1 files changed, 207 insertions, 0 deletions
diff --git a/src/common/psprintf.c b/src/common/psprintf.c
new file mode 100644
index 00000000000..87fd013f840
--- /dev/null
+++ b/src/common/psprintf.c
@@ -0,0 +1,207 @@
+/*-------------------------------------------------------------------------
+ *
+ * psprintf.c
+ *		sprintf into an allocated-on-demand buffer
+ *
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/psprintf.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "utils/memutils.h"
+
+
+static size_t pvsnprintf(char *buf, size_t len, const char *fmt, va_list args)
+__attribute__((format(PG_PRINTF_ATTRIBUTE, 3, 0)));
+
+
+/*
+ * psprintf
+ *
+ * Format text data under the control of fmt (an sprintf-style format string)
+ * and return it in an allocated-on-demand buffer.	The buffer is allocated
+ * with palloc in the backend, or malloc in frontend builds.  Caller is
+ * responsible to free the buffer when no longer needed, if appropriate.
+ *
+ * Errors are not returned to the caller, but are reported via elog(ERROR)
+ * in the backend, or printf-to-stderr-and-exit() in frontend builds.
+ * One should therefore think twice about using this in libpq.
+ */
+char *
+psprintf(const char *fmt,...)
+{
+	size_t		len = 128;		/* initial assumption about buffer size */
+
+	for (;;)
+	{
+		char	   *result;
+		va_list		args;
+
+		/*
+		 * Allocate result buffer.	Note that in frontend this maps to malloc
+		 * with exit-on-error.
+		 */
+		result = (char *) palloc(len);
+
+		/* Try to format the data. */
+		va_start(args, fmt);
+		len = pvsnprintf(result, len, fmt, args);
+		va_end(args);
+
+		if (len == 0)
+			return result;		/* success */
+
+		/* Release buffer and loop around to try again with larger len. */
+		pfree(result);
+	}
+}
+
+/*
+ * pvsnprintf
+ *
+ * Attempt to format text data under the control of fmt (an sprintf-style
+ * format string) and insert it into buf (which has length len).
+ *
+ * If successful, return zero.	If there's not enough space in buf, return
+ * an estimate of the buffer size needed to succeed (this *must* be more
+ * than "len", else psprintf might loop infinitely).
+ * Other error cases do not return.
+ *
+ * XXX This API is ugly, but there seems no alternative given the C spec's
+ * restrictions on what can portably be done with va_list arguments: you have
+ * to redo va_start before you can rescan the argument list, and we can't do
+ * that from here.
+ */
+static size_t
+pvsnprintf(char *buf, size_t len, const char *fmt, va_list args)
+{
+	int			nprinted;
+
+	Assert(len > 0);
+
+	errno = 0;
+
+	/*
+	 * Assert check here is to catch buggy vsnprintf that overruns the
+	 * specified buffer length.  Solaris 7 in 64-bit mode is an example of a
+	 * platform with such a bug.
+	 */
+#ifdef USE_ASSERT_CHECKING
+	buf[len - 1] = '\0';
+#endif
+
+	nprinted = vsnprintf(buf, len, fmt, args);
+
+	Assert(buf[len - 1] == '\0');
+
+	/*
+	 * If vsnprintf reports an error other than ENOMEM, fail.  The possible
+	 * causes of this are not user-facing errors, so elog should be enough.
+	 */
+	if (nprinted < 0 && errno != 0 && errno != ENOMEM)
+	{
+#ifndef FRONTEND
+		elog(ERROR, "vsnprintf failed: %m");
+#else
+		fprintf(stderr, "vsnprintf failed: %s\n", strerror(errno));
+		exit(EXIT_FAILURE);
+#endif
+	}
+
+	/*
+	 * Note: some versions of vsnprintf return the number of chars actually
+	 * stored, not the total space needed as C99 specifies.  And at least one
+	 * returns -1 on failure.  Be conservative about believing whether the
+	 * print worked.
+	 */
+	if (nprinted >= 0 && (size_t) nprinted < len - 1)
+	{
+		/* Success.  Note nprinted does not include trailing null. */
+		return 0;
+	}
+
+	if (nprinted >= 0 && (size_t) nprinted > len)
+	{
+		/*
+		 * This appears to be a C99-compliant vsnprintf, so believe its
+		 * estimate of the required space.	(If it's wrong, this code will
+		 * still work, but may loop multiple times.)  Note that the space
+		 * needed should be only nprinted+1 bytes, but we'd better allocate
+		 * one more than that so that the test above will succeed next time.
+		 *
+		 * In the corner case where the required space just barely overflows,
+		 * fall through so that we'll error out below (possibly after looping).
+		 */
+		if ((size_t) nprinted <= MaxAllocSize - 2)
+			return nprinted + 2;
+	}
+
+	/*
+	 * Buffer overrun, and we don't know how much space is needed.  Estimate
+	 * twice the previous buffer size.	If this would overflow, choke.	We use
+	 * a palloc-oriented overflow limit even when in frontend.
+	 */
+	if (len > MaxAllocSize / 2)
+	{
+#ifndef FRONTEND
+		ereport(ERROR,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+#else
+		fprintf(stderr, _("out of memory\n"));
+		exit(EXIT_FAILURE);
+#endif
+	}
+
+	return len * 2;
+}
+
+
+/*
+ * XXX this is going away shortly.
+ */
+#ifdef FRONTEND
+int
+pg_asprintf(char **ret, const char *fmt, ...)
+{
+	size_t		len = 128;		/* initial assumption about buffer size */
+
+	for (;;)
+	{
+		char	   *result;
+		va_list		args;
+
+		/*
+		 * Allocate result buffer.	Note that in frontend this maps to malloc
+		 * with exit-on-error.
+		 */
+		result = (char *) palloc(len);
+
+		/* Try to format the data. */
+		va_start(args, fmt);
+		len = pvsnprintf(result, len, fmt, args);
+		va_end(args);
+
+		if (len == 0)
+		{
+			*ret = result;
+			return 0;
+		}
+
+		/* Release buffer and loop around to try again with larger len. */
+		pfree(result);
+	}
+}
+#endif