1 files changed, 130 insertions, 0 deletions

diff --git a/strbuf.c b/strbuf.c
new file mode 100644
index 0000000..f823884
--- /dev/null
+++ b/strbuf.c
@@ -0,0 +1,130 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+
+#include "strbuf.h"
+
+static void die(const char *format, ...)
+{
+    va_list arg;
+
+    va_start(arg, format);
+    vfprintf(stderr, format, arg);
+    va_end(arg);
+
+    exit(-1);
+}
+
+void strbuf_init(strbuf_t *s)
+{
+    s->data = NULL;
+    s->size = 0;
+    s->length = 0;
+    s->increment = STRBUF_DEFAULT_INCREMENT;
+}
+
+strbuf_t *strbuf_new()
+{
+    strbuf_t *s;
+
+    s = malloc(sizeof(strbuf_t));
+    if (!s)
+        die("Out of memory");
+
+    strbuf_init(s);
+
+    return s;
+}
+
+void strbuf_set_increment(strbuf_t *s, int increment)
+{
+    if (increment <= 0)
+        die("BUG: Invalid string increment");
+
+    s->increment = increment;
+}
+
+void strbuf_free(strbuf_t *s)
+{
+    if (s->data)
+        free(s->data);
+    free(s);
+}
+
+char *strbuf_to_char(strbuf_t *s, int *len)
+{
+    char *data;
+
+    data = s->data;
+    if (len)
+        *len = s->length;
+
+    free(s);
+
+    return data;
+}
+
+/* Ensure strbuf can handle a string length bytes long (ignoring NULL
+ * optional termination). */
+void strbuf_resize(strbuf_t *s, int len)
+{
+    int newsize;
+
+    /* Esnure there is room for optional NULL termination */
+    newsize = len + 1;
+    /* Round up to the next increment */
+    newsize = ((newsize + s->increment - 1) / s->increment) * s->increment;
+    s->size = newsize;
+    s->data = realloc(s->data, s->size);
+    if (!s->data)
+        die("Out of memory");
+}
+
+void strbuf_append_mem(strbuf_t *s, const char *c, int len)
+{
+    if (len > strbuf_emptylen(s))
+        strbuf_resize(s, s->length + len);
+
+    memcpy(s->data + s->length, c, len);
+    s->length += len;
+}
+
+void strbuf_ensure_null(strbuf_t *s)
+{
+    s->data[s->length] = 0;
+}
+
+void strbuf_append_fmt(strbuf_t *s, const char *fmt, ...)
+{
+    va_list arg;
+    int fmt_len, try;
+    int empty_len;
+
+    /* If the first attempt to append fails, resize the buffer appropriately
+     * and try again */
+    for (try = 0; ; try++) {
+        va_start(arg, fmt);
+        /* Append the new formatted string */
+        /* fmt_len is the length of the string required, excluding the
+         * trailing NULL */
+        empty_len = strbuf_emptylen(s);
+        /* Add 1 since there is also space for the terminating NULL.
+         * If the string hasn't been allocated then empty_len == -1,
+         * and vsprintf() won't store anything on the first pass */
+        fmt_len = vsnprintf(s->data + s->length, empty_len + 1, fmt, arg);
+        va_end(arg);
+
+        if (fmt_len <= empty_len)
+            break;  /* SUCCESS */
+        if (try > 0)
+            die("BUG: length of formatted string changed");
+
+        strbuf_resize(s, s->length + fmt_len);
+    }
+
+    s->length += fmt_len;
+}
+
+/* vi:ai et sw=4 ts=4:
+ */