Introduce rstrcat()

diff --git a/rpmio/rpmstring.c b/rpmio/rpmstring.c
index ae96c44..885bf4b 100644 (file)
--- a/rpmio/rpmstring.c
+++ b/rpmio/rpmstring.c
@@ -207,3 +207,35 @@ int rasprintf(char **strp, const char *fmt, ...)
     return n;
 }
 
+/*
+ * Concatenate strings with dynamically (re)allocated
+ * memory what prevents static buffer overflows by design.
+ * *dest is reallocated to the size of strings to concatenate.
+ *
+ * Note:
+ * 1) char *buf = rstrcat(NULL,"string"); is the same like rstrcat(&buf,"string");
+ * 2) rstrcat(&buf,NULL) returns buf
+ * 3) rstrcat(NULL,NULL) returns NULL
+ * 4) *dest and src can overlap
+ */
+char *rstrcat(char **dest, const char *src)
+{
+    if ( src == NULL ) {
+       return dest != NULL ? *dest : NULL;
+    }
+
+    if ( dest == NULL ) {
+       return xstrdup(src);
+    }
+
+    {
+       size_t dest_size = *dest != NULL ? strlen(*dest) : 0;
+       size_t src_size = strlen(src);
+
+       *dest = xrealloc(*dest, dest_size+src_size+1);          /* include '\0' */
+       memmove(&(*dest)[dest_size], src, src_size+1);
+    }
+
+    return *dest;
+}
+

diff --git a/rpmio/rpmstring.h b/rpmio/rpmstring.h
index 5b8af0c..d3f5953 100644 (file)
--- a/rpmio/rpmstring.h
+++ b/rpmio/rpmstring.h
@@ -109,6 +109,14 @@ int rstrncasecmp(const char *s1, const char * s2, size_t n)        ;
 int rasprintf(char **strp, const char *fmt, ...) RPM_GNUC_PRINTF(2, 3);
 
 /** \ingroup rpmstring
+ * Concatenate strings with dynamically (re)allocated memory.
+ * @param dest         pointer to destination string
+ * @param src          source string
+ * @return             realloc'd dest with src appended
+ */
+char *rstrcat(char **dest, const char *src);
+
+/** \ingroup rpmstring
  * Split string into fields separated by a character.
  * @param str          string
  * @param length       length of string