diff options
Diffstat (limited to 'src/common/pg_lzcompress.c')
| -rw-r--r-- | src/common/pg_lzcompress.c | 42 |
1 files changed, 19 insertions, 23 deletions
diff --git a/src/common/pg_lzcompress.c b/src/common/pg_lzcompress.c index f15725a57c0..97b0e40e403 100644 --- a/src/common/pg_lzcompress.c +++ b/src/common/pg_lzcompress.c @@ -29,7 +29,7 @@ * * int32 * pglz_decompress(const char *source, int32 slen, char *dest, - * int32 rawsize) + * int32 rawsize, bool check_complete) * * source is the compressed input. * @@ -44,6 +44,12 @@ * * rawsize is the length of the uncompressed data. * + * check_complete is a flag to let us know if -1 should be + * returned in cases where we don't reach the end of the + * source or dest buffers, or not. This should be false + * if the caller is asking for only a partial result and + * true otherwise. + * * The return value is the number of bytes written in the * buffer dest, or -1 if decompression fails. * @@ -674,13 +680,14 @@ pglz_compress(const char *source, int32 slen, char *dest, * pglz_decompress - * * Decompresses source into dest. Returns the number of bytes - * decompressed in the destination buffer, or -1 if decompression - * fails. + * decompressed in the destination buffer, and *optionally* + * checks that both the source and dest buffers have been + * fully read and written to, respectively. * ---------- */ int32 pglz_decompress(const char *source, int32 slen, char *dest, - int32 rawsize) + int32 rawsize, bool check_complete) { const unsigned char *sp; const unsigned char *srcend; @@ -701,8 +708,9 @@ pglz_decompress(const char *source, int32 slen, char *dest, unsigned char ctrl = *sp++; int ctrlc; - for (ctrlc = 0; ctrlc < 8 && sp < srcend; ctrlc++) + for (ctrlc = 0; ctrlc < 8 && sp < srcend && dp < destend; ctrlc++) { + if (ctrl & 1) { /* @@ -722,24 +730,12 @@ pglz_decompress(const char *source, int32 slen, char *dest, len += *sp++; /* - * Check for output buffer overrun, to ensure we don't clobber - * memory in case of corrupt input. Note: we must advance dp - * here to ensure the error is detected below the loop. We - * don't simply put the elog inside the loop since that will - * probably interfere with optimization. - */ - if (dp + len > destend) - { - dp += len; - break; - } - - /* * Now we copy the bytes specified by the tag from OUTPUT to * OUTPUT. It is dangerous and platform dependent to use * memcpy() here, because the copied areas could overlap * extremely! */ + len = Min(len, destend - dp); while (len--) { *dp = dp[-off]; @@ -752,9 +748,6 @@ pglz_decompress(const char *source, int32 slen, char *dest, * An unset control bit means LITERAL BYTE. So we just copy * one from INPUT to OUTPUT. */ - if (dp >= destend) /* check for buffer overrun */ - break; /* do not clobber memory */ - *dp++ = *sp++; } @@ -767,12 +760,15 @@ pglz_decompress(const char *source, int32 slen, char *dest, /* * Check we decompressed the right amount. + * If we are slicing, then we won't necessarily + * be at the end of the source or dest buffers + * when we hit a stop, so we don't test them. */ - if (dp != destend || sp != srcend) + if (check_complete && (dp != destend || sp != srcend)) return -1; /* * That's it. */ - return rawsize; + return (char*)dp - dest; } |