MINOR: tools: add an unsetenv() implementation
Older Solaris and AIX versions do not have unsetenv(). This adds a
fairly simple implementation which scans the environment, for use
with those systems. It will simply require to pass the define in
the "DEFINE" macro at build time like this :
DEFINE="-Dunsetenv=my_unsetenv"
diff --git a/src/standard.c b/src/standard.c
index 09bc155..1035e20 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -3699,6 +3699,38 @@
return ret;
}
+/* removes environment variable <name> from the environment as found in
+ * environ. This is only provided as an alternative for systems without
+ * unsetenv() (old Solaris and AIX versions). THIS IS NOT THREAD SAFE.
+ * The principle is to scan environ for each occurence of variable name
+ * <name> and to replace the matching pointers with the last pointer of
+ * the array (since variables are not ordered).
+ * It always returns 0 (success).
+ */
+int my_unsetenv(const char *name)
+{
+ extern char **environ;
+ char **p = environ;
+ int vars;
+ int next;
+ int len;
+
+ len = strlen(name);
+ for (vars = 0; p[vars]; vars++)
+ ;
+ next = 0;
+ while (next < vars) {
+ if (strncmp(p[next], name, len) != 0 || p[next][len] != '=') {
+ next++;
+ continue;
+ }
+ if (next < vars - 1)
+ p[next] = p[vars - 1];
+ p[--vars] = NULL;
+ }
+ return 0;
+}
+
/* Convert occurrences of environment variables in the input string to their
* corresponding value. A variable is identified as a series of alphanumeric
* characters or underscores following a '$' sign. The <in> string must be