Add environment-variable substitution to config options
Strings of the form ${VARNAME} in config option strings are substituted with
the value of the environment variable VARNAME. Only the right hand side of
an option assignment undergoes substitution. If VARNAME is empty or
undefined, the empty string is substituted.
Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.c b/parse.c
index b946690..456e3ba 100644
--- a/parse.c
+++ b/parse.c
@@ -8,6 +8,7 @@
#include <string.h>
#include <errno.h>
#include <limits.h>
+#include <stdlib.h>
#include "parse.h"
#include "debug.h"
@@ -529,12 +530,61 @@
return 1;
}
+/*
+ * Return a copy of the input string with substrings of the form ${VARNAME}
+ * substituted with the value of the environment variable VARNAME. The
+ * substitution always occurs, even if VARNAME is empty or the corresponding
+ * environment variable undefined.
+ */
+static char *option_dup_subs(const char *opt)
+{
+ char out[OPT_LEN_MAX+1];
+ char in[OPT_LEN_MAX+1];
+ char *outptr = out;
+ char *inptr = in;
+ char *ch1, *ch2, *env;
+ ssize_t nchr = OPT_LEN_MAX;
+ size_t envlen;
+
+ in[OPT_LEN_MAX] = '\0';
+ strncpy(in, opt, OPT_LEN_MAX);
+
+ while (*inptr && nchr > 0) {
+ if (inptr[0] == '$' && inptr[1] == '{') {
+ ch2 = strchr(inptr, '}');
+ if (ch2 && inptr+1 < ch2) {
+ ch1 = inptr+2;
+ inptr = ch2+1;
+ *ch2 = '\0';
+
+ env = getenv(ch1);
+ if (env) {
+ envlen = strlen(env);
+ if (envlen <= nchr) {
+ memcpy(outptr, env, envlen);
+ outptr += envlen;
+ nchr -= envlen;
+ }
+ }
+
+ continue;
+ }
+ }
+
+ *outptr++ = *inptr++;
+ --nchr;
+ }
+
+ *outptr = '\0';
+ return strdup(out);
+}
+
int parse_option(const char *opt, struct fio_option *options, void *data)
{
struct fio_option *o;
char *post, *tmp;
- tmp = strdup(opt);
+ tmp = option_dup_subs(opt);
o = get_option(tmp, options, &post);
if (!o) {