Add environment-variable substitution to config options

[fio.git] / parse.c

diff --git a/parse.c b/parse.c
index b9466901eebeddbe7c7b2b634bf5d504a3abfff8..456e3bafb54f91c19c060bf42c1e152e21448467 100644 (file)
--- 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 @@ int parse_cmd_option(const char *opt, const char *val,
        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) {