[misc] Add an in-place string replacement function

src/misc.c

@@ -380,6 +380,49 @@ safe_snprintf_cat(char *dst, size_t n, const char *fmt, ...)
     return -1;
 }
 
+int
+safe_snreplace(char *s, size_t sz, const char *pattern, const char *replacement)
+{
+  char *ptr;
+  char *src;
+  char *dst;
+  size_t num;
+
+  if (!s)
+    return -1;
+
+  if (!pattern || !replacement)
+    return 0;
+
+  size_t p_len = strlen(pattern);
+  size_t r_len = strlen(replacement);
+  size_t s_len = strlen(s) + 1; // Incl terminator
+
+  ptr = s;
+  while ((ptr = strstr(ptr, pattern)))
+    {
+      // We will move the part of the string after the pattern from src to dst
+      src = ptr + p_len;
+      dst = ptr + r_len;
+
+      num = s_len - (src - s); // Number of bytes w/terminator we need to move
+      if (dst + num > s + sz)
+	return -1; // Not enough room
+
+      // Shift everything after the pattern to the right, use memmove since
+      // there might be an overlap
+      memmove(dst, src, num);
+
+      // Write replacement, no null terminater
+      memcpy(ptr, replacement, r_len);
+
+      // Advance ptr to avoid infinite looping
+      ptr = dst;
+    }
+
+  return 0;
+}
+
 
 /* Key/value functions */
 struct keyval *
@@ -387,7 +430,7 @@ keyval_alloc(void)
 {
   struct keyval *kv;
 
-  kv = (struct keyval *)malloc(sizeof(struct keyval));
+  kv = calloc(1, sizeof(struct keyval));
   if (!kv)
     {
       DPRINTF(E_LOG, L_MISC, "Out of memory for keyval alloc\n");
@@ -395,8 +438,6 @@ keyval_alloc(void)
       return NULL;
     }
 
-  memset(kv, 0, sizeof(struct keyval));
-
   return kv;
 }
 

src/misc.h

@@ -87,6 +87,8 @@ safe_asprintf(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 int
 safe_snprintf_cat(char *dst, size_t n, const char *fmt, ...) __attribute__ ((format (printf, 3, 4)));
 
+int
+safe_snreplace(char *s, size_t sz, const char *pattern, const char *replacement);
 
 /* Key/value functions */
 struct keyval *