misc: add split_string.h

misc/split_string.h

@@ -0,0 +1,75 @@
+#ifndef BADVPN_SPLIT_STRING_H
+#define BADVPN_SPLIT_STRING_H
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+
+#include <misc/balloc.h>
+
+static char ** split_string (const char *str, char del)
+{
+    size_t len = strlen(str);
+    
+    // count parts
+    size_t num_parts = 0;
+    size_t i = 0;
+    while (1) {
+        size_t j = i;
+        while (j < len && str[j] != del) j++;
+        
+        num_parts++;
+        
+        if (num_parts == SIZE_MAX) { // need to allocate +1 pointer
+            goto fail0;
+        }
+        
+        if (j == len) {
+            break;
+        }
+        
+        i = j + 1;
+    }
+    
+    // allocate array for part pointers
+    char **result = BAllocArray(num_parts + 1, sizeof(*result));
+    if (!result) {
+        goto fail0;
+    }
+    
+    num_parts = 0;
+    i = 0;
+    while (1) {
+        size_t j = i;
+        while (j < len && str[j] != del) j++;
+        
+        if (!(result[num_parts] = malloc(j - i + 1))) {
+            goto fail1;
+        }
+        memcpy(result[num_parts], str + i, j - i);
+        result[num_parts][j - i] = '\0';
+        
+        num_parts++;
+        
+        if (j == len) {
+            break;
+        }
+        
+        i = j + 1;
+    }
+    
+    result[num_parts] = NULL;
+    
+    return result;
+    
+fail1:
+    while (num_parts-- > 0) {
+        free(result[num_parts]);
+    }
+    BFree(result);
+fail0:
+    return NULL;
+}
+
+#endif