Add port support for unsetenv() in back branches. Needed for locale

environment fix.

3 files changed, 65 insertions, 2 deletions

diff --git a/src/include/c.h b/src/include/c.h
index 9c67797cd9a..f8e145ea96c 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: c.h,v 1.130.2.1 2005/07/18 15:54:30 tgl Exp $
+ * $Id: c.h,v 1.130.2.2 2006/01/05 00:51:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -669,4 +669,8 @@ extern int	vsnprintf(char *str, size_t count, const char *fmt, va_list args);
 #define memmove(d, s, c)		bcopy(s, d, c)
 #endif
 
+#ifndef HAVE_UNSETENV
+extern void unsetenv(const char *name);
+#endif
+
 #endif   /* C_H */
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index fd8488e20c0..33c960e5f59 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -8,7 +8,7 @@
  * or in pg_config.h afterwards.  Of course, if you edit pg_config.h, then your
  * changes will be overwritten the next time you run configure.
  *
- * $Id: pg_config.h.in,v 1.32.2.1 2002/11/08 05:23:09 tgl Exp $
+ * $Id: pg_config.h.in,v 1.32.2.2 2006/01/05 00:51:52 tgl Exp $
  */
 
 #ifndef PG_CONFIG_H
@@ -441,6 +441,9 @@
 /* Set to 1 if you have isinf() */
 #undef HAVE_ISINF
 
+/* Define to 1 if you have the `unsetenv' function. */
+#undef HAVE_UNSETENV
+
 /*
  *	These are all related to port/isinf.c 
  */
diff --git a/src/port/unsetenv.c b/src/port/unsetenv.c
new file mode 100644
index 00000000000..09e14f2d93b
--- /dev/null
+++ b/src/port/unsetenv.c
@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * unsetenv.c
+ *	  unsetenv() emulation for machines without it
+ *
+ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  $PostgreSQL: pgsql/src/port/unsetenv.c,v 1.6.4.1 2006/01/05 00:51:52 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+
+void
+unsetenv(const char *name)
+{
+	char	   *envstr;
+
+	if (getenv(name) == NULL)
+		return;					/* no work */
+
+	/*
+	 * The technique embodied here works if libc follows the Single Unix Spec
+	 * and actually uses the storage passed to putenv() to hold the environ
+	 * entry.  When we clobber the entry in the second step we are ensuring
+	 * that we zap the actual environ member.  However, there are some libc
+	 * implementations (notably recent BSDs) that do not obey SUS but copy the
+	 * presented string.  This method fails on such platforms.	Hopefully all
+	 * such platforms have unsetenv() and thus won't be using this hack.
+	 *
+	 * Note that repeatedly setting and unsetting a var using this code will
+	 * leak memory.
+	 */
+
+	envstr = (char *) malloc(strlen(name) + 2);
+	if (!envstr)				/* not much we can do if no memory */
+		return;
+
+	/* Override the existing setting by forcibly defining the var */
+	sprintf(envstr, "%s=", name);
+	putenv(envstr);
+
+	/* Now we can clobber the variable definition this way: */
+	strcpy(envstr, "=");
+
+	/*
+	 * This last putenv cleans up if we have multiple zero-length names as a
+	 * result of unsetting multiple things.
+	 */
+	putenv(envstr);
+}