, dim, &my_extra->proc, typioparam,
dataPtr = ReadArrayStr(p, string,
nitems, ndim, dim, &my_extra->proc, typioparam,
typmod, typdelim, typlen, typbyval, typalign,
&nbytes);
nbytes += ARR_OVERHEAD(ndim);
@ -371,7 +373,7 @@ ArrayCount(char *str, int *dim, char typdelim)
temp[MAXDIM],
nelems[MAXDIM],
nelems_last[MAXDIM];
bool scanning_string = false;
bool in_quotes = false;
bool eoArray = false;
bool empty_array = true;
char *ptr;
@ -443,14 +445,14 @@ ArrayCount(char *str, int *dim, char typdelim)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", str)));
scanning_string = !scanning_string;
if (scanning_string)
in_quotes = !in_quotes;
if (in_quotes)
parse_state = ARRAY_QUOTED_ELEM_STARTED;
else
parse_state = ARRAY_QUOTED_ELEM_COMPLETED;
break;
case '{':
if (!scanning_string)
if (!in_quotes)
{
/*
* A left brace can occur if no nesting has
@ -476,7 +478,7 @@ ArrayCount(char *str, int *dim, char typdelim)
}
break;
case '}':
if (!scanning_string)
if (!in_quotes)
{
/*
* A right brace can occur after an element start,
@ -520,7 +522,7 @@ ArrayCount(char *str, int *dim, char typdelim)
}
break;
default:
if (!scanning_string)
if (!in_quotes)
{
if (*ptr == typdelim)
{
@ -595,16 +597,19 @@ ArrayCount(char *str, int *dim, char typdelim)
* declaration. Unspecified elements are initialized to zero for fixed length
* base types and to empty varlena structures for variable length base
* types. (This is pretty bogus; NULL would be much safer.)
*
* result :
* returns a palloc'd array of Datum representations of the array elements.
* If element type is pass-by-ref, the Datums point to palloc'd values.
* *nbytes is set to the amount of data space needed for the array,
* including alignment padding but not including array header overhead.
* CAUTION: the contents of "arrayStr" may be modified!
*
* CAUTION: the contents of "arrayStr" will be modified!
*---------------------------------------------------------------------------
*/
static Datum *
ReadArrayStr(char *arrayStr,
const char *origStr,
int nitems,
int ndim,
int *dim,
@ -620,9 +625,10 @@ ReadArrayStr(char *arrayStr,
int i,
nest_level = 0;
Datum *values;
char *ptr;
bool scanning_string = false;
char *srcptr;
bool in_quotes = false;
bool eoArray = false;
int totbytes;
int indx[MAXDIM],
prod[MAXDIM];
@ -630,87 +636,94 @@ ReadArrayStr(char *arrayStr,
values = (Datum *) palloc0(nitems * sizeof(Datum));
MemSet(indx, 0, sizeof(indx));
/* read array enclosed within {} */
ptr = arrayStr;
/*
* We have to remove " and \ characters to create a clean item value
* to pass to the datatype input routine. We overwrite each item
* value in-place within arrayStr to do this. srcptr is the current
* scan point, and dstptr is where we are copying to.
*
* We also want to suppress leading and trailing unquoted whitespace.
* We use the leadingspace flag to suppress leading space. Trailing
* space is tracked by using dstendptr to point to the last significant
* output character.
*
* The error checking in this routine is mostly pro-forma, since we
* expect that ArrayCount() already validated the string.
*/
srcptr = arrayStr;
while (!eoArray)
{
bool itemdone = false;
bool itemquoted = false;
int i = -1;
bool leadingspace = true;
char *itemstart;
char *eptr;
char *dstptr;
char *dstendptr;
/* skip leading whitespace */
while (isspace((unsigned char) *ptr))
ptr++;
itemstart = ptr;
i = -1;
itemstart = dstptr = dstendptr = srcptr;
while (!itemdone)
{
switch (*ptr)
switch (*srcptr)
{
case '\0':
/* Signal a premature end of the string */
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", arrayStr)));
errmsg("malformed array literal: \"%s\"",
origStr)));
break;
case '\\':
{
char *cptr;
/* Crunch the string on top of the backslash. */
for (cptr = ptr; *cptr != '\0'; cptr++)
*cptr = *(cptr + 1);
if (*ptr == '\0')
/* Skip backslash, copy next character as-is. */
srcptr++;
if (*srcptr == '\0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", arrayStr)));
errmsg("malformed array literal: \"%s\"",
origStr)));
*dstptr++ = *srcptr++;
/* Treat the escaped character as non-whitespace */
leadingspace = false;
dstendptr = dstptr;
break;
}
case '\"':
in_quotes = !in_quotes;
if (in_quotes)
leadingspace = false;
else
{
char *cptr;
scanning_string = !scanning_string;
if (scanning_string)
{
itemquoted = true;
/*
* Crunch the string on top of the first
* quote.
* Advance dstendptr when we exit in_quotes; this
* saves having to do it in all the other in_quotes
* cases.
*/
for (cptr = ptr; *cptr != '\0'; cptr++)
*cptr = *(cptr + 1);
/* Back up to not miss following character. */
ptr--;
dstendptr = dstptr;
}
srcptr++;
break;
}
case '{':
if (!scanning_string)
if (!in_quotes)
{
if (nest_level >= ndim)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", arrayStr)));
errmsg("malformed array literal: \"%s\"",
origStr)));
nest_level++;
indx[nest_level - 1] = 0;
/* skip leading whitespace */
while (isspace((unsigned char) *(ptr + 1)))
ptr++;
itemstart = ptr + 1;
srcptr++;
}
else
*dstptr++ = *srcptr++;
break;
case '}':
if (!scanning_string)
if (!in_quotes)
{
if (nest_level == 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", arrayStr)));
errmsg("malformed array literal: \"%s\"",
origStr)));
if (i == -1)
i = ArrayGetOffset0(ndim, indx, prod);
indx[nest_level - 1] = 0;
@ -718,56 +731,52 @@ ReadArrayStr(char *arrayStr,
if (nest_level == 0)
eoArray = itemdone = true;
else
{
/*
* tricky coding: terminate item value string
* at first '}', but don't process it till we
* see a typdelim char or end of array. This
* handles case where several '}'s appear
* successively in a multidimensional array.
*/
*ptr = '\0';
indx[nest_level - 1]++;
srcptr++;
}
}
else
*dstptr++ = *srcptr++;
break;
default:
if (*ptr == typdelim && !scanning_string)
if (in_quotes)
*dstptr++ = *srcptr++;
else if (*srcptr == typdelim)
{
if (i == -1)
i = ArrayGetOffset0(ndim, indx, prod);
itemdone = true;
indx[ndim - 1]++;
srcptr++;
}
break;
}
if (!itemdone)
ptr++;
}
*ptr++ = '\0';
if (i < 0 || i >= nitems)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"", arrayStr)));
/*
* skip trailing whitespace
*/
eptr = ptr - 1;
if (!itemquoted)
else if (isspace((unsigned char) *srcptr))
{
/* skip to last non-NULL, non-space, character */
while ((*eptr == '\0') || (isspace((unsigned char) *eptr)))
eptr--;
*(++eptr) = '\0';
/*
* If leading space, drop it immediately. Else,
* copy but don't advance dstendptr.
*/
if (leadingspace)
srcptr++;
else
*dstptr++ = *srcptr++;
}
else
{
/* skip to last quote character */
while (*eptr != '"')
eptr--;
*eptr = '\0';
*dstptr++ = *srcptr++;
leadingspace = false;
dstendptr = dstptr;
}
break;
}
}
Assert(dstptr < srcptr);
*dstendptr = '\0';
if (i < 0 || i >= nitems)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("malformed array literal: \"%s\"",
origStr)));
values[i] = FunctionCall3(inputproc,
CStringGetDatum(itemstart),
@ -780,7 +789,7 @@ ReadArrayStr(char *arrayStr,
*/
if (typlen > 0)
{
*nbytes = nitems * att_align(typlen, typalign);
totbytes = nitems * att_align(typlen, typalign);
if (!typbyval)
for (i = 0; i < nitems; i++)
if (values[i] == (Datum) 0)
@ -789,7 +798,7 @@ ReadArrayStr(char *arrayStr,
else
{
Assert(!typbyval);
*nbytes = 0;
totbytes = 0;
for (i = 0; i < nitems; i++)
{
if (values[i] != (Datum) 0)
@ -797,16 +806,16 @@ ReadArrayStr(char *arrayStr,
/* let's just make sure data is not toasted */
if (typlen == -1)
values[i] = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
*nbytes = att_addlength(*nbytes, typlen, values[i]);
*nbytes = att_align(*nbytes, typalign);
totbytes = att_addlength(totbytes, typlen, values[i]);
totbytes = att_align(totbytes, typalign);
}
else if (typlen == -1)
{
/* dummy varlena value (XXX bogus, see notes above) */
values[i] = PointerGetDatum(palloc(sizeof(int32)));
VARATT_SIZEP(DatumGetPointer(values[i])) = sizeof(int32);
*nbytes += sizeof(int32);
*nbytes = att_align(*nbytes, typalign);
totbytes += sizeof(int32);
totbytes = att_align(totbytes, typalign);
}
else
{
@ -814,11 +823,12 @@ ReadArrayStr(char *arrayStr,
Assert(typlen == -2);
values[i] = PointerGetDatum(palloc(1));
*((char *) DatumGetPointer(values[i])) = '\0';
*nbytes += 1;
*nbytes = att_align(*nbytes, typalign);
totbytes += 1;
totbytes = att_align(totbytes, typalign);
}
}
}
*nbytes = totbytes;
return values;
}