[misc] New utility functions: trim, atrim and safe_snprintf_cat

src/db.c

@@ -6767,31 +6767,24 @@ db_statements_prepare(void)
   char *query;
   char keystr[2048];
   char valstr[1024];
-  int keyremain;
-  int valremain;
   int ret;
   int i;
 
   // Prepare "INSERT INTO files" statement
-  keyremain = sizeof(keystr);
-  valremain = sizeof(valstr);
+  memset(keystr, 0, sizeof(keystr));
+  memset(valstr, 0, sizeof(valstr));
   for (i = 0; i < ARRAY_SIZE(mfi_cols_map); i++)
     {
       if (mfi_cols_map[i].flag == DB_FLAG_AUTO)
 	continue;
 
-      keyremain -= snprintf(keystr + sizeof(keystr) - keyremain, keyremain, "%s, ", mfi_cols_map[i].name);
-      valremain -= snprintf(valstr + sizeof(valstr) - valremain, valremain, "?, ");
-      if (keyremain <= 0 || valremain <= 0)
-	{
-	  DPRINTF(E_FATAL, L_DB, "Bug! Size of keystr or valstr is insufficient (%d, %d)\n", keyremain, valremain);
-	  return -1;
-	}
+      CHECK_ERR(L_DB, safe_snprintf_cat(keystr, sizeof(keystr), "%s, ", mfi_cols_map[i].name));
+      CHECK_ERR(L_DB, safe_snprintf_cat(valstr, sizeof(valstr), "?, "));
     }
 
-  // Terminates at the ending ", "
-  keystr[sizeof(keystr) - keyremain - 2] = '\0';
-  valstr[sizeof(valstr) - valremain - 2] = '\0';
+  // Terminate at the ending ", "
+  *(strrchr(keystr, ',')) = '\0';
+  *(strrchr(valstr, ',')) = '\0';
 
   CHECK_NULL(L_DB, query = db_mprintf("INSERT INTO files (%s) VALUES (%s);", keystr, valstr));
 
@@ -6806,22 +6799,17 @@ db_statements_prepare(void)
   free(query);
 
   // Prepare "UPDATE files" statement
-  keyremain = sizeof(keystr);
+  memset(keystr, 0, sizeof(keystr));
   for (i = 0; i < ARRAY_SIZE(mfi_cols_map); i++)
     {
       if (mfi_cols_map[i].flag == DB_FLAG_AUTO)
 	continue;
 
-      keyremain -= snprintf(keystr + sizeof(keystr) - keyremain, keyremain, "%s = ?, ", mfi_cols_map[i].name);
-      if (keyremain <= 0)
-	{
-	  DPRINTF(E_FATAL, L_DB, "Bug! Size of keystr is insufficient (%d)\n", keyremain);
-	  return -1;
-	}
+      CHECK_ERR(L_DB, safe_snprintf_cat(keystr, sizeof(keystr), "%s = ?, ", mfi_cols_map[i].name));
     }
 
-  // Terminates at the ending ", "
-  keystr[sizeof(keystr) - keyremain - 2] = '\0';
+  // Terminate at the ending ", "
+  *(strrchr(keystr, ',')) = '\0';
 
   CHECK_NULL(L_DB, query = db_mprintf("UPDATE files SET %s WHERE %s = ?;", keystr, mfi_cols_map[0].name));
 

src/lastfm.c

@@ -154,7 +154,7 @@ response_process(struct http_client_ctx *ctx, char **errmsg)
       DPRINTF(E_DBG, L_LASTFM, "LastFM response:\n%s\n", body);
 
       if (errmsg)
-	*errmsg = trimwhitespace(mxmlGetOpaque(e_node));
+	*errmsg = atrim(mxmlGetOpaque(e_node));
 
       mxmlDelete(tree);
       return -1;
@@ -180,7 +180,7 @@ response_process(struct http_client_ctx *ctx, char **errmsg)
       return -1;
     }
 
-  sk = trimwhitespace(mxmlGetOpaque(s_node));
+  sk = atrim(mxmlGetOpaque(s_node));
   if (sk)
     {
       DPRINTF(E_LOG, L_LASTFM, "Got session key from LastFM: %s\n", sk);

src/misc.c

@@ -33,6 +33,7 @@
 #include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <limits.h>
 #include <sys/param.h>
 #ifndef CLOCK_REALTIME
@@ -341,6 +342,7 @@ safe_asprintf(const char *fmt, ...)
 {
   char *ret = NULL;
   va_list va;
+
   va_start(va, fmt);
   if (vasprintf(&ret, fmt, va) < 0)
     {
@@ -348,9 +350,34 @@ safe_asprintf(const char *fmt, ...)
       abort();
     }
   va_end(va);
+
   return ret;
 }
 
+int
+safe_snprintf_cat(char *dst, size_t n, const char *fmt, ...)
+{
+  size_t dstlen;
+  va_list va;
+  int ret;
+
+  if (!dst || !fmt)
+    return -1;
+
+  dstlen = strlen(dst);
+  if (n < dstlen)
+    return -1;
+
+  va_start(va, fmt);
+  ret = vsnprintf(dst + dstlen, n - dstlen, fmt, va);
+  va_end(va);
+
+  if (ret >= 0 && ret < n - dstlen)
+    return 0;
+  else
+    return -1;
+}
+
 
 /* Key/value functions */
 struct keyval *
@@ -586,7 +613,7 @@ m_readfile(const char *path, int num_lines)
 	  goto error;
 	}
 
-      lines[i] = trimwhitespace(line);
+      lines[i] = atrim(line);
       if (!lines[i] || (strlen(lines[i]) == 0))
 	{
 	  DPRINTF(E_LOG, L_MISC, "Line %d in '%s' is invalid\n", i+1, path);
@@ -643,40 +670,58 @@ unicode_fixup_string(char *str, const char *fromcode)
 }
 
 char *
-trimwhitespace(const char *str)
+trim(char *str)
 {
-  char *ptr;
-  char *start;
-  char *out;
+  size_t start; // Position of first non-space char
+  size_t term;  // Position of 0-terminator
 
   if (!str)
     return NULL;
 
-  // Find the beginning
-  while (isspace(*str))
-    str++;
+  start = 0;
+  term  = strlen(str);
 
-  if (*str == 0) // All spaces?
-    return strdup("");
+  while ((start < term) && isspace(str[start]))
+    start++;
+  while ((term > start) && isspace(str[term - 1]))
+    term--;
 
-  // Make copy, because we will need to insert a null terminator
-  start = strdup(str);
-  if (!start)
+  str[term] = '\0';
+
+  // Shift chars incl. terminator
+  if (start)
+    memmove(str, str + start, term - start + 1);
+
+  return str;
+}
+
+char *
+atrim(const char *str)
+{
+  size_t start; // Position of first non-space char
+  size_t term;  // Position of 0-terminator
+  size_t size;
+  char *result;
+
+  if (!str)
     return NULL;
 
-  // Find the end
-  ptr = start + strlen(start) - 1;
-  while (ptr > start && isspace(*ptr))
-    ptr--;
+  start = 0;
+  term  = strlen(str);
 
-  // Insert null terminator
-  *(ptr+1) = 0;
+  while ((start < term) && isspace(str[start]))
+    start++;
+  while ((term > start) && isspace(str[term - 1]))
+    term--;
 
-  out = strdup(start);
+  size = term - start + 1;
 
-  free(start);
+  result = malloc(size);
 
-  return out;
+  memcpy(result, str + start, size);
+  result[size - 1] = '\0';
+
+  return result;
 }
 
 void

src/misc.h

@@ -58,6 +58,10 @@ safe_strdup(const char *str);
 char *
 safe_asprintf(const char *fmt, ...);
 
+int
+safe_snprintf_cat(char *dst, size_t n, const char *fmt, ...);
+
+
 /* Key/value functions */
 struct keyval *
 keyval_alloc(void);
@@ -87,8 +91,13 @@ m_readfile(const char *path, int num_lines);
 char *
 unicode_fixup_string(char *str, const char *fromcode);
 
+// Modifies str so it is trimmed. Returns pointer to str.
 char *
-trimwhitespace(const char *str);
+trim(char *str);
+
+// Copies the trimmed part of str to a newly allocated string (caller must free)
+char *
+atrim(const char *str);
 
 void
 swap_pointers(char **a, char **b);
@@ -105,8 +114,7 @@ b64_encode(const uint8_t *in, size_t len);
 uint64_t
 murmur_hash64(const void *key, int len, uint32_t seed);
 
-
-/* Checks if the address is in a network that is configured as trusted */
+// Checks if the address is in a network that is configured as trusted
 bool
 peer_address_is_trusted(const char *addr);