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Commitbcf4d35

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Minor cleanup of PQunescapeBytea(). Avoid unportable assumptions about
behavior of malloc and realloc when request size is 0. Fix escapesequence recognizer so that only valid 3-digit octal sequences aretreated as escape sequences ... isdigit() is not a correct test.
1 parent774f570 commitbcf4d35

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1 file changed

+34
-21
lines changed

1 file changed

+34
-21
lines changed

‎src/interfaces/libpq/fe-exec.c

Lines changed: 34 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.152 2003/10/19 21:36:41 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.153 2003/10/31 17:43:10 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2326,21 +2326,21 @@ PQescapeBytea(const unsigned char *bintext, size_t binlen, size_t *bytealen)
23262326
returnresult;
23272327
}
23282328

2329-
#defineVAL(CH) ((CH) - '0')
2329+
#defineISFIRSTOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '3')
2330+
#defineISOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '7')
2331+
#defineOCTVAL(CH) ((CH) - '0')
23302332

23312333
/*
23322334
*PQunescapeBytea - converts the null terminated string representation
23332335
*of a bytea, strtext, into binary, filling a buffer. It returns a
2334-
*pointer to the bufferwhich isNULL on error, and the size of the
2336+
*pointer to the buffer(orNULL on error), and the size of the
23352337
*buffer in retbuflen. The pointer may subsequently be used as an
23362338
*argument to the function free(3). It is the reverse of PQescapeBytea.
23372339
*
23382340
*The following transformations are made:
2339-
*\' == ASCII 39 == '
23402341
*\\ == ASCII 92 == \
23412342
*\ooo == a byte whose value = ooo (ooo is an octal number)
23422343
*\x == x (x is any character not matched by the above transformations)
2343-
*
23442344
*/
23452345
unsignedchar*
23462346
PQunescapeBytea(constunsignedchar*strtext,size_t*retbuflen)
@@ -2349,21 +2349,22 @@ PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
23492349
buflen;
23502350
unsignedchar*buffer,
23512351
*tmpbuf;
2352-
inti,
2353-
j,
2354-
byte;
2352+
size_ti,
2353+
j;
23552354

23562355
if (strtext==NULL)
23572356
returnNULL;
23582357

2359-
strtextlen=strlen(strtext);/* will shrink, also we discover
2360-
* if strtext isn't NULL
2361-
* terminated */
2362-
buffer= (unsignedchar*)malloc(strtextlen);
2358+
strtextlen=strlen(strtext);
2359+
/*
2360+
* Length of input is max length of output, but add one to avoid
2361+
* unportable malloc(0) if input is zero-length.
2362+
*/
2363+
buffer= (unsignedchar*)malloc(strtextlen+1);
23632364
if (buffer==NULL)
23642365
returnNULL;
23652366

2366-
for (i=j=buflen=0;i<(int)strtextlen;)
2367+
for (i=j=0;i<strtextlen;)
23672368
{
23682369
switch (strtext[i])
23692370
{
@@ -2373,26 +2374,38 @@ PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
23732374
buffer[j++]=strtext[i++];
23742375
else
23752376
{
2376-
if ((isdigit(strtext[i]))&&
2377-
(isdigit(strtext[i+1]))&&
2378-
(isdigit(strtext[i+2])))
2377+
if ((ISFIRSTOCTDIGIT(strtext[i]))&&
2378+
(ISOCTDIGIT(strtext[i+1]))&&
2379+
(ISOCTDIGIT(strtext[i+2])))
23792380
{
2380-
byte=VAL(strtext[i++]);
2381-
byte= (byte <<3)+VAL(strtext[i++]);
2382-
buffer[j++]= (byte <<3)+VAL(strtext[i++]);
2381+
intbyte;
2382+
2383+
byte=OCTVAL(strtext[i++]);
2384+
byte= (byte <<3)+OCTVAL(strtext[i++]);
2385+
byte= (byte <<3)+OCTVAL(strtext[i++]);
2386+
buffer[j++]=byte;
23832387
}
23842388
}
2389+
/*
2390+
* Note: if we see '\' followed by something that isn't
2391+
* a recognized escape sequence, we loop around having
2392+
* done nothing except advance i. Therefore the something
2393+
* will be emitted as ordinary data on the next cycle.
2394+
* Corner case: '\' at end of string will just be discarded.
2395+
*/
23852396
break;
23862397

23872398
default:
23882399
buffer[j++]=strtext[i++];
2400+
break;
23892401
}
23902402
}
2391-
buflen=j;/* buflen is the length of theunquoted
2403+
buflen=j;/* buflen is the length of thedequoted
23922404
* data */
23932405

23942406
/* Shrink the buffer to be no larger than necessary */
2395-
tmpbuf=realloc(buffer,buflen);
2407+
/* +1 avoids unportable behavior when buflen==0 */
2408+
tmpbuf=realloc(buffer,buflen+1);
23962409

23972410
/* It would only be a very brain-dead realloc that could fail, but... */
23982411
if (!tmpbuf)

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