1 files changed, 61 insertions, 0 deletions
diff --git a/portable/setenv.c b/portable/setenv.c
new file mode 100644
index 0000000..d66ddcd
--- /dev/null
+++ b/portable/setenv.c
@@ -0,0 +1,61 @@
+/*
+ * Replacement for a missing setenv.
+ *
+ * Provides the same functionality as the standard library routine setenv for
+ * those platforms that don't have it.
+ *
+ * Written by Russ Allbery <rra@stanford.edu>
+ * This work is hereby placed in the public domain by its author.
+ */
+
+#include <config.h>
+#include <portable/system.h>
+
+/*
+ * If we're running the test suite, rename setenv to avoid conflicts with
+ * the system version.
+ */
+#if TESTING
+# define setenv test_setenv
+int test_setenv(const char *, const char *, int);
+#endif
+
+int
+setenv(const char *name, const char *value, int overwrite)
+{
+    char *envstring;
+    size_t size;
+
+    if (!overwrite && getenv(name) != NULL)
+        return 0;
+
+    /*
+     * Allocate memory for the environment string.  We intentionally don't use
+     * concat here, or the xmalloc family of allocation routines, since the
+     * intention is to provide a replacement for the standard library function
+     * which sets errno and returns in the event of a memory allocation
+     * failure.
+     */
+    size = strlen(name) + 1 + strlen(value) + 1;
+    envstring = malloc(size);
+    if (envstring == NULL)
+        return -1;
+
+    /*
+     * Build the environment string and add it to the environment using
+     * putenv.  Systems without putenv lose, but XPG4 requires it.
+     */
+    strlcpy(envstring, name, size);
+    strlcat(envstring, "=", size);
+    strlcat(envstring, value, size);
+    return putenv(envstring);
+
+    /*
+     * Note that the memory allocated is not freed.  This is intentional; many
+     * implementations of putenv assume that the string passed to putenv will
+     * never be freed and don't make a copy of it.  Repeated use of this
+     * function will therefore leak memory, since most implementations of
+     * putenv also don't free strings removed from the environment (due to
+     * being overwritten).
+     */
+}