src/utils_subst.[ch]: Implement `subst_string'.

Works like `subst', but instead of specifying start and end offsets you
specify `needle', the string that is to be replaced. If `needle' is found
in `string' (using strstr(3)), the offset is calculated and `subst' is
called with the determined parameters.

diff --git a/src/utils_subst.c b/src/utils_subst.c
index 05dc844..3c9fe5a 100644 (file)
--- a/src/utils_subst.c
+++ b/src/utils_subst.c
@@ -78,5 +78,66 @@ char *asubst (const char *string, int off1, int off2, const char *replacement)
        return ret;
 } /* asubst */
 
+char *subst_string (char *buf, size_t buflen, const char *string,
+               const char *needle, const char *replacement)
+{
+       char *temp;
+       size_t needle_len;
+       size_t i;
+
+       if ((buf == NULL) || (string == NULL)
+                       || (needle == NULL) || (replacement == NULL))
+               return (NULL);
+
+       temp = (char *) malloc (buflen);
+       if (temp == NULL)
+       {
+               ERROR ("subst_string: malloc failed.");
+               return (NULL);
+       }
+
+       needle_len = strlen (needle);
+       strncpy (buf, string, buflen);
+
+       /* Limit the loop to prevent endless loops. */
+       for (i = 0; i < buflen; i++)
+       {
+               char *begin_ptr;
+               size_t begin;
+
+               /* Find `needle' in `buf'. */
+               begin_ptr = strstr (buf, needle);
+               if (begin_ptr == NULL)
+                       break;
+
+               /* Calculate the start offset. */
+               begin = begin_ptr - buf;
+
+               /* Substitute the region using `subst'. The result is stored in
+                * `temp'. */
+               begin_ptr = subst (temp, buflen, buf,
+                               begin, begin + needle_len,
+                               replacement);
+               if (begin_ptr == NULL)
+               {
+                       WARNING ("subst_string: subst failed.");
+                       break;
+               }
+
+               /* Copy the new string in `temp' to `buf' for the next round. */
+               strncpy (buf, temp, buflen);
+       }
+
+       if (i >= 100)
+       {
+               WARNING ("subst_string: Loop exited after %zu iterations: "
+                               "string = %s; needle = %s; replacement = %s;",
+                               i, string, needle, replacement);
+       }
+
+       sfree (temp);
+       return (buf);
+} /* char *subst_string */
+
 /* vim: set sw=4 ts=4 tw=78 noexpandtab : */
 

diff --git a/src/utils_subst.h b/src/utils_subst.h
index bba33af..4387b85 100644 (file)
--- a/src/utils_subst.h
+++ b/src/utils_subst.h
@@ -75,6 +75,25 @@ char *subst (char *buf, size_t buflen, const char *string, int off1, int off2,
  */
 char *asubst (const char *string, int off1, int off2, const char *replacement);
 
+/*
+ * subst_string:
+ *
+ * Works like `subst', but instead of specifying start and end offsets you
+ * specify `needle', the string that is to be replaced. If `needle' is found
+ * in `string' (using strstr(3)), the offset is calculated and `subst' is
+ * called with the determined parameters.
+ *
+ * If the substring is not found, no error will be indicated and
+ * `subst_string' works mostly like `strncpy'.
+ *
+ * If the substring appears multiple times, all appearances will be replaced.
+ * If the substring has been found `buflen' times, an endless loop is assumed
+ * and the loop is broken. A warning is printed and the function returns
+ * success.
+ */
+char *subst_string (char *buf, size_t buflen, const char *string,
+               const char *needle, const char *replacement);
+
 #endif /* UTILS_SUBST_H */
 
 /* vim: set sw=4 ts=4 tw=78 noexpandtab : */