diff options
Diffstat (limited to 'src/interfaces/libpq/pqexpbuffer.c')
| -rw-r--r-- | src/interfaces/libpq/pqexpbuffer.c | 65 |
1 files changed, 57 insertions, 8 deletions
diff --git a/src/interfaces/libpq/pqexpbuffer.c b/src/interfaces/libpq/pqexpbuffer.c index c8e80498d1f..aeb3a21a387 100644 --- a/src/interfaces/libpq/pqexpbuffer.c +++ b/src/interfaces/libpq/pqexpbuffer.c @@ -17,7 +17,7 @@ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/interfaces/libpq/pqexpbuffer.c,v 1.24 2008/01/01 19:46:00 momjian Exp $ + * $PostgreSQL: pgsql/src/interfaces/libpq/pqexpbuffer.c,v 1.25 2008/11/26 00:26:23 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -32,6 +32,32 @@ #include "win32.h" #endif + +/* All "broken" PQExpBuffers point to this string. */ +static const char oom_buffer[1] = ""; + + +/* + * markPQExpBufferBroken + * + * Put a PQExpBuffer in "broken" state if it isn't already. + */ +static void +markPQExpBufferBroken(PQExpBuffer str) +{ + if (str->data != oom_buffer) + free(str->data); + /* + * Casting away const here is a bit ugly, but it seems preferable to + * not marking oom_buffer const. We want to do that to encourage the + * compiler to put oom_buffer in read-only storage, so that anyone who + * tries to scribble on a broken PQExpBuffer will get a failure. + */ + str->data = (char *) oom_buffer; + str->len = 0; + str->maxlen = 0; +} + /* * createPQExpBuffer * @@ -61,6 +87,7 @@ initPQExpBuffer(PQExpBuffer str) str->data = (char *) malloc(INITIAL_EXPBUFFER_SIZE); if (str->data == NULL) { + str->data = (char *) oom_buffer; /* see comment above */ str->maxlen = 0; str->len = 0; } @@ -96,12 +123,10 @@ destroyPQExpBuffer(PQExpBuffer str) void termPQExpBuffer(PQExpBuffer str) { - if (str->data) - { + if (str->data != oom_buffer) free(str->data); - str->data = NULL; - } /* just for luck, make the buffer validly empty. */ + str->data = (char *) oom_buffer; /* see comment above */ str->maxlen = 0; str->len = 0; } @@ -109,15 +134,24 @@ termPQExpBuffer(PQExpBuffer str) /* * resetPQExpBuffer * Reset a PQExpBuffer to empty + * + * Note: if possible, a "broken" PQExpBuffer is returned to normal. */ void resetPQExpBuffer(PQExpBuffer str) { if (str) { - str->len = 0; - if (str->data) + if (str->data != oom_buffer) + { + str->len = 0; str->data[0] = '\0'; + } + else + { + /* try to reinitialize to valid state */ + initPQExpBuffer(str); + } } } @@ -126,7 +160,8 @@ resetPQExpBuffer(PQExpBuffer str) * Make sure there is enough space for 'needed' more bytes in the buffer * ('needed' does not include the terminating null). * - * Returns 1 if OK, 0 if failed to enlarge buffer. + * Returns 1 if OK, 0 if failed to enlarge buffer. (In the latter case + * the buffer is left in "broken" state.) */ int enlargePQExpBuffer(PQExpBuffer str, size_t needed) @@ -134,13 +169,19 @@ enlargePQExpBuffer(PQExpBuffer str, size_t needed) size_t newlen; char *newdata; + if (PQExpBufferBroken(str)) + return 0; /* already failed */ + /* * Guard against ridiculous "needed" values, which can occur if we're fed * bogus data. Without this, we can get an overflow or infinite loop in * the following. */ if (needed >= ((size_t) INT_MAX - str->len)) + { + markPQExpBufferBroken(str); return 0; + } needed += str->len + 1; /* total space required now */ @@ -173,6 +214,8 @@ enlargePQExpBuffer(PQExpBuffer str, size_t needed) str->maxlen = newlen; return 1; } + + markPQExpBufferBroken(str); return 0; } @@ -192,6 +235,9 @@ printfPQExpBuffer(PQExpBuffer str, const char *fmt,...) resetPQExpBuffer(str); + if (PQExpBufferBroken(str)) + return; /* already failed */ + for (;;) { /* @@ -240,6 +286,9 @@ appendPQExpBuffer(PQExpBuffer str, const char *fmt,...) size_t avail; int nprinted; + if (PQExpBufferBroken(str)) + return; /* already failed */ + for (;;) { /* |